Survey on Drosophila suzukii and Ceratitis capitata (Diptera: Drosophilidae, Tephritidae) and Associated Eucoilinae Species (Hymenoptera: Figitidae) in Northwestern Argentina. First Record of Dicerataspis grenadensis and Leptopilina boulardi as Parasitoids of D. suzukii

The Southeast Asian-native Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), also known as "spotted-wing Drosophila," is one of the most globally invasive agricultural species. Although D. suzukii is a pest spread throughout all the Argentinian fruit-growing regions, few information has been published on its impact on local fruit production. Parasitoid species associated with D. suzukii in Argentina belong to Pteromalidae (Chalcidoidea), Diapriidae (Diaprioidea), both attacking host pupae, and Figitidae (Cynipoidea), which attack host larvae. Nine Eucoilinae (Figitidae) species, belonging to Dicerataspis, Dieucoila, Euxestophaga, Ganaspis, Hexacola, and Leptopilina genera, have been associated with D. suzukii in Argentina. Ceratitis capitata (Wiedemann), commonly known as "medfly," is native to Africa and has a worldwide distribution, covering many tropical, subtropical, and temperate regions. In Argentina, C. capitata has been associated with several native hymenopterous parasitoids belonging to Braconidae (Ichneumonioidea), Eulophidae (Chalcidoidea), Pteromalidae, Diapriidae, and Figitidae families. Only two eucoline species, Ganaspis pelleranoi (Brèthes) and Leptopilina haywardi (Blanchard) have been related to medfly in Argentina. We report new trophic associations between the parasitoids Dicerataspis grenadensis Ashmead and Leptopilina boulardi (Barbotin, Carton and Kelner-Pillault) and D. suzukii, and between the parasitoid Odontosema albinerve Kieffer and C. capitata, after surveys conducted in Tucumán, northwestern Argentina. An annotated checklist and a taxonomic key of Eucoilinae associated with both invasive pests, in Argentina, are also provided.

Imperfect match between radiation exposure times required for conidial viability loss and infective capacity reduction attenuate UV-B impact on Beauveria bassiana

BACKGROUND

UV-B radiation represents a significant challenge for the widespread use of entomopathogenic fungi in pest management. This study focused on research of the asynchronous response between virulence and conidial viability against Ceratitis capitata adults using specific statistical models. Moreover, it was also investigated whether the observed differences in susceptibility to UV-B radiation in in vitro assays among three selected isolates of Beauveria bassiana were reflected in the above-mentioned asynchrony.

RESULTS

While the irradiation of the three isolates of B. bassiana was associated with a significant loss of conidial viability, their virulence was not significantly affected compared to nonirradiated treatments when exposed to 1200 mW m-2 for 6 h before or after the inoculation of C. capitata. In fact, the irradiation time needed to reduce the mortality to 50% compared to the controls was 34.69 h for EABb 10/225-Fil, 16.36 h for EABb 09/20-Fil, and 24.59 h for EABb 09/28-Fil. Meanwhile, the irradiation time necessary to reduce conidial viability to 50% was 9.89 h for EABb 10/225-Fil, 8.74 h for EABb 09/20-Fil, and 4.71 h for EABb 09/28-Fil.

CONCLUSION

These results highlight the importance of modeling the response of entomopathogenic fungi virulence and conidial susceptibility when exposed to UV-B radiation for the selection of environmentally competent isolates, regardless of the results obtained in previous in vitro assays on conidial germination. This strategic approach is critical in overcoming the challenges posed by UV-B radiation and holds the key to realizing the full potential of entomopathogenic fungi in pest management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Deep orange gene editing triggers temperature-sensitive lethal phenotypes in Ceratitis capitata

BACKGROUND

The Mediterranean fruit fly, Ceratitis capitata, is a significant agricultural pest managed through area-wide integrated pest management (AW-IPM) including a sterile insect technique (SIT) component. Male-only releases increase the efficiency and cost-effectiveness of SIT programs, which can be achieved through the development of genetic sexing strains (GSS). The most successful GSS developed to date is the C. capitata VIENNA 8 GSS, constructed using classical genetic approaches and an irradiation-induced translocation with two selectable markers: the white pupae (wp) and temperature-sensitive lethal (tsl) genes. However, currently used methods for selecting suitable markers and inducing translocations are stochastic and non-specific, resulting in a laborious and time-consuming process. Recent efforts have focused on identifying the gene(s) and the causal mutation(s) for suitable phenotypes, such as wp and tsl, which could be used as selectable markers for developing a generic approach for constructing GSS. The wp gene was recently identified, and efforts have been initiated to identify the tsl gene. This study investigates Ceratitis capitata deep orange (Ccdor) as a tsl candidate gene and its potential to induce tsl phenotypes.

RESULTS

An integrated approach based on cytogenetics, genomics, bioinformatics, and gene editing was used to characterize the Ccdor. Its location was confirmed on the right arm of chromosome 5 in the putative tsl genomic region. Knock-out of Ccdor using CRISPR/Cas9-NHEJ and targeting the fourth exon resulted in lethality at mid- and late-pupal stage, while the successful application of CRISPR HDR introducing a point mutation on the sixth exon resulted in the establishment of the desired strain and two additional strains (dor 12del and dor 51dup), all of them expressing tsl phenotypes and presenting no (or minimal) fitness cost when reared at 25 °C. One of the strains exhibited complete lethality when embryos were exposed at 36 °C.

CONCLUSIONS

Gene editing of the deep orange gene in Ceratitis capitata resulted in the establishment of temperature-sensitive lethal mutant strains. The induced mutations did not significantly affect the rearing efficiency of the strains. As deep orange is a highly conserved gene, these data suggest that it can be considered a target for the development of tsl mutations which could potentially be used to develop novel genetic sexing strains in insect pests and disease vectors.

Shadow Effect for Small Insect Detection by W-Band Pulsed Radar

In radar entomology, one primary challenge is detecting small species (smaller than 5 cm) since these tiny insects reflect radiation that can be poorly observable and, therefore, difficult to interpret. After a literature search on radar entomology, this research found few works where it has been possible to sense insects with dimensions smaller than 5 cm using radars. This paper describes different methodologies to detect Mediterranean fruit flies with 5-6 mm sizes using a pulsed W-band radar and presents the experimental results that validate the procedures. The article's main contribution is the successful detection of Mediterranean fruit flies employing the shadow effect on the backscattered radar signal, achieving an 11% difference in received power when flies are present. So far, according to the information available and the literature search, this work is the first to detect small insects less than 1 cm long using a pulsed radar in W-Band. The results show that the proposed shadow effect is a viable alternative to the current sensors used in smart traps, as it allows not only detection but also counting the number of insects in the trap.

Profiles of Volatiles Emitted from Orange Fruits Infested by Ceratitis capitata (Diptera: Tephritidae)

The profiles of volatile organic compounds (VOCs) emitted from orange fruits infested by Ceratitis capitata were examined. VOCs were collected from the headspace of oranges immediately, 24 h, 5 days, 8 days, and 13 days after oviposition and when larvae exit the fruit by applying either static or dynamic sampling techniques. A total of 32 and 47 compounds were detected in infested orange fruits when using static and dynamic techniques, respectively. Differences in the volatile profile of oranges were observed. Classification models were employed, showing that infested fruits emitted a chemical profile distinct from that of non-infested ones. Limonene was associated with cell disruption. (E)-β-Ocimene, (E)-4,8-dimethyl-1,3,7-nonatriene, hexyl butanoate, butyl hexanoate, and hexyl hexanoate were the VOCs that were correlated with the infestation of sweet oranges by C. capitata.

