Repellency of a kaolin particle film, Surround, and a mineral oil, Sunspray oil, to silverleaf whitefly (Homoptera: Aleyrodidae) on melon in the laboratory

Use of paraffin oils in agriculture and beyond: back to the future

Paraffin (petroleum) oils have been used for many years for their insecticidal properties, but relatively little research had been conducted towards their introduction into the agricultural praxis, due to their potential phytotoxic effects. In the recent years, however, there has been an increased interest in petroleum-based pesticides due to their compatibility with integrated pest management (IPM) programs. Various improvements in the refinement methods have enhanced the manufacture of commercial products with many advantageous features over the original oil formulas. However, literature is still lacking of a general overview about the applicability of newly introduced commercial petroleum oils in agriculture and their compatibility with modern pest management practices. Therefore, the present work aims to depict the current status of petroleum oils in arboriculture and beyond, providing an in-depth analysis of their insecticidal properties with respect to the knowledge gained over the years about the factors responsible for the pesticidal efficacy and the phytotoxic activity of petroleum-derived oil insecticides. Moreover, commercial aspects of petroleum oil formulations and their toxicological profile to non-target organisms have also been addressed through the current legislation in EU and the USA.

Mechanical Acaricides Active against the Blacklegged Tick, Ixodes scapularis

Cases of Lyme disease in humans are on the rise in the United States and Canada. The vector of the bacteria that causes this disease is the blacklegged tick, Ixodes scapularis. Current control methods for I. scapularis mainly involve chemical acaricides. Unfortunately, ticks are developing resistance to these chemicals, and more and more, the public prefers non-toxic alternatives to chemical pesticides. We discovered that volcanic glass, Imergard^TM WP, and other industrial minerals such as Celite 610 were efficacious mechanical insecticides against mosquitoes, filth flies, and agricultural pests. In this report, when 6-10- and 50-70-day old unfed I. scapularis nymphs were dipped for 1-2 s into Celite, the time to 50% mortality (LT₅₀) was 66.8 and 81.7 min, respectively, at 30 °C and 50% relative humidity (RH). The LT₅₀ was actually shorter at a higher 70% RH, 43.8 min. Scanning electron microscopy showed that the ticks were coated over most of their body surface, including partial to almost total coverage of the opening to their respiratory system. The other mechanical insecticide, Imergard, had similar efficacy against blacklegged unfed nymphs with an LT₅₀ at 30 °C and 50% RH of 70.4 min. Although more research is needed, this study suggests that industrial minerals could be used as an alternative to chemical pesticides to control ticks and Lyme disease.

Lethal Effects of Commercial Kaolin Dust and Silica Aerogel Dust With and Without Botanical Compounds on Horn Fly Eggs, Larvae, Pupae, and Adults in the Laboratory

The horn fly, Haematobia irritans irritans (L.) (Diptera: Muscidae), is an important bloodsucking ectoparasite of cattle throughout much of the world. The fly is mostly controlled using conventional synthetic insecticides but as concerns about resistance increase, alternative tactics have come under heightened scrutiny. Four desiccant dust products: Surround WP, a kaolin clay-based wettable powder; CimeXa, comprised of silica aerogel; Drione, silica aerogel + pyrethrins; and EcoVia, silica aerogel + thyme oil, were assessed for their lethal effects against horn fly eggs, larvae, pupae, and adults, under laboratory conditions. Although Surround WP and CimeXa did not prevent egg hatching and (when mixed with manure substrate) pupal development, the two products were associated with moderate reductions of emerged adults, and with complete adult contact mortality within 6 hr and 24 hr, respectively. Drione and EcoVia eliminated egg hatching, pupal development, and adults within 15 min to 1 hr, respectively, whether the flies were exposed to treated filter paper substrate or exposed by immersion in the dusts. Implications for horn fly control and advantages of inert desiccant dust formulations are discussed.

Frequency of processed kaolin application to prevent Diaphorina citri infestation and dispersal in flushing citrus orchards

BACKGROUND

Processed kaolin is a promising tactic that can be utilized for managing Diaphorina citri Kuwayama infestation. However, the frequency of kaolin application to protect citrus trees during flushing remains undetermined. The objective of this study was to ascertain the frequency of kaolin application (2%) required to reduce D. citri infestation and dispersal in flushing citrus orchards and to measure the spectral reflectance of kaolin-sprayed leaves.

