N-Butyl sulfide as an attractant and coattractant for male and female codling moth (Lepidoptera: Tortricidae)

Male and Female Tortricid Moth Response to Non-Pheromonal Semiochemicals

In eastern North America, apple orchards are often attacked by several species of tortricid moths (Lepidoptera), including Cydia pomonella, Grapholita molesta, Argyrotaenia velutinana, and Pandemis limitata. Sex pheromones are routinely used to monitor male moth populations. Adding plant volatiles to monitoring traps could increase the capture of moths of both sexes and improve the effectiveness of mating disruption systems. This study sought to quantify the attraction of adults of four tortricid moth species to five olfactory treatments, namely (1) Pherocon® CM L2-P, (2) Pherocon Megalure CM 4K Dual® (=Megalure), (3) Megalure + benzaldehyde, (4) TRE 2266 (linalool oxide + (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT)), and (5) TRE 2267 (linalool oxide + DMNT + benzaldehyde), in non-mating disrupted commercial apple orchards in Massachusetts. The commercial lure Megalure was attractive to both sexes of G. molesta and C. pomonella. The addition of benzaldehyde to TRE 2266 or to Megalure significantly increased the capture of male G. molesta during the mid and late season of 2021. Only when benzaldehyde was added to TRE 2266 did the latter lure attract P. limitata in 2020 and 2021. The greatest number of tortricid moths (all four species combined) was captured by TRE 2267. This finding highlights the opportunity to enhance the attractiveness of a commercial lure through the addition of benzaldehyde, an aromatic compound, to Megalure. The potential of these additional volatiles to detect moths in a mating-disrupted orchard and/or remove female moths as a component of a management system is discussed.

Research of Synergistic Substances on Tobacco Beetle [Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae)] Adults Attractants

In this study, four kinds of chemical substances (2,3,5,6-tetramethylpyrazine, β-ionone, citronellal, and paeonol), three kinds of plant essential oils (tea tree essential oil, lavender essential oil, and myrrh essential oil), and their combinations were selected to explore their synergistic effects on tobacco beetle [Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae)] adults by the behavioral test and laboratory simulation test. Behavioral test results showed that some of the combinations revealed a synergistic effect on tobacco beetle adults, especially the sexual attractant +2,3,5,6-tetramethylpyrazine + β-ionone + citronellal + paeonol (SABCD, one portion of sexual attractant, and 1 mg/L synergistic substances) combination and the food attractant +2,3,5,6-tetramethylpyrazine + paeonol (FAD, 1 ml of food attractant and 1 mg/L synergistic substances) combination showed the best behavioral effect on tobacco beetle adults with average dwell times of 120.97 and 126.74 s, respectively, compared to those of other combinations. Meanwhile, SABCD had the highest selection rate [89.47%, about 1.5 times that of the sexual attractant (S)] on tobacco beetle adults compared with those of other combinations. In addition, laboratory simulation test results showed that the SABCD combination had the highest average selection rate (37.31%, about 2 times that of S) on tobacco beetle adults at 1 mg/L. However, our results showed that there was no significant difference in the indoor simulation results of food attractant synergistic substances. Our results will provide guidance for the development of new pesticides for tobacco beetle adults.

Comparison of New Kairomone-Based Lures for Cydia pomonella (Lepidoptera: Tortricidae) in Italy and USA

Simple Summary

Adult codling moth (Cydia pomonella L.) monitoring with lure-baited traps is a prerequisite to effectively manage this key pest in apple and pear crops without over-spraying insecticides. We evaluated new multi-component lures comprised of blends of sex pheromone and volatile organic compounds (pear ester, dimethyl nonatriene and linalool oxide) loaded into different substrates (septa and PVC lures). Acetic acid in a second membrane lure was used as a co-lure with all blends. Lure comparisons were performed during the period 2019/2020 in Italy and Washington State (USA) in orchards treated with or without sex pheromone dispensers for mating disruption. The highest total moth counts occurred with the sex pheromone/pear ester PVC lure in both countries. The new multi-component PVC lure without sex pheromone captured the greatest number of female moths only in the USA. This geographical disparity may limit the effectiveness of using a ‘female removal’ strategy to manage this pest without insecticides across major production areas.