Identification of volatile compounds from fruits aroma and citrus essential oils and their effect on oviposition of Ceratitis capitata (Diptera: Tephritidae)

Ceratitis capitata (Wiedemann), also known as the Mediterranean fruit fly, is one of the most serious pests for several fresh fruit commodities causing extensive fruit losses worldwide. The response of C. capitata adults to fruit and nonfruit volatiles has been extensively studied. However, the linkage between fruit volatiles and the female ovipositional choice has not been fully elucidated. The present study focused on identifying the volatile organic compounds emitted by detached intact fresh fruits (oranges, lemons, bergamots, and apples) and citrus essential oils and evaluate their effect on Mediterranean fruit fly oviposition. There were more than 130 and 45 volatiles compounds detected in fruits odors and citrus essential oils, respectively. The volatile profile of fruits was dominated either from terpenes and terpenoids or from esters of butanoic, hexanoic, and octanoic acids while limonene was by far the most abundant compound in all citrus essential oils. Oviposition of C. capitata was strongly affected by volatiles emanated from both intact fruit and the citrus essential oils. Regarding the volatiles of the intact fruits, the odor of sweet orange elicited strong oviposition responses to females, while bergamot had the least stimulatory effect on oviposition. Bergamot oil also elicited the least oviposition stimulation compared to sweet orange and lemon essential oils. Our discussion elaborates on the role of fruit volatiles on host finding behavior and fruit susceptibility to C. capitata infestation and includes possible practical implication of the above findings.

How aggressive interactions with biomimetic agents optimize reproductive performances in mass-reared males of the Mediterranean fruit fly

Mass-rearing procedures of insect species, often used in biological control and Sterile Insect Technique, can reduce the insects competitiveness in foraging, dispersal, and mating. The evocation of certain behaviours responsible to induce specific neuroendocrine products may restore or improve the competitiveness of mass-reared individuals. Herein, we used a mass-reared strain of Ceratitis capitata as model organism. C. capitata is a polyphagous pest exhibiting territorial displays that are closely related to its reproductive performance. We tested if the behaviour of C. capitata males could be altered by hybrid aggressive interactions with a conspecific-mimicking robotic fly, leading to more competitive individuals in subsequent mating events. Aggressive interactions with the robotic fly had a notable effect on subsequent courtship and mating sequences of males that performed longer courtship displays compared to naïve individuals. Furthermore, previous interactions with the robotic fly produced a higher mating success of males. Reproductive performances of C. capitata males may be improved by specific octopaminergic neurones activated during previous aggressive interactions with the robotic fly. This study adds fundamental knowledge on the potential role of specific neuro-behavioural processes in the ecology of tephritid species and paves the way to innovative biotechnological control methods based on robotics and bionics.

Insecticidal Properties of Erythritol on Four Tropical Tephritid Fruit Flies, Zeugodacus cucurbitae, Ceratitis capitata, Bactrocera dorsalis, and B. latifrons (Diptera: Tephritidae)

Tephritid fruit flies are among the most destructive agricultural pests of fruits and vegetables worldwide and can impose trade barriers against the movement of fresh tropical commodities. Primary pre-harvest control methods for these flies rely on the spraying of conventional chemical insecticides or bait sprays. However, resistance to these control methods has been reported in fruit flies. Erythritol is a non-nutritive sugar alternative for human consumption, which has been tested and confirmed for its insecticidal properties against various insect pest species. In this study, using laboratory bioassays, we evaluated the insecticidal effect of erythritol alone or various erythritol formulations containing sucrose and/or protein on four tropical fruit fly species established in Hawaii (e.g., melon fly, Mediterranean fruit fly, oriental fruit fly, and Malaysian fruit fly). In addition, the effects of other non-nutritive hexose and pentose sugar alcohols, such as sorbitol, mannitol, and xylitol, were tested. Among the different standalone and combinatory treatments tested, 1M erythritol and a combinatory formulation of 2M erythritol + 0.5M sucrose appeared to be the most detrimental to the survival of all four species of tested flies, suggesting the potential of using erythritol as a non-toxic management tool for the control of tropical tephritid fruit flies.

Augmentative Releases of Two Diachasmimorpha longicaudata (Hymenoptera: Braconidae) Population Lines Under Field-Cage Conditions to Control Ceratitis capitata (Diptera: Tephritidae)

Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), known as Medfly, is a severe agricultural invasive pest in Argentinian fruit-producing regions. The native habitat disturbance and introduction and spread of exotic host plants strongly favored Medfly proliferation. This scenario is common throughout the northern subtropical citrus-growing region. Environmentally friendly strategies to suppress Medfly populations by the National Fruit Fly Control and Eradication Program have currently been taken. One of these actions involves augmentative biological control through releases of the exotic parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). Consequently, the hypothesis that the effectiveness of D. longicaudata females, from two different population lines, in controlling Medfly larvae progressively increases as the density of released females increases was tested. One parasitoid line derives from larvae of a biparental Medfly strain. The other hails from irradiated larvae of the genetic sexing Temperature Sensitive Lethal Vienna-8 medfly strain reared at the "BioPlanta San Juan" biofactory. Parasitoids foraged for 24 h on peaches artificially inoculated with naked lab-reared biparental Medfly larvae. Peaches were placed near the roof or on the ground in field cages. Five treatments (20, 40, 80, 160, and 320 females released) and a control (no parasitoids) for each population line were carried out throughout summer and autumn 2016. Host density (200 larvae) remained constant. At 320 released parasitoid females, both D. longicaudata population lines highly increased the Medfly mortality in both testing seasons, and foraged skillfully on peaches at both fruit height levels. These data encourage the application of augmentative biological control against Medfly.

Genomic and cytogenetic analysis of the Ceratitis capitata temperature-sensitive lethal region

Genetic sexing strains (GSS) are an important tool in support of sterile insect technique (SIT) applications against insect pests and disease vectors. The yet unknown temperature-sensitive lethal (tsl) gene and the recently identified white pupae (wp) gene have been used as selectable markers in the most successful GSS developed so far, the Ceratitis capitata (medfly) VIENNA 8 GSS. The molecular identification of the tsl gene may open the way for its use as a marker for the development of GSS in other insect pests and disease vectors of SIT importance. Prior studies have already shown that the tsl gene is located on the right arm of chromosome 5, between the wp and Zw loci (tsl genomic region). In the present study, we used genomic, transcriptomic, bioinformatic, and cytogenetic approaches to characterize and analyze this genomic region in wild-type and tsl mutant medfly strains. Our results suggested the presence of 561 genes, with 322 of them carrying SNPs and/or insertion-deletion (indel) mutations in the tsl genomic region. Furthermore, comparative transcriptomic analysis indicated the presence of 32 differentially expressed genes, and bioinformatic analysis revealed the presence of 33 orthologs with a described heat-sensitive phenotype of Drosophila melanogaster in this region. These data can be used in functional genetic studies to identify the tsl gene(s) and the causal mutation(s) responsible for the temperature-sensitive lethal phenotype in medfly, and potentially additional genes causing a similar phenotype.

