Major Crop Pests Research Articles

The Spodoptera frugiperda Host Strains: What They Are and Why They Matter for Understanding and Controlling This Global Agricultural Pest.

Fall armyworm (Spodoptera frugiperda [J.E. Smith]) is a moth native to the Western Hemisphere where it is a major pest of corn (maize) and multiple other crops. It is now a global threat with its recent discovery and dissemination in the Eastern Hemisphere. Its broad host range is in part due to two subpopulations denoted as 'host strains' that differ in host plant specificity. Therefore, identifying the strains present in a location is critical to assessing what crops are at risk of infestation. However, much remains uncertain about how the strains differ and even on the fundamental issue of how they are identified. Complicating factors include the host strains are morphologically indistinguishable, the defining behavior of the strains (host plant specificity) is variable, and the existence of significant differences between geographical populations and laboratory colonies that are independent of strain identity. These factors contribute to substantial disagreements in the literature on presumptive strain differences. This paper presents a summary of strain characteristics and suggests the criteria that should be met before concluding a trait is 'strain-specific'. The intent is to facilitate a common understanding of what the strains represent and to develop a more consistent experimental framework for studies on strain phenotypes. Evidence is summarized that supports a primary role for Z-linked genes in strain identity, which has potential implications for genetic approaches to define the strains, and we discuss the possibility that the strains arose from allopatric (rather than sympatric) speciation processes.

The clock gene, period, influences migratory flight and reproduction of the oriental armyworm, Mythimna separata(Walker).

The oriental armyworm, Mythimna separata, is a major long-distance migratory insect pest of grain crops in China and other Asian countries. Migratory flights and reproductive behavior usually occur at night, regulated by a circadian rhythm. However, knowledge about the linkages between adult flight, reproduction, and clock genes is still incomplete. To fill this important gap in our knowledge, a clock gene (designated Msper) was identified and phylogenetic analysis indicated that the encoded protein (MsPER) was highly similar to PER proteins from other insect species. Quantitative RT-PCR assays demonstrated that significantly different spatiotemporal and circadian rhythmic accumulations of mRNA encoding MsPER occurred during development under steady 14h:10h light:dark conditions. The highest mRNA accumulation occurred in adult antennae and the lowest in larvae. Msper was expressed rhythmically in adult antennae, relatively less in photophase and more entering scotophase. Injecting small interference RNA (siRNA) into adult heads effectively knocked down Msper mRNA levels within 72h. Most siRNA-injected adults reduced their evening flight activity significantly and did not exhibit a normal evening peak of flight activity. They also failed to mate and lay eggs within 72h. Adult mating behavior was restored to control levels by 72h post injection. We infer that Msper is a prominent clock gene that acts in regulating adult migratory flight and mating behaviors of M.separata. Because of its influence on migration and mating, Msper may be a valuable gene to target for effective management of this migratory insect.

Enhancing the Expression of the OsF3H Gene in Oryza sativa Leads to the Regulation of Multiple Biosynthetic Pathways and Transcriptomic Changes That Influence Insect Resistance.

The white-backed planthopper (WBPH) is a major pest of rice crops and causes severe loss of yield. We previously developed the WBPH-resistant rice cultivar "OxF3H" by overexpressing the OsF3H gene. Although there was a higher accumulation of the flavonoids kaempferol (Kr) and quercetin (Qu) as well as salicylic acid (SA) in OxF3H transgenic (OsF3H or Trans) plants compared to the wild type (WT), it is still unclear how OsF3H overexpression affects these WBPH resistant-related changes in gene expression in OxF3H plants. In this study, we analyze RNA-seq data from OxF3H and WT at several points (0 h, 3 h, 12 h, and 24 h) after WBPH infection to explain how overall changes in gene expression happen in these two cultivars. RT-qPCR further validated a number of the genes. Results revealed that the highest number of DEGs (4735) between the two genotypes was detected after 24 h of infection. Interestingly, it was found that several of the DEGs between the WT and OsF3H under control conditions were also differentially expressed in OsF3H in response to WBPH infestation. These results indicate that significant differences in gene expression between the "OxF3H" and "WT" exist as the infection time increases. Many of these DEGs were related to oxidoreductase activity, response to stress, salicylic acid biosynthesis, metabolic process, defense response to pathogen, cellular response to toxic substance, and regulation of hormone levels. Moreover, genes involved in salicylic acid (SA) and ethylene (Et) biosynthesis were upregulated in OxF3H plants, while jasmonic acid (JA), brassinosteroid (Br), and abscisic acid (ABA) signaling pathways were found downregulated in OxF3H plants during WBPH infestation. Interestingly, many DEGs related to pathogenesis, such as OsPR1, OsPR1b, OsNPR1, OsNPR3, and OsNPR5, were found to be significantly upregulated in OxF3H plants. Additionally, genes related to the MAPKs pathway and about 30 WRKY genes involved in different pathways were upregulated in OxF3H plants after WBPH infestation. This suggests that overexpression of the OxF3H gene leads to multiple transcriptomic changes and impacts plant hormones and pathogenic-related and secondary-metabolites-related genes, enhancing the plant's resistance to WBPH infestation.