RESULTS

Trees sprayed with kaolin at 7- and 14-day intervals showed an 80% psyllid reduction compared to untreated trees. In addition, there was lower psyllid dispersal in the kaolin-sprayed plots. Spectral measurements (wavelengths between 320 and 700 nm) showed an increased reflectance of 35.4% (adaxial leaf side) and 21.9% (abaxial leaf side) in mature leaves, and 9% (adaxial leaf side) and 2.2% (abaxial leaf side) in kaolin-sprayed immature leaves compared to untreated trees.

CONCLUSION

Application of kaolin (2%) at 7- and 14-day intervals can be an important and sustainable tool for reducing D. citri infestation and dispersal in flushing citrus orchards. The reduced D. citri population in plots with both kaolin application intervals may be related to the visual effect (whitish aspect) and increased light reflectance in citrus trees, which are probably the main mechanisms by which kaolin interferes on D. citri host finding behavior. © 2021 Society of Chemical Industry.

New thinking for filth fly control: residual, non-chemical wall spray from volcanic glass

Filth flies are of medical and veterinary importance because of the transfer of disease organisms to animals and humans. The traditional control methods include the use of chemical insecticides. A novel mechanical insecticide made from volcanic glass and originally developed to control mosquitoes (Imergard™ WP; ImG) was investigated for control of adult grey flesh flies, Sarcophaga bullata (Parker), secondary screwworms, Cochliomyia macellaria (F.), and house flies, Musca domestica L. In a modified WHO cone test device, the time to 50% mortality (LT₅₀ ) when applied at 5 g/m² (tested at 30 °C and 50% relative humidity (rH)) was 7.1, 4.3 and 3.2 h, respectively. When knockdown was included, the LT₅₀ s were 5.5, 1.5 and 2.8 h, respectively. Application rates of 1.25 and greater g/m² had the shortest LT₅₀ s. The time to the LT₅₀ increased for M. domestica as rH increased, but ImG was still active at the highest rH tested of 70%. Scanning electron micrographs showed ImG was present on all body parts, unlike that for mosquitoes where it was found mostly on the lower legs. These first studies on the use of Imergard WP against flies suggest this could be an alternative method for filth fly control.

Bemisia tabaci on Vegetables in the Southern United States: Incidence, Impact, and Management

Simple Summary

The sweetpotato whitefly, Bemisia tabaci, was initially discovered in the United States in 1894 but was not considered an economic insect pest on various agricultural crops across the southern and western states. After the introduction of B. tabaci Middle East-Asia Minor 1 (MEAM1) into the United States around 1985, the insect rapidly spread throughout the Southern United States to Texas, Arizona, and California. Extreme field outbreaks occurred on vegetable and other crops in those areas. The sweetpotato whitefly is now regarded as one of the most destructive insect pests in vegetable production systems in the Southern United States. The direct and indirect plant damage caused by B. tabaci has led to substantial economic losses in vegetable crops. Bemisia tabaci outbreaks on vegetables in Georgia resulted in significant economic losses of 132.3 and 161.2 million US dollars (USD) in 2016 and 2017, respectively. Therefore, integrated pest management (IPM) tactics are warranted, including cultural control by manipulation of production practices, resistant vegetable varieties, biological control using various natural enemies, and the judicious use of insecticides.

Abstract

Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is among the most economically important insect pests of various vegetable crops in the Southern United States. This insect is considered a complex of at least 40 morphologically indistinguishable cryptic species. Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) was initially introduced in the United States around 1985 and has since rapidly spread across the Southern United States to Texas, Arizona, and California, where extreme field outbreaks have occurred on vegetable and other crops. This pest creates extensive plant damage through direct feeding on vegetables, secreting honeydew, causing plant physiological disorders, and vectoring plant viruses. The direct and indirect plant damage in vegetable crops has resulted in enormous economic losses in the Southern United States, especially in Florida, Georgia, and Texas. Effective management of B. tabaci on vegetables relies mainly on the utilization of chemical insecticides, particularly neonicotinoids. However, B. tabaci has developed considerable resistance to most insecticides. Therefore, alternative integrated pest management (IPM) strategies are required, such as cultural control by manipulation of production practices, resistant vegetable varieties, and biological control using a suite of natural enemies for the management of the pest.