Intelligent detection of citrus fruit pests using machine vision system and convolutional neural network through transfer learning technique

Plant pests and diseases play a significant role in reducing the quality of agricultural products. As one of the most important plant pathogens, pests like Mediterranean fruit fly cause significant damage to crops and thus annually farmers face a lot of loss in their products. Therefore, the use of modern and non-destructive methods such as machine vision systems and deep learning for early detection of pests in agricultural products is of particular importance. In this study, citrus fruit images were taken in three stages: 1) before pest infestation, 2) beginning of fruit infestation, and 3) eight days after the second stage, in natural light conditions (7000-11,000 lux). A total of 1519 images were prepared for all classes. To classify the images, 70% of the images were used for the network training stage, 10% and 20% of the images were used for the validation and testing stages. Four pre-trained CNN models, namely ResNet-50, GoogleNet, VGG-16 and AlexNet as well as the SGDm, RMSProp and Adam optimization algorithms were used to identify and classify healthy fruit and fruit infected with the Mediterranean fly. The results of evaluating the models in the pest outbreak stage showed that the VGG-16 model with the help of SGDm algorithm had the best efficiency with the highest detection accuracy and F1 of 98.33% and 98.36%, respectively. The evaluation of the third stage showed that the AlexNet model with the help of SGDm algorithm had the best result with the highest detection accuracy and F1 of 99.33% and 99.34%, respectively. AlexNet model using SGDm optimization algorithm had the shortest network training time (323 s). The results of this study showed that convolutional neural network method and machine vision system can be effective in controlling and managing pests in orchards and other agricultural products.

A Deep-Learning-Based Detection Approach for the Identification of Insect Species of Economic Importance

Artificial Intelligence (AI) and automation are fostering more sustainable and effective solutions for a wide spectrum of agricultural problems. Pest management is a major challenge for crop production that can benefit from machine learning techniques to detect and monitor specific pests and diseases. Traditional monitoring is labor intensive, time demanding, and expensive, while machine learning paradigms may support cost-effective crop protection decisions. However, previous studies mainly relied on morphological images of stationary or immobilized animals. Other features related to living animals behaving in the environment (e.g., walking trajectories, different postures, etc.) have been overlooked so far. In this study, we developed a detection method based on convolutional neural network (CNN) that can accurately classify in real-time two tephritid species (Ceratitis capitata and Bactrocera oleae) free to move and change their posture. Results showed a successful automatic detection (i.e., precision rate about 93%) in real-time of C. capitata and B. oleae adults using a camera sensor at a fixed height. In addition, the similar shape and movement patterns of the two insects did not interfere with the network precision. The proposed method can be extended to other pest species, needing minimal data pre-processing and similar architecture.

Temperature Sensitivity of Wild-Type, Mutant and Genetic Sexing Strains of Ceratitis capitata

Area-wide integrated pest management (AW-IPM) programmes with a sterile insect technique component (SIT) are used to control populations of insect pests worldwide, including the Mediterranean fruit fly, Ceratitis capitata. SIT consists of the mass rearing, radiation-induced sterilization, handling, and release of sterile insects over the target area. Although SIT can be performed by using both sterile males and females, male-only releases significantly increase the efficiency and cost-effectiveness of SIT applications. Male-only releases can be achieved by using genetic sexing strains (GSS). The medfly VIENNA 8 GSS is based on two selectable markers, the white pupae (wp) gene, and the temperature-sensitive lethal (tsl) genes. The latter allows the elimination of females by exposing embryos to elevated temperatures. This study assessed the temperature sensitivity of twenty-seven medfly strains through a TSLT. Our results indicated significant differences among the strains regarding egg hatching as well as pupal and adult recovery rates due to the presence or absence of the tsl mutation and/or the genetic background of the strains. Our findings are discussed in the context of SIT applications, the importance of the tsl gene for developing genetic sexing strains, and climate change.

Evaluation of Trap Devices for Mass Trapping of Ceratitis capitata (Diptera: Tephritidae) Populations

The Mediterranean fruit fly (medfly), Ceratitis capitata, is a key pest of fruit crops in a wide range of climatic zone. Its economic importance is increasing due to its invasion and establishment in new geographical areas caused by global warming. Generally, the management of medfly infestation has been carried out with the use of synthetic pyrethroids and phosphorganic insecticides. Other containment approaches include attract-and-kill, biological control, and the sterile insect technique. The mass trapping technique can be considered an eco-friendly method to use in combination with other control systems. The present study reported the trapping effectiveness of commercially available devices (Decis Trap, Tephri Trap Ecological, and Conetrap) baited with different types of female attractants (Econex Trypack and Biodelear) under different thermal conditions. The performance of trapping systems was evaluated in semi-field cages. Our results showed that the combination of Conetrap with Biodelear was not proven effective, while the Tephri Trap baited with Trypack or Biodelear and the Decis Trap reported the same performance in capturing females and could be used for medfly mass trapping.

Chemical Composition of Essential Oils from Leaves and Fruits of Juniperus foetidissima and Their Attractancy and Toxicity to Two Economically Important Tephritid Fruit Fly Species, Ceratitis capitata and Anastrepha suspensa

The present study analyzed the chemical composition of Juniperus foetidissima Willd. essential oils (EOs) and evaluated their attractancy and toxicity to two agriculturally important tephritid fruit flies. The composition of hydrodistilled EOs obtained from leaves (JFLEO) and fruits (JFFEO) of J. foetidissima was analyzed by GC-FID and GC-MS. The main compounds were α-pinene (45%) and cedrol (18%) in the JFLEO and α-pinene (42%), α-thujone (12%), and β-thujone (25%) in the JFFEO. In behavioral bioassays of the male Mediterranean fruit fly, Ceratitis capitata (Wiedemann), both JFLEO and JFFEO showed strong attraction comparable to that observed with two positive controls, Melaleuca alternifolia and Tetradenia riparia EOs. In topical bioassays of the female Caribbean fruit fly, Anastrepha suspensa (Loew), the toxicity of JFFEO was two-fold higher than that of JFLEO, with the LD₅₀ values being 10.46 and 22.07 µg/µL, respectively. This could be due to differences in chemical components between JFLEO and JFFEO. The JFFEO was dominated by 48% monoterpene hydrocarbons (MH) and 46% oxygenated monoterpenes (OM), while JFLEO consisted of 57% MH, 18% OM, and 20% oxygenated sesquiterpenes (OS). This is the first study to evaluate the attractancy and toxicity of J. foetidissima EOs to tephritid fruit flies. Our results indicate that JFFEO has the potential for application to the management of pest tephritid species, and further investigation is warranted.

Pupation Substrate Type and Volume Affect Pupation, Quality Parameters and Production Costs of a Reproductive Colony of Ceratitis capitata (Diptera: Tephritidae) VIENNA 8 Genetic Sexing Strain

Simple Summary

The Mediterranean fruit fly, Ceratitis capitata, is a pest of fruit and vegetables in many parts of the world. The Sterile Insect Technique (SIT) is used as an environmentally friendly method for the control and/or eradication of this pest. A critical step in the production of sterile insects in biofactories is when the larvae complete their development and begin metamorphosis to become pupae. Artificial substrates are used to facilitate pupation, but little research has been devoted to this critical moment in the life cycle of the insect. We tested seven pupation substrates and five substrate volumes for a reproductive colony of C. capitata VIENNA 8 genetic sexing strain for SIT application in Mexico. One type of cellulose and sawdust at relatively low ratios of substrate:larvae enhanced pupation and were more cost-effective to produce one million pupae than other substrates including fine wheat bran currently used in a SIT mass-rearing facility in Mexico. Our study contributes to improving rearing processes involved in SIT-based pest control.