Non-consumptive effects of predation risk on prey population regulations: empirical evidence from the invasive spider mite Tetranychus ludeni

Tetranychus ludeni Zacher is an invasive pest from Europe. It infests more than 300 plant species, including many economically important crops such as bean Phaseolus vulgaris L. (Fabales: Fabaceae), eggplant Solanum melongena L. (Solanales: Solanaceae), and many other cucurbitaceous plants. Gotoh et al. (2015) predict that this species could replace T. urticae to become a major crop pest in the world. It is often assumed that the success of biological control using predators is achieved through direct predation. However, it is still largely unknown whether predation risk could contribute to the effectiveness of prey biological control. In the present study we investigated the effects of cues from the predatory mite Phytoseiulus persimilis and killed T. ludeni on life history traits and offspring fitness of T. ludeni, providing novel knowledge for evaluation of the non-consumptive contribution to the biological control of T. ludeni and for future development of new spider mite control methods using these cues. We demonstrated that the cues from the predators and killed prey shortened the longevity by more than 23% and oviposition period by more than 35% and reduced the number of eggs laid by more than 31% in T. ludeni females. These cues also significantly reduced the intrinsic rate of increase and net population growth rate and prolonged the time to double the population size. Furthermore, in response to predator cues females significantly delayed their lifetime production of daughters and laid significantly smaller eggs. Offspring from predator-exposed mothers developed significantly more slowly. Our findings strongly suggest that the non-consumptive mortality caused by cues from both predators and killed prey can significantly reduce prey fitness, suppressing their population and lowering their damage to crops. The earlier prey death caused by these cues could result from the energic costs of natural enemy avoidance (Luong et al. 2017), decrease of foraging rate or food intake (Hermann & Thaler 2014) and increase of oxidative damage (Janssens & Stoks 2013). The present study partially supports previous reports that non-consumptive impacts of predation risk on prey are transgenerational (Tariel et al. 2020). Our study provides critical information for evaluation of biological control effectiveness using predators and paves the way for identification of chemical odors from the predator and killed prey and development of new materials and methods for the control of spider mite pests.

Facultative symbionts are potential agents of symbiont-mediated RNAi in aphids.

Aphids are major crop pests, and they can be controlled through the application of the promising RNA interference (RNAi) techniques. However, chemical synthesis yield of dsRNA for RNAi is low and costly. Another sustainable aphid pest control strategy takes advantage of symbiont-mediated RNAi (SMR), which can generate dsRNA by engineered microbes. Aphid host the obligate endosymbiont Buchnera aphidicola and various facultative symbionts that not only have a wide host range but are also vertically and horizontally transmitted. Thus, we described the potential of facultative symbionts in aphid pest control by SMR. We summarized the community and host range of these facultative symbionts, and then reviewed their probable horizontal transmitted routes and ecological functions. Moreover, recent advances in the cultivation and genetic engineering of aphid facultative symbionts were discussed. In addition, current legislation of dsRNA-based pest control strategies and their safety assessments were reviewed.

Seasonal Population of Drosophila suzukii (Diptera: Drosophilidae) and Pesticide Use Pattern after Its Invasion in Caneberry Crops in Pennsylvania (USA)

Drosophila suzukii (Diptera: Drosophilidae) is a major invasive pest of caneberries (e.g., blackberries and raspberries) and other thin-skinned fruit crops. In recent years, it has been reported as an economically important fruit pest in many countries. In caneberries, the timely detection and management of invasive insect pests such as D. suzukii is important to maintain profitability and avoid fruit export restriction. Invasions by such new pest species in commercial crop production often changes pesticide use patterns and frequency as growers try to control pest populations on their farms. In this study, we examined the seasonal population of D. suzukii and pesticide use patterns before and after D. suzukii invasion in primocane-fruiting raspberry and floricane-fruiting blackberry crop production in Pennsylvania. The results of seasonal monitoring conducted over two years showed higher populations of D. suzukii fruit flies during the settle period. The evaluation of crop-specific pesticide programs showed an increase in pesticide use frequency compared to the crop season before D. suzukii invasion in the blackberry planting. Similarly, over a five-fold increase in pesticide application was recorded in the raspberry planting in the year following invasion. The implications of increased pesticide use patterns in blackberry and raspberry production are discussed.