Biopesticides for Management of Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae) and Tomato Yellow Leaf Curl Virus

The sweetpotato whitefly, Bemisia tabaci MEAM1 Gennadius, is a global pest of tomato, transmitting Tomato yellow leaf curl virus (TYLCV). Management of B. tabaci is challenging in part because of its ability to develop resistance to insecticides. Biopesticides include materials that control B. tabaci via mechanisms that do not select for resistance. Field experiments were conducted in the spring and fall of 2016 and 2017 at the University of Florida's Gulf Coast Research and Education Center in west central Florida to compare biopesticides to conventional insecticides for management of B. tabaci and TYLCV. Insecticide rotations were designed in part around the concept that conventional insecticide programs should group modes of action according to 5-wk treatment intervals, corresponding to an estimated 5-wk generation time for the pest. In 2016, when tomato was treated during the first 5-wk treatment interval with either biopesticides or neonicotinoid insecticides, insecticidal soap contributed to a reduction in whitefly egg numbers and percentage TYLCV that was comparable to results achieved with dinotefuran. In contrast, egg numbers and virus incidence in plants treated with kaolin clay tended to be numerically higher than the untreated control. In spring 2017, comparisons of biopesticides and conventional ovicides/nymphicides during the second 5-wk treatment interval showed that biopesticides can provide comparable reduction in nymph numbers to conventional insecticides. While data from these trials confirm that biopesticides can reduce numbers of whitefly eggs and nymphs, they indicate that season-long programs of the biopesticides evaluated may not reduce transmission of TYLCV below economically acceptable levels.

The Influence of Visual and Olfactory Cues in Host Selection for Bemisia tabaci Biotype B in the Presence or Absence of Tomato Yellow Leaf Curl Virus

The silverleaf whitefly, Bemisia tabaci, is one of the most destructive agricultural pests in the world, vectoring a large number of devastating viruses, including Tomato Yellow Leaf Curl Virus (TYLCV). When selecting a host, B. tabaci is primarily influenced by a range of visual and olfactory cues. Therefore, elucidating how such cues become modified in the presence of whitefly-vectored begomoviruses is critical to better understanding the epidemiology of many economically important diseases. The goal of this study was to determine how both visual and odor cues interact in the presence of TYLCV. In Y-tube olfactometer assays, whiteflies were submitted to a range of isolated visual and olfactory cues to determine behavioral changes. B. tabaci choices were then compared to both stimuli combined in the presence or absence of TYLCV. Under visual stimuli only, B. tabaci exhibited a visual attraction to the color yellow, TYLCV-infected tomato leaves, and TYLCV-infected tomato volatiles. Attraction was the strongest overall when both visual and olfactory cues from TYLCV-symptomatic tomato plants were combined, as opposed to a single isolated cue. These results highlight the importance of both sensory stimuli during B. tabaci host selection in the presence of an associated begomovirus.

Processed kaolin affects the probing and settling behavior of Diaphorina citri (Hemiptera: Lividae)

BACKGROUND

Alternative methods that have the potential to reduce the entry of Diaphorina citri Kuwayama (Hemiptera: Liviidae), the major citrus pest worldwide, into commercial groves could be a viable approach for huanglongbing management. Kaolin is an aluminum silicate that when sprayed on plants forms a white particle film that interferes with host recognition by the insects. Diaphorina citri orients towards the host plants by visual and olfactory cues. The purpose of the study was to determine the effect of processed kaolin on D. citri settling (no-choice) and probing behavior [electrical penetration graph (EPG) technique] under laboratory conditions, and to study its host plant finding ability and dispersal under field conditions in the absence and presence of young shoots.

RESULTS

Under laboratory conditions, kaolin caused an overall reduction of 40% in the number of psyllids settled on treated seedlings; furthermore, the proportion of individuals that were able to reach the phloem was 50% lower on kaolin-treated plants than on untreated plants. In the field, the plant finding ability of D. citri was disrupted on kaolin-treated trees (overall reduction of 96%), regardless of the vegetative condition, and psyllid dispersal was slower in kaolin-treated plots than in the untreated control.

CONCLUSION

This study clearly demonstrates that processed kaolin interferes negatively with different aspects of the host plant finding ability of D. citri. These findings suggest that processed kaolin has a high potential to reduce huanglongbing primary infection. © 2018 Society of Chemical Industry.