Abstract

Adequate pupation substrates and substrate volume are critical factors in the mass-rearing of insects for Sterile Insect Technique (SIT) applications. To identify an ideal pupation substrate for a reproductive colony of Ceratitis capitata (Wiedemann) VIENNA 8 genetic sexing strain, we first examined pupation in cellulose from recycled paper (cellulose I), sawdust, fine wheat bran, vermiculite and coconut fiber using a volume of 2.5–12.5 mL of substrate for each 5 mL volume of fly larvae. We found a positive relationship between substrate volume and pupation, with cellulose I generating the highest proportions of pupation and coconut fiber the lowest. Higher proportions of female flies (white pupae) pupated in sawdust. The proportion of female fliers increased as substrate volume rose in sawdust and coconut fiber, whereas it decreased in vermiculite and cellulose. In a second experiment, we tested three types of cellulose differing in physicochemical characteristics (celluloses I, II and III), sawdust, and fine wheat bran using a substrate:larvae ratio of 1:1. The three types of cellulose produced the highest pupation levels. The highest proportions of female fliers were observed in sawdust, and cellulose types III and II. Cellulose III and sawdust at relatively low volumes were more cost-effective to produce one million pupae than other substrates, including fine wheat bran used in a mass-rearing facility in Mexico.

Effectiveness of Entomopathogenic Nematodes Against Ceratitis capitata (Diptera: Tephritidae) Pupae and Nematode Compatibility with Chemical Insecticides

The Mediterranean fruit fly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae) is among the main pests of fruit crops worldwide. Biological control using entomopathogenic nematodes (EPNs) may be an alternative to suppress populations of this pest. Thus, the aim of this study was to evaluate the pathogenicity and virulence of six EPN isolates (Heterorhabditis bacteriophora HB, H. amazonensis IBCB-n24, Steinernema carpocapsae IBCB-n02, S. rarum PAM-25, S. glaseri IBCB-n47, and S. brazilense IBCB-n06) against C. capitata pupae. The compatibility of EPNs with different chemical insecticides that are registered for management of C. capitata was also assessed. Isolates of H. bacteriophora HB and S. brazilense IBCB-n06 at a concentration of 1,000 infective juveniles (IJ)/ml proved to be most pathogenic to C. capitata (70 and 80% mortality, respectively). In contrast, the isolates H. amazonensis IBCB-n24, Steinernema carpocapsae IBCB-n02, S. rarum PAM-25, S. glaseri IBCB-n47 provided pupal mortality of less than 60%. Bioassays to determine lethal concentrations indicated that concentrations of 600 IJ/ml (H. bacteriophora HB) and 1,000 IJ/ml (S. brazilense IBCB-n06) showed the highest virulence against C. capitata pupae. In contrast, the highest numbers of IJs emerged at concentrations of 1,200 and 200 IJ/ml. In compatibility bioassays, malathion, spinetoram, phosmet, acetamiprid, and novaluron were considered compatible with and harmless (Class 1) to H. bacteriophora HB and S. brazilense IBCB-n06, according to IOBC/WPRS. This information is important for implementing integrated management programs for C. capitata, using biological control with EPNs, whether alone or in combination with chemical insecticides.

Irradiation dose does not affect male reproductive organ size, sperm storage, and female remating propensity in Ceratitis capitata

The Mediterranean fruit fly Ceratitis capitata is a globally invasive pest, often controlled with the sterile insect technique (SIT). For the SIT, mass-rearing of the target insect followed by irradiation are imperatives. Sterile males are often less able to inhibit female remating and transfer less number of sperm, and even irradiation could affect male reproductive organs, with consequences for their ability to inhibit female remating. On the other hand, male age could affect their ability to modulate female response after mating. Here, we evaluated the quality of the genetic sexing strain Vienna-8-tsl mass-reared in Bioplanta San Juan, Argentina, under laboratory conditions, with regard to: (i) the ability of sterile males irradiated at 100 or 140 Gy to inhibit female remating, in the same day and at 24 h of first copulation; (ii) the ability of 3, 4 or 5 day-old sterile males to inhibit female remating at 24 h of first copulation, and (iii) the effect of a reduction in irradiation doses on the number of sperm stored by females and reproductive organ size in virgin males. Sterile males were better able than wild males to inhibit female remating in the same day of first copulation and as able as wild males 1 day after first copulation. Male age did not affect their ability to inhibit female receptivity. Number of sperm stored by females, testes size and ectodermal accessory glands size were not affected by male identity, while sterile 100 Gy males had larger mesodermal accessory glands than control lab males. A reduction in irradiation dose does not impact any variable measured, except for percentage of sperm-depleted females: females mated with sterile 100 Gy males had lower probabilities to store sperm. The results showed here are very encouraging for tsl Vienna 8 strain reared in Argentina and are discussed in comparison with previous studies in C. capitata female remating with dissimilar results.

Distinctive egg-laying patterns in terminal versus non-terminal periods in three fruit fly species

The specific objective of this study was to use a logistic regression model for determining the degree to which egg laying patterns of individual females at the end of life (i.e., terminal segments) in each of three different fruit fly species could be distinguished from the egg-laying patterns over a similar period in midlife (i.e., non-terminal segments). Extracting data from large-scale databases for 11-day terminal and 11-day non-terminal segments in the vinegar fly (Drosophila melanogaster), the Mexican fruit fly (Anastrepha ludens) and the Mediterranean fruit fly (Ceratitis capitata) and organizing the model's results in a 2 × 2 contingency table, we found that: (1) daily egg-laying patterns in fruit flies can be used to distinguish terminal from non-terminal periods; (2) the overall performance metrics such as precision, accuracy, false positives and true negatives depended heavily on species; (3) differentiating between terminal and non-terminal segments is more difficult when flies die at younger ages; and (4) among the three species the best performing metrics including accuracy and precision were those produced using data on D. melanogaster. We conclude that, although the reliability of the prediction of whether a segment occurred at the end of life is relatively high for most species, it does not follow precisely predicting remaining life will also be highly reliable since classifying an end of life period is a fundamentally different challenge than is predicting an exact day of death.

Evaluation of Rearing Parameters of a Self-Limiting Strain of the Mediterranean Fruit Fly, Ceratitis capitata (Diptera: Tephritidae)

The Mediterranean fruit fly (medfly), Ceratitis capitata, is a significant pest of stone and pome fruit that causes considerable economic losses worldwide. Current control is primarily based on insecticides, which are often mixed with protein baits. Oxitec has developed a self-limiting medfly strain (OX3864A) that demonstrates conditional female-specific mortality in the early life stages. Sustained release of OX3864A males offers medfly control, which should lead to substantial economic benefits in area-wide programmes. In the current study, the optimum quantities of mature and immature stages of the strain are assessed under semi-mass production. Moreover, the rearing and quality control limitations related to the production of this strain are provided. The data here demonstrate that the egg hatch rate can reach >85% under optimum rearing conditions. However, this depends on the number of pupae loaded in a cage and their ages. The suggested pupal density ranges between 14,000 and 18,000 pupae per cage to provide optimum egg production. In parallel, the embryo densities of 1.25-1.5 mL/kg larval Tet+ diet are recommended for strain propagation, while embryo densities of 1.25-2.0 mL/kg larval Tet- diet are suggested for male-only pupal production.

