Pest Management Science

Transgenic corn and cotton expressing Cry and Vip insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt), have been a valuable tool for the management of lepidopteran pests. In 2019, a Vip3Aa-resistant strain of Helicoverpa zea (CEW-Vip-RR) was isolated from F2 screens of field populations in Texas. Characterizing the resistance mechanism in this strain is important for predicting the sustained efficacy of current commercial Bt traits and guiding the development of future transgenic traits. Resistance to insecticidal proteins in Bt traits is commonly associated with reduced toxin binding, with the exception of Vip3Aa resistance being associated to altered proteolytic processing in the insect host gut. Therefore, Vip3Aa protoxin processing was tested by incubation with midgut fluids from CEW-Vip-RR relative to a susceptible strain (CEW-SS). Finding no significant processing differences, alterations in Vip3Aa binding were tested by comparing binding of radiolabeled and biotinylated Vip3Aa toxin to midgut brush border membrane vesicles (BBMV) from CEW-Vip-RR and CEW-SS larvae. Specific Vip3Aa binding to CEW-Vip-RR BBMV in these experiments was consistently reduced when compared with CEW-SS BBMV. These results support that an altered Vip3Aa- receptor is associated with resistance in CEW-Vip-RR. Understanding this resistance mechanism could have important implications for resistance management decisions considering widespread Cry1 and Cry2 resistance in H. zea populations. IMPORTANCEHelicoverpa zea is a major crop pest in the United States that is managed with transgenic corn and cotton producing insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt). However, H. zea has evolved widespread resistance to the Cry proteins produced in Bt corn and cotton, leaving Vip3Aa as the only plant incorporated protectant in Bt crops consistently providing excellent control of H. zea. The benefits provided by Bt crops will be substantially reduced if widespread Vip3Aa resistance develops in H. zea field populations. Therefore, it is important to identify resistance alleles and mechanisms that contribute to Vip3Aa resistance to ensure that informed resistance management strategies are implemented. This study is the first report of reduced binding of Vip3Aa to midgut receptors associated with resistance.

Spodoptera frugiperda (fall armyworm) is a notorious pest that threatens maize production world-wide. Current control measures involve the use of chemical insecticides and transgenic maize expressing Bacillus thuringiensis (Bt) toxins. Although several additional transgenes have confirmed insecticidal activity in other plants, limited research has been conducted in maize, at least partially due to the technical difficulty of maize transformation. Here, we describe implementation of a sugarcane mosaic virus (SCMV) vector for rapidly testing the efficacy of transgenes for the control of S. frugiperda in maize. Four categories of proteins were tested using the SCMV vector: (i) maize defense signaling proteins: peptide elicitors (Pep1 and Pep3) and jasmonate acid conjugating enzymes (JAR1a and JAR1b); (ii) maize defensive proteins: the previously identified ribosome-inactivating protein (RIP2) and maize proteinase inhibitor (MPI), and two proteins with predicted but unconfirmed anti-insect activities, an antimicrobial peptide (AMP) and a lectin (JAC1); (iii) lectins from other plant species: Allium cepa agglutinin (ACA) and Galanthus nivalis agglutinin (GNA); and (iv) spider and scorpion toxins: peptides from Urodacus yaschenkoi (UyCT3 and UyCT5) and Hadronyche versuta (Hvt). In most cases, S. frugiperda larval growth on maize was reduced by transient SCMV-mediated overexpression of genes encoding these proteins. Additionally, experiments with some of the SCMV-expressed genes showed effectiveness against two aphid species, Rhopalosiphum maidis (corn leaf aphid) and Myzus persicae (green peach aphid). Together, these results demonstrate that SCMV vectors can be exploited as a rapid screening method for testing the efficacy and insecticidal activity of candidate genes in maize.