Thrips counts and disease incidence in response to reflective particle films and conservation tillage in cotton and peanut cropping systems

Feeding damage to seedling cotton and peanut inflicted by adult and immature thrips may result in stunted growth and delayed maturity. Furthermore, adult thrips can transmit Tomato spotted wilt virus (TSWV) to seedling peanut, which reduces plant growth and yield. The objective of this research was to assess the efficacy of inert particle films, calcium carbonate or kaolin, in combination with conservation tillage, to reduce adult and immature thrips counts in cotton and peanut crops. Planting cotton or peanut into strip tillage utilizing a rolled rye winter cover crop significantly reduced immature thrips counts. Furthermore, plant damage ratings in cotton as well as TSWV incidence in peanut significantly decreased under conservation tillage. Aboveground cotton biomass and plant stand in cotton and peanut were unaffected by calcium carbonate or kaolin particle film applications. Within each week, immature thrips counts were unaffected by particle films, regardless of application rate. In cotton plots treated with kaolin, total Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) counts summed across weeks were significantly greater compared to the untreated control. For adult F. fusca counts at 3 weeks after planting, an interaction between tillage and particle film treatments was observed with fewer adult thrips in particle film and strip tillage treated peanut. Similarly, reduced TSWV incidence was observed in particle film-treated peanut grown using conservation tillage. Neither cotton nor peanut yields were affected by particle film treatments.

Kaolin and copper-based products applications: ecotoxicology on four natural enemies

Lethal and sublethal effects of kaolin clays and two copper-based products on four natural enemies found in olive orchards Anthocoris nemoralis (F.) (Hem. Anthocoridae), Chelonus inanitus (L.) (Hym. Braconidae), Chilocorus nigritus (F.) (Col. Coccinellidae) and Scutellysta cyanea Motschulsky (Hym. Pteromalidae) are described. Both kaolin and copper can be applied for controlling the olive fruit fly and the olive moth, two important pests of this crop. The products did not increase the mortality of any of the insects studied, with the exception of A. nemoralis. The sublethal effects, however, differed depending on the parameter evaluated and the insect studied. Both kaolin and coppers slightly, but significantly, reduced the life span of C. inanitus and S. cyanea. Number of eggs laid by A. nemoralis females were reduced, but not significantly compared to the controls. In the behavioural experiments, clear preference for remaining on kaolin-untreated surfaces when insects were able to choose was observed. Despite having some negative effects, the negative impact on natural enemies was lower than the impact caused by products commonly applied in this crop against the pests stated above. Therefore, both kaolin and copper can be considered as alternative products to be applied in olive orchards if an effective resistance management programme is to be developed. Furthermore, both of them are allowed in organic farming, in which the number of products that can be applied is more restricted.

Repellency of a kaolin particle film to potato psyllid, Bactericera cockerelli (Hemiptera: Psyllidae), on tomato under laboratory and field conditions

BACKGROUND

The potato psyllid, Bactericera cockerelli, is a vector of Candidatus Liberibacter solanacearum, causing several diseases in solanaceous crops. Laboratory and field no-choice and choice experiments were conducted to evaluate the repellency of kaolin particle film on adults of B. cockerelli on tomato plants that had been sprayed with kaolin particle film on the upper surface only, on the lower surface only and on both leaf surfaces.

RESULTS

In no-choice tests in the laboratory, the numbers of adults on leaves were not different between the kaolin particle film and the water control, regardless of which leaf surface(s) were treated, but numbers of eggs were lower on the leaves treated with kaolin particle film than on those treated with water. In choice tests on plants treated with water/plants treated with kaolin particle film at ratios of 1:1, 6:3 or 8:1, fewer adults and eggs were found on the leaves treated with kaolin particle film than on leaves treated with water. Under field conditions, in caged no-choice or choice tests, fewer adults, eggs and nymphs were found on plants treated with kaolin particle film than on plants treated with water. In an uncaged test under field conditions, plants sprayed with kaolin particle film had fewer psyllids than those sprayed with water.

CONCLUSION

Even though potato psyllid adults could land on plants treated with kaolin particle film when no choice was given, fewer eggs were laid. When given a choice, the psyllids avoided plants treated with kaolin particle film under laboratory and field conditions. Kaolin particle film treatment may be a useful alternative for management of potato psyllids under field conditions.