Radiation on Medfly Larvae of tsl Vienna-8 Genetic Sexing Strain Displays Reduced Parasitoid Encapsulation in Mass-Reared Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

Improvements in the mass rearing of Diachasmimorpha longicaudata (Ashmead) on larvae of the Vienna-8 temperature-sensitive lethal genetic sexing strain of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) (= GSS Vienna-8) at the San Juan biofactory, Argentina, are currently under way. Lowering cost production is a key factor regarding parasitoid rearing. Thus, the variation in mass-reared parasitoid encapsulation levels and the incidence of superparasitism were determined; also, the gamma radiation dose-effect relation on host larvae and the influence of Mediterranean fruit fly strain were considered. Naked Mediterranean fruit fly larvae of both GSS Vienna-8 and a wild bisexual strain (= WBS) aged 6-d-old were irradiated at 0, 20, 40, 60, 80, 100, and 120 Gy, and exposed to parasitoid females. Melanization level was tested for encapsulated parasitoid larval first-instars (= L1). Non-irradiated and irradiated WBS larvae at 20-40 Gy displayed a significantly higher incidence of encapsulation when compared with GSS Vienna-8 larvae. The low melanized level in encapsulated parasitoid L1 was the most common melanization process at 72 h puparium dissection. A high melanized level was only found in non-irradiated WBS larvae. Irradiated GSS Vienna-8 larvae can neutralize the host immunological reactions over irradiated WBS larvae much more quickly. Superparasitism intensity in both Mediterranean fruit fly strains was not affected by radiation doses. High levels of superparasitism seemingly helped to overcome the host's immune reaction by the surviving parasitoid larva. Parasitoid emergence increased from 60 Gy onwards in both Mediterranean fruit fly strains. Radiation in GSS Vienna-8 larvae may favor host's antagonistic reactions decrease in relation with D. longicaudata development.

Development and Validation of Real-Time PCR Method to Estimate Stored Sperm in the Spermathecae of Ceratitis capitata (Diptera: Tephritidae)

The development of polymerase chain reaction (PCR) markers to identify the Y chromosome of Ceratitis capitata Wiedemann has permitted the detection of sperm transferred to females during mating. However, a molecular technique to quantify the sperm transferred has not yet become available. The current method to quantify the amount of sperm has been the direct counting of sperm heads. Thus, the purpose of this research was to develop and validate an accurate molecular method of diagnosis based on the application of an absolute quantitative real-time PCR, which allows the assessment of the quantity of sperm stored in the spermathecae. For this, Y-specific sequences were used to re-design and test distinct sperm markers. From the amplification product of samples detected as strong positives in conventional PCR, a cloning process of the target sequence was carried out to build the required standard curve. A series of known dilutions of this standard material was prepared for the absolute quantification process. A Roche Lightcycler 480 Real-Time PCR System and SYBRGreen fluorescent dye were used to quantify the sperm contained in the spermathecae of 4-d-old mated females and virgins. Wild-type and Vienna-8 strain sterile males were used to quantify the sperm transferred at four mating durations (10, 30, 60, and 90 min) under laboratory conditions. To validate the reported quantitative method, our results were compared by counting sperm heads under a fluorescent microscope using the same experimental design. In addition, DNA samples were also evaluated and compared by conventional PCR.

Chemical Characterization and Biological Activity of the Mastic Gum Essential Oils of Pistacia lentiscus Var. Chia from Turkey

The essential oils (EOs) were isolated by hydrodistillation from wild and cultivated Pistacia lentiscus L. var. chia-mastic gum tree (Anacardiaceae) from two natural habitats, namely from Cesme-Uzunkoy (1) and Mordogan (2), and one cultivated source, Cesme-Germiyan (3), in Izmir, Turkey. This comparative study evaluated the chemical composition and biological activity of mastic gum essential oils (MGEOs). For this purpose, MGEOs 1-3 were analyzed by gas chromatography-flame ionization detection (GC-FID), gas chromatography-mass spectrometry (GC-MS), and chiral GC for α-pinene. Laboratory assays were conducted to assess for potential in vitro cytotoxicity (multiple in vitro cancer cell lines), antimicrobial properties (five bacterial species and yeast), anti-inflammatory activity (inhibition of inducible nitric oxide synthase, iNOS), and the attraction of Ceratitis capitata (Mediterranean fruit fly, medfly), respectively. Chemical analysis indicated that MGEOs 1 and 2 were rich in α-pinene (56.2% and 51.9%), myrcene (20.1% and 18.6%), and β-pinene (2.7% and 3.1%), respectively; whereas MGEO-3 was characterized by a high level of α-pinene (70.8%), followed by β-pinene (5.7%) and myrcene (2.5%). Chiral GC analyses showed that concentration ratios between (-)/(+)-α-pinene and (-)-α-pinene/myrcene allowed for differentiation between wild and cultivated MGEO sources. In biological assays, MGEOs 1-3 did not exhibit significant antimicrobial effects against the pathogens evaluated and were not strong attractants of male medflies; however, all three MGEOs displayed a dose-dependent inhibition of iNOS, and MGEOs 1 and 2 exhibited selective in vitro cytotoxicity against human cancer cells. These results suggest that wild-type mastic gum oils from Cesme and Mordogan (MGEOs 1 and 2) are potential sources of beneficial products and warrant further investigation.

Cold Responses of the Mediterranean Fruit Fly Ceratitis capitata Wiedemann (Diptera: Tephritidae) in Blueberry

In this study, the effects of cold treatment at 1.0 ± 0.2 °C were investigated on the eggs of the 1st, 2nd, and 3rd instar larvae of Ceratitis capitata in two Australian blueberry cultivars C99-42 and C00-09. Pupariation, emerged adults, and sex ratios were examined on C. capitata after the treatment. The results showed that exposure time at low temperatures was a key factor to affect pupariation and adult emergence. Eleven days of exposure to cold treatment at 1.0 ± 0.2 °C were enough to eradicate all four immature stages in both cultivars. Cold tolerance of the four C. capitata stages was not affected when reared on two different blueberry cultivars. The third instar larva is the most tolerant stage for cold treatment in two blueberry cultivars. There were no significant differences in sex ratios from surviving C. capitata among different stages after treatment. This study improves understanding of C. capitata responses to cold treatment in blueberries, which may contribute to phytosanitary required quarantine treatment of this destructive horticulture pest species.

Toxicities of Insecticidal Toxic Baits to Control Ceratitis capitata (Diptera: Tephritidae): Implications for Field Management

Ceratitis capitata (Wiedemann, 1824) is a significant insect pest of fruits produced worldwide and is capable of causing direct and indirect damage to fruit. Chemical control is the most frequently used management strategy, mainly involving organophosphate insecticides. However, the frequent use of this chemical group has resulted in unacceptable chemical residues on fruits. In this study, the toxicity of 18 insecticides was evaluated in adults and larvae of C. capitata in a laboratory. The organophosphate insecticides chlorpyrifos (Lorsban 480BR), phosmet (Imidan 500WP), and malathion (Malathion 1000EC); the spinosyns spinetoram (Delegate 250WG) and spinosad (Tracer); and the pyrethroid alpha-cypermethrin (Fastac 100SC) caused high mortality (>80%) in C. capitata adults in topical application bioassays and by ingestion when mixed with Biofruit 5% food lures. However, the insecticides chlorfenapyr (Pirate), spinetoram and chlorpyrifos produced a significant reduction in larval infestation of the fruits (67, 74, and 84% larval mortality, respectively). Insecticides based on spinosyns, alpha-cypermethrin, and cyantraniliprole are alternatives that can replace organophosphates in the management of C. capitata in the field.