A critical component of integrated pest management is minimizing disruption of biological control by reducing use of pesticides with significant non-target effects on natural enemies. Insecticide non-target effects testing for natural enemies has become increasingly common, but research examining the non-target effects of herbicides on natural enemies is scarce and recommendations regarding herbicide selectivity are non-existent. We used meta-analysis to summarize laboratory bioassays testing non-target effects of herbicides on arthropod natural enemies and identify patterns in taxon susceptibility and active ingredient toxicity. Data was extracted from 103 papers representing 801 total observations. Herbicides increased natural enemy mortality and decreased longevity, reproduction, and predation. Mesostigmatan mites and hemipterans were the most sensitive to herbicides and spiders, neuropterans, and hymenopterans were the least sensitive. Mortality was higher in juvenile predators versus parasitoids, but did not differ between adults; parasitoid juveniles are likely better protected within the host. In terms of acute mortality, metribuzin, glufosinate, and oxyfluorfen were the most harmful herbicides. Only nicosulfuron, rimsulfuron, pendimethalin, phenmedipham, atrazine, and urea did not increase natural enemy mortality. The large effect size of glufosinate is particularly concerning, as it is the most likely replacement herbicide for glyphosate in many crops. Many active ingredients remain under-studied. Our analysis indicates that herbicides have a strong potential to disrupt biological control in cropping systems. Simple SummaryReducing the use of pesticides that harm natural enemies of crop pests is important to pest management. Currently, there is limited information on how herbicides might affect natural enemies. The researchers found that herbicides increased natural enemy mortality and reduced their longevity and efficacy as predators. Some potential glyphosate replacement herbicides were more harmful than glyphosate. There was little or no data available for many herbicides and beneficial insects, indicating that much more research is needed on this topic.

BackgroundFall armyworm, Spodoptera frugiperda (J.E. Smith) threatens staple crops across Africa. Integrating entomopathogenic fungi into Integrated Pest Management (IPM) offers a sustainable alternative to sole reliance on insecticides. This study quantified the pathogenicity of Purpureocillium lilacinum and Clonostachys rosea against S. frugiperda under controlled conditions. MethodsSecond-fifth instar larvae and eggs were exposed to 1x107, 1x108, and 1x109 conidia mL-1 of each fungus; sterile water served as control. Mortality was recorded over 3-9 days after treatment (DAT); feeding reduction was measured gravimetrically. Larval mortality was analyzed with GLMs/GLMMs (binomial-probit); feeding reduction by ANOVA/Tukey; LD50 and LT50 were estimated from dose-response models. ResultsMortality increased with dose and time, and decreased with larval stage. Peak larval mortality reached [~]44% for P. lilacinum and [~]49% for C. rosea at 1x109 conidia mL-1 by 9 DAT. Egg mortality was concentration--dependent (up to 82% and 88% for P. lilacinum and C. rosea, respectively, at 1x109 conidia mL-1). Feeding reduction reached 60-74% in early instars at the highest dose. Early instars were consistently more susceptible than late instars. Model outputs indicated significant effects of concentration and time; interaction concentrationxtime was significant, whereas fungal speciesxconcentration was not. Our findings supported the initial hypothesis. Mortality and feeding reduction increased with higher fungal concentrations and longer exposure times, and younger instars were consistently more susceptible than older instars. While both P. lilacinum and C. rosea were pathogenic, differences between species were minor compared to the effects of dose and instar stage. These outcomes validated the formulated hypotheses, and reinforce the potential of these native fungi as candidates for IPM. ConclusionsNative P. lilacinum and C. rosea display dose--, stage--, and time--dependent pathogenicity and feeding suppression against S. frugiperda. These species are promising candidates for IPM; field validation and formulation optimization are the next steps.

Decreased sensitivity to fungicides impacts the effectiveness of fungicide applications for managing plant disease. Knowledge of the frequency of decreased sensitivity in field populations is critical for evaluating risks for disease control. This study has applied a droplet digital PCR detection approach to assess pathogen populations and quantify the frequencies of alleles associated with decreased sensitivity to either demethylation inhibitor or succinate dehydrogenase inhibitor fungicides in Pyrenophora teres causing net blotch on barley in Western Australia. Pyrenophora teres f. maculata was the most frequent form of the pathogen in the sampled region. Frequencies of decreased fungicide sensitivity alleles varied, being as great as 92% for the PtTi insertion in the CYP51A promoter, 88% for C-S75 and 28% for L489-2. Impacts of cultivar selection and weed hosts on the presence and survival of decreased fungicide sensitivity were observed. Determining the dynamics of alleles within different field populations of P. teres provides an important perspective on the impact of fungicides, the fitness associated with decreased fungicide sensitivity alleles and the susceptibility of barley cultivars.