Effects of kaolin on Ophelimus maskelli (Hymenoptera: Eulophidae) in laboratory and nursery experiments

Although recent research has demonstrated that clays provide satisfactory control of some agricultural insect pests, the effect of clays on gall wasps that damage forest trees has not been previously reported. The aim of the current study is to evaluate the effectiveness of the clay kaolin in the laboratory and in the field in reducing the damage caused by the eulophid Ophelimus maskelli (Ashmead) on seedlings of eucalyptus (Eucalyptus L'Hér.) species. In the laboratory, kaolin + wetting agent significantly reduced the percentage of infested leaves and the number of galls per leaf. In the nursery, gall number per leaf was not correlated with leaf area with kaolin + wetting agent but was related to leaf area for all other treatments (wetting agent alone, imidacloprid, and untreated control). In the nursery, gall number per leaf was lower with kaolin + wetting agent and with imidacloprid than with the other two treatments. Overall, kaolin effectively reduced eulophid infestations, and its effect was more persistent than that of imidacloprid. Although application of kaolin might not be feasible on large forested areas, kaolin could represent a valuable control method in nurseries, where the repeated application with more toxic chemicals can result in high concentrations of residual pesticides in the soil.

Reduced oviposition by Diaprepes abbreviatus (Coleoptera: Curculionidae) and growth enhancement of citrus by Surround particle film

Regularly applied sprays of a particle film, Surround WP, greatly enhanced the growth of citrus trees on a poorly drained Winder soil at Fort Pierce, FL. After 3 yr of applications every 3 or 4 wk, Surround-treated trees had at least 5 times the mass, 6 times the canopy volume, and approximately 4 times the cross-sectional area of the tree stems at the graft union compared with untreated trees. The larger Surround-treated trees attracted a higher number of adult weevil Diaprepes abbreviatus (L.) and to a lesser extent citrus root weevil, Pachnaeus litus (Germar), per tree, but there was an equivalent number of egg masses per tree compared with the control trees. The number of egg masses per female weevil oviposited on Surround-treated trees was significantly less than either the control trees or trees treated biannually with an entomopathogenic nematode, BioVector. The number of larvae per tree recovered from the roots of excavated trees was greater from trees treated with Surround once every 3 wk compared with control trees. The data suggest that Surround particle film greatly enhanced the growth of citrus trees grown in a poorly drained soil. The reduction in oviposition by D. abbreviatus was insufficient to significantly reduce the number of root weevil larvae per tree feeding on the roots. However, the more vigorous trees resulting from Surround applications may be more resistant or tolerant to root weevil feeding.

Evaluation of hydrophobic and hydrophilic kaolin particle films for peach crop, arthropod and disease management

Hydrophobic and/or hydrophilic kaolin particle film treatments to peach (Prunus persica (L) Batsch) trees were evaluated for crop and pest management capabilities in six studies from 1997 to 2000. Unsprayed control and standard treatments, the latter consisting of a commercial pesticide program, were included for comparison. Treatments in initial studies were applied via handgun, which resulted in a uniform and heavy deposit of kaolin after the first application. In contrast, treatments in subsequent studies used airblast equipment, which provided a uniform but less dense coverage, even after multiple applications. Results showed that both formulations of kaolin provided control of oriental fruit moth (Grapholita molesta (Busck)), plum curculio (Conotrachelus nenuphar (Herbst)) and Japanese beetle (Popillia japonica Newman) that was comparable with or better than the standard pesticide program. Effective management of late season catfacing insects (tarnished plant bugs Lygus lineolaris (Palisot de Beauvois) and stinkbugs Acrosternum hilare (Say), Euschistus servus (Say), and E tristigmus (Say)) and leafrollers (undetermined species) was also observed, although kaolin applications significantly increased phytophagous mite (Panonychus ulmi (Koch)) levels. In contrast to arthropod management, kaolin failed to control either peach scab (Cladosporium carpophilum (Von Thumen)) or rusty spot (Podosphaera leucotricha (Ell and Ev) ES Salmon) in any of the 4 years of the study. However, hydrophobic kaolin provided effective brown rot (Monilinia fructicola (G Winter) Honey) control when applied via handgun, and partial control when applied via airblast; hydrophilic kaolin failed to provide any control. These results suggest that hydrophobicity and deposit density may be important factors for effective disease management. The application of kaolin significantly delayed fruit maturation, increased fruit size and increased soluble solids relative to the standard. This effect, attributed to a reduction in plant stress, also resulted in increased fruit number and yield on young trees, indicating that an accentuated beneficial response from kaolin applications may be possible.