The Survival of Mediterranean Fruit Fly (Diptera: Tephritidae) Over Winter in Western Australia

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is one of the most economically important pest insects of fruit crops worldwide. Mediterranean fruit fly can cause up to 100% crop loss in susceptible fruit. In order to formulate best management practices, it is critical to understand how Mediterranean fruit fly overwinters in a given geographical location and bridge the gap between autumn and spring populations. In this study, we evaluated the overwintering potential of Mediterranean fruit fly immature and adult stages in two locations in Perth Hills, Western Australia. We also monitored wild adult Mediterranean fruit fly populations for 2 yr. Adults were present year-round with captures very low in winter to early spring relative to summer and autumn. Field experiments revealed that immature stages in apples (eggs/first instar) and soil (pupae) remained viable in winter, emerging as adults at the onset of warmer weather in spring. In field cages, adults survived 72-110 d, and female laid viable eggs when offered citrus fruit, though only 1-6% eggs survived to emerge as adults. Adults survived longer in field cages when offered live citrus branch. The findings suggest that all Mediterranean fruit fly life stages can survive through mild winter, and surviving adults, eggs in the fruit and/or pupae in the soil are the sources of new population that affect the deciduous fruit crops in Perth. We recommend that Mediterranean fruit fly monitoring is required year-round and control strategies be deployed in spring. Furthermore, we recommend removal of fallen fruit particularly apple and other winter fruit such as citrus.

Toxicities and Residual Effect of Spinosad and Alpha-Cypermethrin-Based Baits to Replace Malathion for Ceratitis capitata (Diptera: Tephritidae) Control

Ceratitis capitata (Wiedemann, 1824) is the main insect pest of fruits worldwide. The objective of this study was to evaluate the toxicity and residual effects of the ready-to-use toxic baits Success 0.02CB (0.24 g of active ingredient [a.i.] per liter of spinosad) and Gelsura (6 g of a.i./liter of alpha-cypermethrin) and to compare them with other food lures containing spinosad and malathion mixed with hydrolyzed protein (Biofruit 5% and Flyral 1.25%), Anamed without dilution or sugarcane molasses (7%) against adult C. capitata in laboratory and greenhouse trials. Ceratitis capitata adults were highly susceptible to all toxic bait formulations (mortality > 80%) until 96 h after exposure. The lowest LT50 (hours) of toxic baits were 2.32 (Gelsura at 4,000 mg/liter), 4.26 (Gelsura at 2,000 mg/liter), 4.28 (Anamed + malathion) and 4.89 (sugarcane molasses + malathion), while formulations containing spinosad (Biofruit, Flyral, Anamed and Success 0.02CB) showed LT50 of approximately 11 h. Without rain, Gelsura (2,000 mg/liter) and all spinosad formulations provided mortality superior to 80% 14 d after application. Gelsura and Anamed + spinosad showed higher resistance to a 5-mm simulated rain, similar to Anamed + malathion, while the other formulations had its efficacy decreased. All toxic baits were effective on adult C. capitata in residual experiments without rain while Anamed + spinosad caused high adult mortality after 5 to 25 mm rains. Gelsura and Anamed + spinosad can be used to replace toxic baits containing malathion for C. capitata population management.

Bioassay Method for Toxicity Studies of Toxic Bait Formulations to Ceratitis capitata (Diptera: Tephritidae)

The development of appropriate methodologies for bioassays is of paramount importance to study the methodological factors that may interfere in the experimental design. Thus, laboratory bioassays have become increasingly important for the determination of data that are realistic and replicable. The objective of the study was to develop a bioassay methodology with the ready-to-use toxic bait Success™ 0.02CB, 96 mg L^-1 of spinosad, in adults of Ceratitis capitata (Wiedemann) as a study model. The insect origin (laboratory population, LT₅₀ = 11.16 h), time of toxic bait supply (4 h, LT₅₀ = 16.85 h), food deprivation (12 h, LT₅₀ = 15.55 h), and the adult age (5 days, LT₅₀ = 35.31 h) of C. capitata showed higher susceptibility and a shorter LT₅₀ lethal time to the Success™ 0.02CB toxic bait. However, the absence or presence of a food source (LT₅₀ ≈ 31.17 h) during the bioassay did not affect the susceptibility of C. capitata. Further, adults of C. capitata who were deprived and in the absence of a food source (artificial diet) had higher consumption of toxic baits (mg) during treatment exposure. The use of a 12-h deprivation period, toxic baits offered for 4 h, and absence of an artificial diet for adults of C. capitata at 5 days of age during the bioassay are considered adequate for evaluating formulations of toxic baits under laboratory conditions.

Cold Response of the Mediterranean Fruit Fly (Ceratitis capitata) on a Lab Diet

Cold treatment at 0.0 °C with different exposure durations (0–12 days) was applied to the Mediterranean fruit fly Ceratitis capitata (Wiedemann) fed on a lab diet. The examined developmental stages were early eggs (<6 h), late eggs (>42 h), first instar, second instar and third instar larvae. Pupation, adult emergence and sex ratios of survived flies were investigated to study the C. capitata responses to this low temperature treatment. Our results showed that exposure time at low temperature has a clear effect on pupation and adult emergence. Based on pupation ratios, the first and third instar are the most cold tolerant stages, with LT99 = 7.3 for both of them. Cold tolerance at both stages are very close and no significant differences were detected. There were no significant differences on C. capitata sex ratios among different stages after treatment. This study improves our understanding of C. capitata responses to cold treatment, which may assist in the improvement of the current treatment strategies to control this destructive horticulture pest species.

Application of Direct Immersion Solid-Phase Microextraction (DI-SPME) for Understanding Biological Changes of Mediterranean Fruit Fly (Ceratitis capitata) During Mating Procedures

Samples from three different mating stages (before, during and after mating) of the Mediterranean fruit fly Ceratitis capitata were used in this experiment. Samples obtained from whole insects were subjected to extraction with the two mixtures of solvents (acetonitrile/water (A) and methanol/acetonitrile/water (B)) and a comparative study of the extractions using the different solvents was performed. Direct immersion-solid phase microextraction (DI-SPME) was employed, followed by gas chromatographic-mass spectrometry analyses (GC/MS) for the collection, separation and identification of compounds. The method was validated by testing its sensitivity, linearity and reproducibility. The main compounds identified in the three different mating stages were ethyl glycolate, α-farnesene, decanoic acid octyl ester, 2,6,10,15-tetramethylheptadecane, 11-tricosene, 9,12-(Z,Z)-octadecadienoic acid, methyl stearate, 9-(Z)-tricosene, 9,11-didehydro-lumisterol acetate; 1,54-dibromotetrapentacontane, 9-(Z)-hexadecenoic acid hexadecyl ester, 9-(E)-octadecenoic acid and 9-(Z)-hexadecenoic acid octadecyl ester. The novel findings indicated that compound compositions were not significantly different before and during mating. However, new chemical compounds were generated after mating, such as 1-iodododecane, 9-(Z)-tricosene and 11,13-dimethyl-12-tetradecen-1-acetate which were extracted with both (A) and (B) and dodecanoic acid, (Z)-oleic acid, octadecanoic acid and hentriacontane which were extracted with (A) and ethyl glycolate, 9-hexadecenoic acid hexadecyl ester, palmitoleic acid and 9-(E)-octadecenoic acid, which were extracted with solvent (B). This study has demonstrated that DI-SPME is useful in quantitative insect metabolomics by determining changes in the metabolic compounds in response to mating periods. DI-SPME chemical extraction technology might offer analysis of metabolites that could potentially enhance our understanding on the evolution of the medfly.