Tetranychus urticae (Koch) is an economically important pest of many agricultural commodities in the Pacific Northwest. Multiple miticides are currently registered for control including abamectin, bifenazate, bifenthrin, and extoxazole. However, populations of Tetranychus urticae have developed miticide resistance through multiple mechanisms, in many different growing regions. Producers of agricultural commodities where Tetranychus urticae infestations are problematic rely on integrated pest management tools to determine optimal control methods. Within this species multiple single nucleotide polymorphisms have been documented in different genes which are associated with miticide resistance phenotypes. The detection of these mutations through TaqMan qPCR has been suggested as a practical, quick, and reliable tool to inform agricultural producers of miticide resistance phenotypes present within their fields and have potential utility for making appropriate miticide application and integrated pest management decisions. Within this investigation we examined the use of a TaqMan qPCR-based approach to determine miticide resistance genotypes in field-collected populations of Tetranychus urticae from mint fields and hop yards in the Pacific Northwest of the United States and confirmed the results with a multiplex targeted sequencing. The results suggest the TaqMan approach accurately genotypes Tetranychus urticae populations collected from agricultural fields. The interpretation of the results, however, provide additional challenges for integrated pest management practitioners, including making miticide application recommendations where populations of Tetranychus urticae are a mix of resistant and wildtype individuals.

The Sterile Insect Technique (SIT) is an eco-friendly control method that may prove effective against Bagrada hilaris, a pest native to India, Southeast Asia, and Middle and central Africa and reported as invasive in the southwestern USA, Hawaii, Mexico, South America, and two Mediterranean islands. This insect causes significant crop damage due to its intense feeding behavior and is currently managed almost exclusively with synthetic insecticides. In this context, SIT offers a promising alternative for controlling B. hilaris populations, provided that sufficient numbers of sterile males are continuously released. Based on this premise, we conducted a preliminary laboratory study to evaluate the overflooding ratio (OFR)--the proportion of non-irradiated to irradiated males required to suppress the populations fertility. We tested various OFRs (1:1, 1:2, 1:5, and 1:10), monitoring both the number of eggs laid and hatching rates. Our results show a significant decrease in fertility as the percentage of irradiated males increases. Among the ratios examined, 1:5 emerged as the most advantageous in terms of both reducing fertility and ease of application. Although further validation under field conditions is needed, our findings suggest that SIT could effectively contribute to an integrated management strategy for B. hilaris, reducing the reliance on chemical pesticides and supporting a more sustainable approach.

The red palm weevil (Rhynchophorus ferrugineus; RPW) is an important pest threatening date palm cultivation worldwide. Conventional insecticide-based management is limited by environmental concerns and the development of resistance in RPW populations. Entomopathogenic fungi (EPF), such as Beauveria bassiana, offer a promising biocontrol alternative. While laboratory and semifield studies have demonstrated their potential as insecticides, evidence from field-scale applications under diverse environmental conditions remains scarce. This study evaluated the seasonal efficacy and persistence of B. bassiana as a preventive treatment against RPW in male and female date palm groves subjected to different cultivation practices in Israels Arava region. Healthy palms were equipped with IoTree sensors to monitor RPW infestation dynamics. EPF treatments were applied at the start of each season, and control trees were left untreated. Soil samples were collected seasonally to quantify fungal colony-forming units (CFUs) and assess their association with treatment outcomes. Results demonstrated a significant seasonal influence on EPF efficacy, with autumn treatments yielding the highest reduction in infestation rates, and summer applications showing limited effectiveness. Efficacy also varied between grove types: spring applications were most effective in male groves, whereas autumn treatments were superior in female groves. A positive correlation was found between B. bassiana CFUs in the soil and palm health, indicating that EPF persistence enhances treatment success. These findings highlight the importance of seasonal and site-specific optimization of EPF-based biocontrol strategies. Further research is needed to refine application schedules and validate outcomes across larger-scale trials.