Abstract

Studies were conducted during the period 2019/2020 to evaluate the effectiveness of four lures for codling moth (Cydia pomonella L.) in pome fruits in Italy and the USA. Multi-component blends of sex pheromone ((E,E)-8,10-dodecadien-1-ol, PH), pear ester ((E,Z)-2,4-ethyl decadienoate, PE), (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), and pyranoid linalool oxide (6-ethenyl-2,2,6-trimethyloxan-3-ol, LOX) were loaded in either a halobutyl elastomer septum or a PVC matrix and always used in combination with acetic acid (AA) loaded in a closed membrane co-lure. Total moth capture was significantly greater with the PVC than the septum lure loaded with PH/PE + AA in both countries. Female capture in the USA study was significantly greater for 8 weeks in traps baited with the PE/DMNT/LOX blend + AA co-lure than with other lures and adding PH to this blend in a PVC lure significantly reduced female capture. In contrast, female capture in Italy did not differ among lures and counts were similar in both apple and pear crops treated with or without mating disruption. These results suggest that the effectiveness of ‘female removal’ strategies to manage codling moth may be geographically limited and further comparisons are needed in other production regions and in walnut.

Combined Effects of Mating Disruption, Insecticides, and the Sterile Insect Technique on Cydia pomonella in New Zealand

Simple Summary

Codling moth is a major pest of apples, and was accidentally introduced into New Zealand over 150 years ago. Many countries that New Zealand exports apples to do not have codling moth present and they want to keep it out. Therefore, apple growers must heavily control codling moth populations on their orchards. Currently, the main control tactics are insecticide applications and mating disruption, which uses the moth’s own sex pheromone to make the males unable to find females to mate. We aimed to supplement these tactics with the sterile insect technique (SIT) to further suppress the codling moth on orchards. SIT involves mass rearing and sterilizing codling moth and then releasing them onto orchards where they mate with wild insects resulting in no offspring. We released sterile insects onto seven orchards using unmanned aerial vehicles and ground releases. Six years of the program saw significant drops (90–99%) in wild moth populations. The SIT is an excellent tactic for reducing moth populations in export apple orchards.

Abstract

Codling moth was introduced into New Zealand, and remains a critical pest for the apple industry. Apples exported to some markets require strict phytosanitary measures to eliminate the risk of larval infestation. Mating disruption and insecticide applications are the principal means of suppression in New Zealand. We tested the potential for the sterile insect technique (SIT) to supplement these measures to achieve local eradication or suppression of this pest. SIT was trialed in an isolated group of six integrated fruit production (IFP) orchards and one organic orchard (total 391 ha), using sterilized insects imported from Canada, with release by unmanned aerial vehicle and from the ground. Eradication was not achieved across the region, but a very high level of codling moth suppression was achieved at individual orchards after the introduction of sterile moths in combination with mating disruption and larvicides. After six years of releases, catches of wild codling moths at three IFP orchards (224 ha) were 90–99% lower than in 2013–2014, the year before releases began. Catches at three other IFP orchards (129 ha) decreased by 67–97% from the year before releases began (2015–2016), from lower initial levels. At a certified organic orchard with a higher initial population under only organic larvicides and mating disruption, by 2019–2020, there was an 81% reduction in wild moths capture from 2016–2017, the year before releases began.