Susceptibilities of Helicoverpa zea (Lepidoptera: Noctuidae) Populations From the Mississippi Delta to a Diamide Insecticide.

The corn earworm, Helicoverpa zea (Boddie), is a major pest of row crops in the Southern United States. Control of this insect is dependent on preventative insecticidal transgenic crops and synthetic insecticide applications when damaging populations are encountered in the field. Recently, the use of chemicals from the diamide class of insecticides, particularly chlorantraniliprole, has been used to control unacceptable populations. Due to the increased importance of this active ingredient for control of corn earworms, populations of this insect from the Mississippi Delta have been monitored for susceptibilities annually since 2016. Overall, 58 populations of H. zea were examined for their susceptibility to chlorantraniliprole through diet-incorporated bioassays from 2016 to 2021. Based on probit analysis, there was only a 4-fold difference between the highest and lowest LC50 estimates for all populations tested. Through weights of 2nd and 3rd instar larvae, there appears to be a substantial fitness cost associated with surviving caterpillars that fed on various concentrations of chlorantraniliprole in bioassays, which is not captured through the yes or no response of typical survival analysis. Overall, there was not a detectable trend of reduced susceptibility to chlorantraniliprole over the course of the six-year study.

Synergistic Effects of Graphene Oxide and Pesticides on Fall Armyworm, Spodoptera frugiperda.

Fall armyworm Spodoptera frugiperda, a native insect pest in tropical and subtropical America, has rapidly spread to most parts of China and become a major pest of corn and other crops since invading in early January 2019. As an emergency and important control measure, chemical control of S. frugiperda has the advantages of quick effect and low cost. However, long-term and large-scale use of pesticides might pollute the environment and increase pest resistance. By improving the control effect and reducing the dosage of chemical pesticides, graphene oxide (GO) is used synergistically with insecticides to increase control efficacy to achieve low-cost and sustainable management of insect pests as a new type of synergist. In this study, graphene oxide was compounded with insecticides to form nanocomposites. To clarify pest physiological responses, the laboratory toxicity of graphene oxide-insecticide nanocomposites was measured on the larvae of S. frugiperda. The results demonstrated that GO could enhance the activity of four selected pesticides: chlorantraniliprole (Chl), beta cypermethrin (Bet), methoxyhydrazide (Met) and spinetoram (Spi). Compared with pesticides alone, the toxicity of Chl-GO, Bet-GO, Met-GO and Spi-GO mixtures to the third instar larvae of S. frugiperda increased by 1.56, 1.54, 2.53 and 1.74 times, respectively. The easy preparation and higher bioactivity of GO-pesticide nanocomposites indicated their promising application potential in pest control.

Flubendiamide Resistance and Its Mode of Inheritance in Tomato Pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

Tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is the major pest of tomato crops in Pakistan. Insecticides are commonly used for the management of this insect-pest. To develop a better insecticide resistance management strategy and evaluate the risk of resistance evolution, a field collected population of the tomato pinworm was selected with flubendiamide in the laboratory. We investigated the genetics of flubendiamide resistance and concentration-mortality response to other insecticides by selecting a field strain of tomato pinworm with commercial flubendiamide formulation. Tuta absoluta was reciprocally crossed with resistant strain (Fluben-R) and was selected up to 13 generations, while F1 progeny was back-crossed with resistant parent (Fluben-R). The results of LC50 and Resistance Ratio (RR) demonstrated a higher resistance developed in field and laboratory-selected strains (G2 and G13, respectively). Field-collected and laboratory-selected (Fluben-R) strains demonstrated higher intensity of concentration-mortality response against chlorantraniliprole, thiamethoxam, permethrin, abamectin and tebufenozide compared to susceptible ones. Based on the overlapping of 95% FL, it demonstrated significant differences, revealing that it was not sex linked (autosomal) with no maternal effects. The backcross analysis of the F1´ resistant parent resulting in significant differences at all concentrations suggests that resistance is controlled by more than one factor; the null hypothesis was rejected and inheritance was under polygenic control. Resistance progression from 38 to 550 folds demonstrated that T. absoluta can develop a higher level of resistance to flubendiamide. Concentration-mortality response experiments demonstrated that the LC50 of some tested insecticides was higher for field-collected and laboratory-selected strains, suggesting that resistance mechanisms should be studied at a molecular level for better understanding. These results could be helpful to design resistance management strategies against the tomato pinworm.