The spittlebug Philaenus spumarius (Hemiptera: Aphrophoridae) is the predominant vector of Xylella fastidiosa (Xanthomonadales: Xanthomonadaceae) in Apulia and Europe. Current control strategies of the insect vector rely on mechanical management of nymphal stages and insecticide application against adult populations. Entomopathogenic fungi (EPF) are biological control agents naturally attacking spittlebugs and may effectively reduce population levels of host species. Different experimental trials in controlled conditions have been performed to i) identify naturally occurring EPF on P. spumarius in Northwestern Italy, and ii) evaluate the potential for biocontrol of the isolated strains on both nymphal and adult stages of the spittlebug. Four EPF species were isolated from dead P. spumarius cadavers collected in semi-field conditions: Beauveria bassiana, Conidiobolus coronatus, Fusarium equiseti and Lecanicillium aphanocladii. All the fungal isolates showed entomopathogenic potential against nymphal stages of P. spumarius ({approx} 45 % mortality), except for F. equiseti, in preliminary trials. No induced mortality was observed on the adult stage. Lecanicillium aphanocladii was the most promising fungus and its pathogenicity against spittlebug nymphs was further tested in different formulations (conidia vs blastospores) and with natural adjuvants. Blastospore formulation was the most effective in killing nymphal instars and reducing the emergence rate of P. spumarius adults, reaching mortality levels (90%) similar to those of the commercial product Naturalis(R), while no or adverse effect of natural adjuvants was recorded. The encouraging results of this study pave the way for testing EPF isolates against P. spumarius in field conditions and find new environmentally friendly control strategies against insect vectors of X. fastidiosa.

Myzus persicae, a serious sap-sucking pest of a large variety of host plants in agriculture, is traditionally controlled using chemical insecticides but there is interest in using biopesticides as restrictions are increasingly placed on the use of broad-spectrum pesticides. Here we show that in petri dish experiments high concentrations of the fungal entomopathogen Beauveria bassiana (strain PRRI 5336) lead to rapid mortality of M. persicae but at a low concentration (1 x 104 conidia mL-1) there is a hormetic effect where longevity and fecundity are enhanced. Hormetic effects persisted across a generation with reduced development times and increased fecundity in the offspring of M. persicae exposed to B. bassiana. Whole plant experiments point to a hormetic effect being detected in two out of three tested lines. The impact of these effects might also depend on whether M. persicae was transinfected with the endosymbiont Rickettsiella viridis, which decreases fecundity and survival compared to aphids lacking this endosymbiont. This fecundity cost was ameliorated in the generation following exposure to the entomopathogen. While B. bassiana is effective in controlling M. persicae especially at higher spore concentrations, utilization of this entomopathogen requires careful consideration of hormetic effects at lower spore concentrations, and further research to optimize its application for sustainable agriculture is recommended. AUTHOR SUMMARYBiopesticides such as Beauveria bassiana can be effective alternatives to chemical insecticides to control insect pests. We tested the efficacy of this biopesticide against the important agricultural pest aphid Myzus persicae in laboratory experiments. We also tested whether the potential biological control agent and endosymbiont Rickettsiella viridis could provide protection against mortality caused by B. bassiana. While high doses of B. bassiana caused rapid mortality in aphids, low doses enhanced aphid fecundity and survival. This enhancement persisted into the next generation, with shortened development times and increased fecundity regardless, even when high doses were used in the previous generation. The endosymbiont R. viridis did not provide clear protection against B. bassiana, in contrast to previous studies in other aphid species, but beneficial effects at low doses also occurred in this aphid line. We also observed hormesis on experiments on whole plants, but only for some aphid genotypes. To a lesser extent, we also observed beneficial effects of low doses of B. bassiana in experiments on whole plants, but only in some aphid genotypes. Fitness enhancement by biopesticides at low doses raises concerns for field applications but further research is required to understand its underlying mechanisms.

BACKGROUNDOne of the proposed applications of gene drives has been to revert pesticide resistant mutations back to the ancestral susceptible state. Insecticides that have become ineffective because of the rise of resistance could have reinvigorated utility and be used to suppress pest populations again, perhaps at lower application doses. RESULTSWe have created a laboratory model for susceptibility gene drives that replaces field-selected resistant variants of the acetylcholine esterase (Ace) locus of Drosophila melanogaster with ancestral susceptible variants. We constructed a CRISPR/Cas9 homing drive and found that homing occurred in many genetic backgrounds with varying efficiencies. While the drive itself could not be homozygosed, it converted resistant alleles into susceptible ones and produced recessive lethal alleles that could suppress populations. Our studies provided evidence for two distinct classes of Gene Drive Resistance (GDR): rather than being mediated by the conventional Non-Homologous End-joining (NHEJ) pathway, one seemed to involve short homologous repair and the other was defined by genetic background. Additionally, we used simulations to explore a distinct application of susceptibility drives; the use of chemicals to prevent the spread of synthetic gene drives into protected areas. CONCLUSIONSInsecticide susceptibility gene drives could be useful tools to control pest insects however problems associated with particularities of the target loci and GDR will need to be overcome for them to be effective. Furthermore, realistic patterns of pest dispersal and high insecticide exposure rates would be required if susceptibility were to be useful as a safety-switch to prevent the unwanted spread of gene drives.