A Codling Moth (Lepidoptera: Tortricidae) Kairomonal Lure Is Marginally Effective at Decreasing Fruit Damage in Apple Trees Outside of Orchard Settings

Codling moth, Cydia pomonella (L.), is a significant pest of pome fruits and walnuts worldwide. Recently, a three-chemical kairomonal lure, comprised of pear ester, acetic acid, and n-butyl sulfide, was successfully used as an attractant in a mass-trapping scheme to reduce fruit damage in commercial apple orchards. In this study, we tested whether this same attractant could be used outside of an orchard setting to decrease fruit damage in isolated, unmanaged apple (Malus spp.) (Rosales: Rosaceae) trees. Traps containing the lures were placed in trees before the first codling moth flight and maintained throughout the summer. We found that while the traps statistically reduced the percent of apples damaged near the trap, the effect was smaller than expected and limited to areas near the trap. It is currently unclear, but site-specific effects (e.g., host type, apple density, codling moth source) may be important factors in the efficacy of management tools in these systems. While kairomone-based trapping could be a practical and feasible management tool in individual trees outside of orchards, more work needs to be done to understand the limitations of this method.

The ecology of insect-yeast relationships and its relevance to human industry

Many species of yeast are integral to human society. They produce many of our foods, beverages and industrial chemicals, challenge us as pathogens, and provide models for the study of our own biology. However, few species are regularly studied and much of their ecology remains unclear, hindering the development of knowledge that is needed to improve the relationships between humans and yeasts. There is increasing evidence that insects are an essential component of ascomycetous yeast ecology. We propose a 'dispersal-encounter hypothesis' whereby yeasts are dispersed by insects between ephemeral, spatially disparate sugar resources, and insects, in turn, obtain the benefits of an honest signal from yeasts for the sugar resources. We review the relationship between yeasts and insects through three main examples: social wasps, social bees and beetles, with some additional examples from fruit flies. Ultimately, we suggest that over the next decades, consideration of these ecological and evolutionary relationships between insects and yeasts will allow prediction of where new yeast diversity is most likely to be discovered, particularly yeasts with traits of interest to human industry.

A Multiple-Choice Bioassay Approach for Rapid Screening of Key Attractant Volatiles

Fermentation volatiles attract a wide variety of insects and are used for integrated pest management. However, identification of the key behavior modifying chemicals has often been challenging due to the time consuming nature of thorough behavioral tests and unexpected discrepancies between laboratory and field results. Thus we report on a multiple-choice bioassay approach that may expedite the process of identifying field-worthy attractants in the laboratory. We revisited the four-component key chemical blend (acetic acid, ethanol, acetoin, and methionol) identified from 12 antennally active wine and vinegar chemicals for Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). The identification of this blend took 2 yr of continuous laboratory two-choice assays and then similarly designed field trials. This delay was mainly due to a discrepancy between laboratory and field results that laboratory two-choice assay failed to identify methionol as an attractant component. Using a multiple-choice approach, we compared the co-attractiveness of the 12 potential attractants to an acetic acid plus ethanol mixture, known as the basal attractant for D. suzukii, and found similar results as the previous field trials. Only two compounds, acetoin and, importantly, methionol, increased attraction to a mixture of acetic acid and ethanol, suggesting the identification of the four-component blend could have been expedited. Interestingly, the co-attractiveness of some of the 12 individual compounds, including a key attractant, methionol, appears to change when they were tested under different background odor environments, suggesting that background odor can influence detection of potential attractants. Our findings provide a potentially useful approach to efficiently identify behaviorally bioactive fermentation chemicals.

Mass-Trapping Codling Moth, Cydia pomonella (Lepidopteran: Torticidae), Using a Kairomone Lure Reduces Fruit Damage in Commercial Apple Orchards

Codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) is a major pest of pome fruits worldwide. Fruit is damaged by larval feeding, and numbers of larvae are directly related to the numbers of females in the preceding generation. In Pacific Northwest, apple orchards, C. pomonella are generally managed with insecticides and mating disruption. However, additional control methods are needed when these treatments fail or are undesirable. Using a three-component kairomone lure that attracts both sexes, we mass-trapped C. pomonella in 4-acre plots located within commercial apple orchards. In all cases, there were smaller increases in fruit infestation in the mass-trapped plots than in the corresponding control plots. This relative decrease in fruit infestation in the mass-trapped plots corresponded with the removal of more male and female C. pomonella. Mass-trapping using this lure has potential to be a novel and promising addition to integrated pest management of C. pomonella.