Highly efficient genome editing by homology-directed repair using Cas9 protein in Ceratitis capitata

The Mediterranean fruit fly Ceratitis capitata is a highly polyphagous and invasive insect pest, causing enormous economic damage in horticultural systems. A successful and environment-friendly control strategy is the sterile insect technique (SIT) that reduces pest populations through infertile matings with mass-released, sterilized insects. However, the SIT is not readily applicable to each pest species. While transgenic approaches hold great promise to improve critical aspects of the SIT to transfer it to new species, they are suspect to strict or even prohibitive legislation regarding the release of genetically modified (GM) organisms. In contrast, specific mutations created via CRISPR-Cas genome editing are not regulated as GM in the US, and might thus allow creating optimal strains for SIT. Here, we describe highly efficient homology-directed repair genome editing in C. capitata by injecting pre-assembled CRISPR-Cas9 ribonucleoprotein complexes using different guide RNAs and a short single-stranded oligodeoxynucleotide donor to convert an enhanced green fluorescent protein in C. capitata into a blue fluorescent protein. Six out of seven fertile and individually backcrossed G0 individuals generated 57-90% knock-in rate within their total offspring and 70-96% knock-in rate within their phenotypically mutant offspring. Based on the achieved efficiency, this approach could also be used to introduce mutations which do not produce a screenable phenotype and identify positive mutants with a reasonable workload. Furthermore, CRISPR-Cas HDR would allow to recreate mutations formerly identified in classical mutagenesis screens and to transfer them to related species to establish new (SIT-like) pest control systems. Considering the potential that CRISPR-induced alterations in organisms could be classified as non-GM in additional countries, such new strains could potentially be used for pest control applications without the need to struggle with GMO directives.

Identification of Ceratitis capitata (Diptera: Tephritidae) Sperm From Females in Traps: The Importance of the Ventral Receptacle

The monitoring of a pest population often relies on the identification of individuals from traps. For area-wide programs utilizing the sterile insect technique, the further identification of the mated status of females found in traps is of utmost importance. For the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), this is usually verified through the assessment of sperm in the spermathecae. However, this can be misleading for species where there are other sperm storage organs such as the ventral receptacle. Here, we studied the relative importance of sperm storage in the ventral receptacle compared to the spermathecae for females from 5 to 18 d of age. Furthermore, we studied how sperm can be identified in the ventral receptacle or spermathecae after females were recovered from traps. We found no effect of female age on likelihood of sperm storage. Sperm could be identified in both sperm storage organs at 7 or 14 d after females had been placed in traps. We found that the ventral receptacle is a more reliable indicator of female mated status. Thus, we propose that if no sperm are found in the spermathecae, program managers should revise the ventral receptacle before assuming that females are not mated. This test may also be relevant to other pest tephritids that store even more sperm in the ventral receptacle than C. capitata.

Evaluation of predicted Medfly ( Ceratitis capitata) quarantine length in the United States utilizing degree-day and agent-based models

Invasions by pest insects pose a significant threat to agriculture worldwide. In the case of Ceratitis capitata incursions on the US mainland, where it is not officially established, repeated detections are followed by quarantines and treatments to eliminate the invading population. However, it is difficult to accurately set quarantine duration because non-detection may not mean the pest is eliminated. Most programs extend quarantine lengths past the last fly detection by calculating the amount of time required for 3 generations to elapse under a thermal unit accumulation development model (“degree day”). A newer approach is to use an Agent-Based Simulation (ABS) to explicitly simulate population demographics and elimination. Here, predicted quarantine lengths for 11 sites in the continental United States are evaluated using both approaches. Results indicate a strong seasonality in quarantine length, with longer predictions in the second half of the year compared with the first; this pattern is more extreme in degree day predictions compared with ABS. Geographically, quarantine lengths increased with latitude, though this was less pronounced under the ABS. Variation in quarantine lengths for particular times and places was dramatically larger for degree day than ABS, generally spiking in the middle of the year for degree day and peaking in second half of the year for ABS. Analysis of 34 C. capitata quarantines from 1975 to 2017 in California shows that, for all but two, quarantines were started in the second half of the year, when degree day quarantine lengths are longest and have the highest uncertainty. For a set of hypothetical outbreaks based on these historical quarantines, the ABS produced significantly shorter quarantines than degree day calculations. Overall, ABS quarantine lengths were more consistent than degree day predictions, avoided unrealistically long values, and captured effects of rare events such as cold snaps.

Cold Disinfestation of "Hass" Avocado (Persia americana) of Three Species of Fruit Fly (Diptera: Tephritidae)-Ceratitis capitata, Ceratitis rosa, and Ceratitis cosyra

The avocado industry is important in South Africa, but access to certain markets is impeded by the presence of phytosanitary pests. One of the ways of securing entry to these markets is to demonstrate that a mitigating treatment will result in there being a negligible chance of accidental importation. In cold treatment comparative studies at 0 °C and 2 °C of immature stages of Ceratitis capitata (Wiedemann), Ceratitis rosa Karsch, and Ceratitis cosyra (Walker) in "Hass" avocado, the third instar of C. cosyra was shown to be the most cold tolerant. This larval life stage was used in a large-scale trial to test treatment efficacy at 2 °C, a temperature known to be the better for fruit quality. There were no survivors from the 49,795 individual fruit fly larvae subjected to the cold treatment at 2 °C for 20 d. It is argued that, although this level of assessment falls short of the Probit 9 level normally required for fruit fly, they are rarely found in avocado fruit and that the level of disinfestation obtained is more than sufficient to achieve quarantine security.

Analysis of Seasonal Risk for Importation of the Mediterranean Fruit Fly, Ceratitis capitata (Diptera: Tephritidae), via Air Passenger Traffic Arriving in Florida and California

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is one of the most economically damaging pests in the world and has repeatedly invaded two major agricultural states in the United States, Florida and California, each time requiring costly eradication. The Mediterranean fruit fly gains entry primarily in infested fruit carried by airline passengers and, since Florida and California each receive about 13 million international passengers annually, the risk of Mediterranean fruit fly entering the United States is potentially very high. The risk of passengers bringing the pest into Florida or California from Mediterranean fruit fly-infested countries was determined with two novel models, one estimated seasonal variation in airline passenger number and the other defined the seasonal and spatial variability in Mediterranean fruit fly abundance. These models elucidated relationships among the risk factors for Mediterranean fruit fly introduction, such as amount of passenger traffic, routes traveled, season of travel, abundance of Mediterranean fruit fly in countries where flights departed, and risk of the pest arriving at destination airports. The risk of Mediterranean fruit fly being introduced into Florida was greatest from Colombia, Brazil, Panama, Venezuela, Argentina, and Ecuador during January-August, whereas primarily the risk to California was from Brazil, Panama, Colombia, and Italy in May-August. About three times more Mediterranean fruit flies were intercepted in passenger baggage at airports in Florida than California, although the data were compromised by a lack of systematic sampling and other limitations. Nevertheless, this study achieved the goal of analyzing available data on seasonal passenger flow and Mediterranean fruit fly population levels to determine when surveillance should be intensified at key airports in Florida and California.