Predatory mites biologically control a range of arthropod crop pests and are often central to agricultural IPM strategies globally. Conflict between chemical and biological pest control has prompted increasing interest in selective pesticides with fewer off-target impacts on beneficial invertebrates, including predatory mites. However, the range of predatory mite species included in standardised pesticide toxicity assessments does not match the diversity of naturally-occurring species contributing to biocontrol, with most testing carried out on species from the family Phytoseiidae. Here, we aim to bridge this knowledge gap by investigating the impacts of 22 agricultural pesticides on the predatory snout mite Odontoscirus lapidaria (Kramer) (family Bdellidae). Using internationally standardised testing methodologies, we identified several active ingredients with minimal impact on O. lapidaria mortality, including Bacillus thuringiensis, nuclear polyhedrosis virus, flonicamid, afidopyropen, chlorantraniliprole and cyantraniliprole, which may therefore be good candidates for IPM strategies utilising both chemical and biological control. Importantly, we reveal differences between Bdellidae and Phytoseiidae in responses to a number of chemicals, including the miticides diafenthiuron and abamectin, highlighting the risk of making generalisations around acute toxicity based on tests with one beneficial mite family. We also explored the impacts of several pesticides on a second Bdellidae species and found differences in the response to chlorpyrifos compared with O. lapidaria, further highlighting the taxon-specific nature of non-target toxicity effects.

Recently, resistance to diamide insecticides (IRAC group 28) has been reported in various lepidopteran pests, including Spodoptera exigua. In the present study, susceptibility of six field populations was evaluated to two diamide insecticides: chlorantraniliprole and flubendiamide. The bioassay test for resistance revealed a high level of diamide resistance and helped to select a diamide resistant (Di-R) strain, whose LC50 values against chlorantraniliprole and flubendiamide were 28,950- and 135,286-fold higher, respectively, than those of susceptible strains. In the ryanodine receptor, instead of the G4946E mutation, one of the well-known diamide resistance mechanisms, we found a I4790M mutation and identified the resistance allele-specific indel linked to it. Resistance allele diagnostic primers were designed using this distinct region and applied in loop-mediated isothermal amplification (LAMP) and general PCR. LAMP accurately detected the specific indel when conducted for 2 h at temperature range from 63 {degrees}C to 65 {degrees}C and using four LAMP primers; its efficiency was further amplified by an additional loop primer. A broad range of DNA concentrations was workable in the LAMP assay, with the minimum detectable DNA concentration of 100 pg. The new DNA releasing method used for the LAMP assay consisted of 5 min of incubation of a larva or adult tissue at 95{degrees}C. The entire diagnostic process, which included the DNA releasing technique and LAMP, lasted only 100 min. This simple and accurate LAMP assay can be applied to monitor diamide resistance and for integrated resistance management of S. exigua in the field.

BACKGROUNDThe insecticidal proteins derived from Bacillus thuringiensis Berliner (Bt) have been effectively employed in controlling lepidopteran pests, notably in transgenic crops targeting Spodoptera species. However, concerns have arisen regarding the long-term efficacy due to the emergence of tolerant and resistant insect populations. Prior research suggested that repeated exposures to Bt may contribute tolerance, but the specific effects of sequential exposure to purified Cry1 proteins remain unclear. This study aimed to assess whether prior exposure of Spodoptera exigua (Huber, 1808) neonate larvae to sublethal concentrations of Cry1Ab and Cry1Ca proteins would heighten their tolerance upon subsequent exposure, and whether such effects would extend to their offspring. RESULTSPre-exposure to Cry1Ab did not affect larval responses to the toxin. For Cry1Ca, a slight increase was observed under one treatment condition, but the effect was not considered biologically relevant in practical terms. Similarly, transgenerational analysis revealed no enhancement of tolerance; rather, there was a negative impact on the offsprings response in some cases. CONCLUSIONThese findings indicate that although previous studies have documented that sublethal contact with bacterial preparations may significantly affect the insect tolerance, exposure to purified Cry proteins is unlikely to lead to the development of tolerance in S. exigua. Therefore, our findings suggest that sublethal exposure to these Cry1 proteins may not significantly affect the long-term efficacy of Bt-based pest management strategies relaying on them.