Field Experiment of a Three-Chemical Controlled-Release Dispensers to Attract Codling Moth (Cydia pomonella) (Lepidoptera: Tortricidae)

Male and female codling moths, Cydia pomonella (Lepidoptera: Tortricidae), were shown to be attracted to a three-chemical kairomonal lure consisting of pear ester, acetic acid, and n-butyl sulfide. A controlled-release device based on sachets was developed in the laboratory and field tested to optimize the attractiveness of C. pomonella to this combination of attractants, and to decrease material costs associated with the controlled-release of these chemicals. The lure was most effective when pear ester was released from a separate dispenser than when combined acetic acid and n-butyl sulfide. We found that acetic acid and n-butyl sulfide can be combined into one device without decreasing C. pomonella trap catches and that there is minimal pear release rate before trap catch is negatively affected. A sachet-based controlled-release system of pear ester, acetic acid, n-butyl sulfide is a cost-effective alternative to a vial and septa controlled-release system and allows for easier quantification of ideal release rates. A reduction in material costs associated with management are important in promoting the adoption of attract-and-kill and mass-trapping paradigms for C. pomonella management. These findings also have important consequences in interpreting studies that use different loads of pear ester, and emphasize the need to better understand the release rates of attractants.

Novel Chemo-Attractants for Trapping Tomato Leafminer Moth (Lepidoptera: Gelechiidae)

The tomato leafminer moth, Tuta absoluta (Meyrick), is a devastating pest for tomatoes in Iran and throughout the world. This pest reduces tomato yields in farms and greenhouses. It appears some floral odors are significant attractants for tomato leafminer moth. In this study, the effects of three floral compounds, phenylacetaldehyde (PAA), acetic acid (AA), and 3-methyl-1-butanol (MB), were evaluated as trap attractants for tomato leafminer moth. The attractants were tested separately, combined, and blended in binary and tertiary. Lures were tested in delta and water pan traps under field conditions and compared with unbaited traps as controls. Results indicated that water pan traps caught more moths than delta traps. Also treatments with PAA + AA combined and the AA + MB blend were strongly attractive to tomato leafminer moth males compared with other treatments in this study.

A Binary Host Plant Volatile Lure Combined With Acetic Acid to Monitor Codling Moth (Lepidoptera: Tortricidae)

Field studies were conducted in the United States, Hungary, and New Zealand to evaluate the effectiveness of septa lures loaded with ethyl (E,Z)-2,4-decadienoate (pear ester) and (E)-4,8-dimethyl-1,3,7-nonatriene (nonatriene) alone and in combination with an acetic acid co-lure for both sexes of codling moth, Cydia pomonella (L.). Additional studies were conducted to evaluate these host plant volatiles and acetic acid in combination with the sex pheromone, (E,E)-8,10-dodecadien-1-ol (codlemone). Traps baited with pear ester/nonatriene + acetic acid placed within orchards treated either with codlemone dispensers or left untreated caught significantly more males, females, and total moths than similar traps baited with pear ester + acetic acid in some assays. Similarly, traps baited with codlemone/pear ester/nonatriene + acetic acid caught significantly greater numbers of moths than traps with codlemone/pear ester + acetic acid lures in some assays in orchards treated with combinational dispensers (dispensers loaded with codlemone/pear ester). These data suggest that monitoring of codling moth can be marginally improved in orchards under variable management plans using a binary host plant volatile lure in combination with codlemone and acetic acid. These results are likely to be most significant in orchards treated with combinational dispensers. Significant increases in the catch of female codling moths in traps with the binary host plant volatile blend plus acetic acid should be useful in developing more effective mass trapping strategies.