Population Fluctuation of Ceratitis capitata (Diptera: Tephritidae) as a Function of Altitude in Eastern Guatemala

Population fluctuations of Ceratitis capitata (Wiedemann) were evaluated over a period of 12 mo in four altitudinal strata (400-750, 750-1,100, 1,100-1,450, and 1,450-1,800 meters above sea level, masl) in Eastern Guatemala. Within each altitudinal range, sampling plots were established in coffee plantations and adjacent areas, in which Jackson traps were set and baited with Trimedlure. Coffee berries and other host fruits were collected. Population density was lowest at the 400-750 masl stratum and highest at 1,450-1,800 masl. At every altitudinal range, the fluctuations of the pest were associated mainly with the availability of ripe coffee berries as a primary host. From 750-1,450 masl, the pest was also associated with the availability of sweet orange and mandarins in commercial and backyard orchards. The highest densities of the pest were recorded in the dry season. Citrus were the main alternate host where ripe coffee berries were not available. This knowledge on population dynamics of C. capitata will contribute to develop more effective area-wide pest management strategies including the use of sterile insects, natural enemies, and bait sprays.

Description of third instar larvae of Ceratitis fasciventris, C. anonae, C. rosa (FAR complex) and C. capitata (Diptera, Tephritidae)

Third instar larvae of members of the Ceratitis FAR complex, including Ceratitis fasciventris (Bezzi), Ceratitis anonae Graham, and Ceratitis rosa Karsch are described and compared with those of Ceratitis capitata (Wiedemann). Diagnostic characters, such as presence vs. absence of a secondary tooth on the mandibles, previously used to separate Ceratitis capitata from Ceratitis rosa, are shown to vary in each species. Significant variation in diagnostic morphological characters among populations of Ceratitis rosa from east and south Africa is documented; however, the differences are not simply congruent with the R1 and R2 designations based on other studies. Quantitative measures of numerous morphological characters are consistently smaller in the larvae of Ceratitis fasciventris and distinguish them from other species of the FAR complex. Larvae of Ceratitis capitata can be distinguished from those of the FAR complex by characters such as absence of accessory plates of the oral ridges, the shape of the anterior spiracle, and the pattern of dorsal spinules. Previous studies indicated that absence of accessory lobes separate the genus Ceratitis from Bactrocera, but this is shown to be incorrect, as accessory lobes are in fact present in several species of Ceratitis.

Threshold Concentration of Limonoids (Azamax) for Preventing Infestation by Mediterranean Fruit Fly (Diptera: Tephritidae)

This study identified the threshold concentration of limonoids for the complete inhibition of oviposition of Ceratitis capitata (Wiedemann) in grapes 'Itália.' Choice and no-choice experiments with the insect were performed. The three no-choice bioassays were conducted following a completely randomized design with 18 treatments (three densities of insects [one, two, or three females]×five concentrations of limonoids and control) and 20 replicates. In a free choice bioassay, two fruits per cage (a treatment grape and a control) were provided for ovipositing. Three densities of insects (one, two, or three females) were used, with 15 replicates. Bioassays were conducted at 25±2°C, 60±10% relative humidity, and a photoperiod of 14:10 (L:D) h. The inhibition of oviposition of C. capitata was concentration dependent, with infestation occurring at lower concentrations of azadirachtin (+3-tigloylazadirachtol) and complete inhibition occurring at concentrations at or exceeding 100 ppm azadirachtin (+28.5 ppm of 3-tigloylazadirachtol), maintaining protective effects even at the most densely populated treatment (three females per fruit). When the pest had a free choice of host grapes (treatment vs. control), severe inhibition was observed at concentrations≥50 ppm azadirachtin (+14.3 ppm of 3-tigloylazadirachtol). We conclude that a threshold concentration of 100 ppm azadirachtin (+28.5 ppm of 3-tigloylazadirachtol) is capable of preventing grape infestation. This concentration is likely to provide a reliable level of protection, as the experimental population density of three females per fruit usually does not occur in the field and wild flies usually have more host options.

Detection of the Acetylcholinesterase Insecticide Resistance Mutation (G328A) in Natural Populations of Ceratitis capitata

Wild Mediterranean fruit fly specimens collected from various regions worldwide were screened for the glycine to alanine (Gly->Ala) point mutation (G328A) in the acetylcholinesterase enzyme, presumably causing resistance to organophosphates. We found that the single nucleotide polymorphism (SNP) responsible for this amino acid change is located at the beginning of exon 6 of the Ccace2 gene. The identification of the exact location of the SNP permitted PCR primer design around this site and direct sequencing of the corresponding genomic region. We detected the resistance allele in natural Mediterranean fruit fly populations from Brazil and Spain, but not from other sites in four continents. The known treatment history of sites suggests that the resistance buildup is linked to organophosphate application in the field. The PCR-based detection provides a screening method useful for monitoring Mediterranean fruit fly insecticide resistance in local populations and improving pest management strategies accordingly.

Effects of within-generation thermal history on the flight performance of Ceratitis capitata: colder is better

The influence of thermal history on temperature-dependent flight performance was investigated in an invasive agricultural pest insect, Ceratitis capitata (Diptera: Tephritidae). Flies were exposed to one of four developmental acclimation temperatures (Tacc: 15, 20, 25, 30°C) during their pupal stage and tested at these temperatures (Ttest) as adults using a full-factorial study design. Major factors influencing flight performance included sex, body mass, Ttest and the interaction between Ttest and Tacc. Successful flight performance increased with increasing Ttest across all acclimation groups (from 10% at 15°C to 77% at 30°C). Although Tacc did not affect flight performance independently, it did have a significant interaction effect with Ttest. Multiple comparisons showed that flies which had been acclimated to 15°C and 20°C performed better than those acclimated to 25°C and 30°C when tested at cold temperatures, but warm-acclimated flies did not outperform cold-acclimated flies at warmer temperatures. This provides partial support for the 'colder is better' hypothesis. To explain these results, several flight-related traits were examined to determine whether Tacc influenced flight performance as a consequence of changes in body or wing morphology, whole-animal metabolic rate or cytochrome c oxidase enzyme activity. Although significant effects of Tacc could be detected in several of the traits examined, with an emphasis on sex-related differences, increased flight performance could not be explained solely on the basis of changes in any of these traits. Overall, these results are important for understanding dispersal physiology despite the fact that the mechanisms of acclimation-related changes in flight performance remain unresolved.

Population Dynamics of the Mediterranean Fruit Fly in Montenegro

Population dynamics of the Mediterranean fruit fly was studied along Montenegro seacoast. Tephri traps baited with 3 component female-biased attractants were used in 11 different localities to monitor the fruit fly population in commercial citrus orchards, mixed-fruit orchards, and in backyards. From 2008-2010, the earliest captures were recorded no earlier than July. In 2011, the first adult fly was detected in mid-June. Low captures rates were recorded in July and August (below 0.5 flies per trap per day; FTD) and peaked from mid-September to the end of October of each year. Our results indicate fluctuation of fly per trap per day depending on dates of inspection and locality, with significant differences in the adult population density. A maximum population was always reached in the area of Budva-Herceg Novi with an FTD of 66.5, 89.5, 71.63, and 24.64 (from 2008-2011 respectively). Fly activity lasts from mid-June/early-July to end December, with distinct seasonal variation in the population.