Many lepidopterans species, such as fruit borer (Helicoverpa armigera) on tomato, apple moth Cydia pomonella (codling moth), and orange moth Thaumatotibia leucotreta (false codling moth), are among many lepidopterans that are crop pests. In the early 1930s, the concept of the sterile insect technique was conceived in response to the global threat of insect pests and the excessive use of insecticides, which were proven to pose a health risk to humans. This pest control tactic has gained and is currently gaining more traction in all regions where it is implemented on both small and large scales. This systematic review looks at the recent research advances in the application of sterile insect techniques for the control of lepidopteran pests. The paper analyses publications, focusing on the geographic distribution of studies, target species, irradiation source, and the year of publication. It highlights the growing interest in SIT as an environmentally friendly pest management strategy compared to insecticide use. The paper compiles and summarises information over the last two decades on the lepidopteran species studied, the study approach, the country where the study was performed, the source of irradiation, and the year of publication. It also analysed the suitability of each lepidopteran species as an SIT candidate and the effectiveness of this control strategy. The review resulted in 2 537, from which 24 publications matched the search criteria. From the results, 14 species were identified, and the most studied lepidopteran was T. leucotreta. The review discusses the effectiveness of SIT in controlling various lepidopteran species and explores the potential for further development and implementation of SIT programmes globally.

BACKGROUNDInsect pests present a global threat to crops, with plant resistance representing a key breeding goal. The cabbage stem flea beetle (Psylliodes chrysocephala; CSFB) is the most damaging pest of oilseed rape (Brassica napus; OSR) within Europe; however, CSFB resistance is yet to be found within B. napus. To address this, we examine CSFB larval development over time, explore antibiosis across a diverse Brassica panel, and test whether larvae can develop within model Brassica relatives (Brassica rapa and Arabidopsis thaliana). RESULTSCSFB larvae completed development from four weeks post-infestation, undergoing a 20-fold size increase, with larval recovery after two weeks allowing semi-high throughput resistance phenotyping. Applying this method to 98 Brassica genotypes (97 B. napus and a single Sinapis alba), we found weak evidence for genotype effects on larval survival, however phenotype validation with resistant and susceptible B. napus genotypes showed no differences in larval survival or adult emergence. Larval antibiosis was consistently observed in S. alba. Finally, we showed that B. rapa and A. thaliana represent suitable hosts for CSFB, with larvae increasing 8-10x in size after two weeks. CONCLUSIONCSFB larval antibiosis appears absent within B. napus, possibly due to bottlenecks experienced during domestication. However, larval antibiosis is present within S. alba, and future work should study the basis of this resistance. Further, CSFB larval screening in Brassica relatives presents an opportunity to explore CSFB resistance genetics, informing breeding progress for insect resistance in B. napus.

The spotted wing drosophila (SWD) Drosophila suzukii (Diptera: Drosophilidae) is a pest of soft fruit. Since its introduction in Europe in 2008 farmers struggle to protect their crops. The sterile insect technique (SIT) has proven efficient at controlling numerous fruit fly species and could be deployed to control D. suzukii. In recent years, key elements of SIT applied to D. suzukii have become available. However, field- and field-like experiments are scarce. In this experiment, we assayed the efficacy of a high-performance strain at reducing the reproduction of D. suzukii in complex, yet replicated and controlled conditions. Two ratios of sterile to fertile insects (5:1 and 1:1) using bisexual releases were compared to a control treatment with fertile, wild flies only. The presence of sterile individuals at a 5:1 ratio significantly reduced fly reproduction, measured after 5 days, by an approximate threefold factor. However, the proportion of infested fruits in the treated plots remained unaffected. The number of available berries in the cage appeared an unexpected determinant of fly infestation, suggesting undocumented density-dependent processes. The success of this assay opens the door to larger scales experiments, over several generations, and, in the near future, the field-evaluation of the efficacy of the SIT to control D. suzukii.

The field performance of Sterile Insect Technique (SIT) is improved by sex-sorting and releasing only the sterile males. This can be accomplished by resource-intensive separation of males from females by morphology. Alternatively, sex-ratio biasing genetic constructs can be used to selectively kill one sex without the need for manual or automated sorting, but the resulting genetically engineered (GE) control agents would be subject to additional governmental regulation. Here we describe and demonstrate a method for the batch production of non-GE males that is applicable for sex-selective production of males suitable for genetic biocontrol programs. This method could be applied to generate the heterogametic sex (XY, or WZ) in any organism with chromosomal sex determination. We observed up to 100% sex-selection with batch cultures of more than 103 individuals. Using a stringent transgene detection assay, we demonstrate the potential of mass rearing of transgene free males.

The important damages caused by Dactylopius opuntiae (Hemiptera: Dactylopiidae) to cactus crops around the world require an integrated pest management (IPM) approach, based on the combination of several techniques (varietal resistance, biological, chemical methods, etc). In this sense, this study evaluated the resistance of 10 Moroccan cactus genotypes to D. opuntiae in order to characterize the expression of antixenosis and/or antibiosis. Antixenosis was accessed in the greenhouse and in the laboratory (26{+/-} 2{degrees}C) using choice and non-choice tests with 1st instar nymphs. Aakria and Cherratia showed a strong antixenosis effect towards D. opuntiae (0-0.3 D. opuntiae alive 30 after infestation). For antibiosis assessment, 30 1st instar nymphs were confined on cladodes of the 10 selected genotypes under the same laboratory conditions to allow their development, as well as the life cycle performance and behavior of D. opuntiae on the 10 selected cactus genotypes, were evaluated under greenhouse conditions. No influence of genotypes on insect oviposition was observed, indicating that the mealybug does not prefer any genotypes over the others for oviposition. The mealybug failed to develop on genotypes Aakria and Cherratia and did not grow beyond the young female stage on all other resistant genotypes tested. Similarly, first instar nymphs fed on genotypes Marjana, Melk Zhar, and A200 died without reaching the second instar nymph stage. In addition, all genotypes tested had a negative effect on nymph viability (<24%), indicating resistance (antibiosis and/or antixenosis) to the cactus scale. These cactus genotypes may all be useful in breeding programs focused on cactus resistance to mealybugs.

BACKGROUNDTetranychus cinnabarinus is one of the pest insects most severely influencing strawberry production. It has a high attack rate and causes severe economic losses. Laboratory toxicity tests and greenhouse experiments were carried out using 13 acaricides to determine their efficacy and potential mechanisms of action.\n\nRESULTSAbamectin showed the highest efficacy against T. cinnabarinus female mites; its LC50 value was 0.18mg L-1. Pyridaben, cyhalothrin, veratrine, and carbosulfan showed reasonably high efficacy; their LC50 values were 2.69 mg L-1, 3.94 mg L-1, 5.98 mg L-1, and 6.75 mg L-1, respectively. Less effective were hexythiazox and bifenthrin, their LC50 values were 9.82 mg L-1 and 19.09 mg L-1, respectively. Other acaricides such as spirodiclofen, chlorantraniliprole, chlorfenapyr, spinosad, and bifenazate did not show good efficacy. The status of female mites treated with avermectin, pyridaben, kanghebio and cyhalothrin changed significantly under a fluorescence microscope. There were no significant differences among female mites treated with spirotetramat, chlorantraniliprole, spinosad and bifenazate. Enzyme activity tests showed that Kanghebio and cyhalothrin obviously inhibited Ca2+-adenosine triphosphatase (Ca2+-ATPase), while veratrine and kanghebi obviously inhibited acetylcholinesterase (TChE) and monoamine oxidase (MAO). Cyhalothrinexerted an auxo-action on MAO. Greenhouse experiment indicated that abamectin showed the best efficacy, as well as the longest duration of efficacy, pyridaben, cyhalothrin, veratrine, and kanghebio followed, while carbosulfan, hexythiazox, and bifenthrin performed the worst.\n\nCONCLUSIONSOur study provided a scientific basis for chemical pesticides to be replaced by these and potentially other new bio-pesticides.