A Synthetic Blend of Fruit and Live Yeast Odours Shows Promise for Trapping Mated Female Queensland Fruit Fly, Bactrocera tryoni, in the Field.

Tephritid fruit flies are major horticultural pests of fruit and vegetable crops. Developing an odour lure that can attract mated female flies under field conditions has presented a major challenge to chemical ecologists around the globe. We have designed a new lure to attract female Queensland fruit fly, Bactrocera tryoni, based on the knowledge that this pest tephritid is attracted not only to odours from ripening fruits, but also to odours of symbiotic (gut-associated) yeasts on which the larvae feed. Initial field trials screened four volatile mixtures, each containing a base mix of three, short-chain "fruit ripening" esters and differing in the addition of long-chain "fruity" esters and / or alcohols produced by live yeasts. Results demonstrated that the lure formulated from short-chain esters and live yeast alcohols attracted the most female flies, with significantly higher catches than an odourless control trap, and a protein-baited trap. As electrophysiological studies exploring peripheral responses in tephritids to alcohols associated with fermentation have not been extensively investigated, we conducted this work on both the antennae and maxillary palps, and discovered that three yeast alcohols were detected by both sensory organs. Performance trials conducted in pome fruit and stone fruit orchards evaluated the six-component blend of short-chain ester and live yeast alcohol lure against a commercially available synthetic fruit-odour lure and a protein-based lure. In the apple orchard, the new lure caught significantly more female flies, and in particular mated females, compared to the commercially available lures. In the stone fruit orchard, while the new lure again caught the most mated female flies compared to the other lures, differences were not significant. The visual stimulus (trap design) used had a significant effect on capture, with a Ladd trap (red sphere on a yellow panel) being considerably more effective than the other traps. We discuss the implications of this study, including why the degree of effectiveness of the new lure might have differed among the test orchards (citrus, apple, stonefruit), and why yeast odours might increase attractiveness to "ripening fruit" volatile blends under field conditions.

Comparison of Monitoring Systems and Temporal Activity Patterns for Spotted-Wing Drosophila (Diptera: Drosophilidae): Implications for Integrated Pest Management

Abstract Spotted-wing drosophila, Drosophila suzukii (Matsumura), is a significant, global invasive species first confirmed in the United States in 2008. Since the first detection in Minnesota in 2012, D. suzukii rapidly became a major economic pest of berry crops in the state. Effective monitoring of adult D. suzukii populations is a crucial aspect of developing integrated pest management (IPM) programs for at-risk crops. Drosophila suzukii monitoring research was conducted in 2016 and 2017 to better understand the effectiveness of two commercially available trapping systems for early detection of adults in spring and how mean trap catches compared over time. In addition, using the Scentry trap, we assessed the impact of lure age on trap performance. Finally, a study was conducted to better understand the diurnal activity pattern for adult D. suzukii under Minnesota summer conditions. Results comparing the trapping systems indicated each system varied in its ability to detect first catch of D. suzukii but that both commercial traps/lures were effective. The lure age study showed that lures can be changed less frequently than initially suggested. Temporal activity studies, as measured by trap catch via Scentry traps, indicated that adult D. suzukii demonstrated a crepuscular activity pattern in raspberry and blueberry. The results of these studies should benefit growers as they continue to fine-tune fruit IPM programs for D. suzukii.

Control of spotted wing drosophila (Drosophila suzukii) in sweet cherry and raspberry using bait sprays

Spotted wing drosophila (Drosophila suzukii Matsumura) is a major pest of fruit crops with global significance. Effective control is reliant on uniformly spraying insecticides on all crop foliage. To encourage pest attraction and ingestion of insecticides, phagostimulant baits can be employed in ‘attract and kill’ strategies. In semi-field trials, we compared (1) full-field foliar sprays of two insecticides spinosad and cyantraniliprole, with (2) reduced [40%] and (3) low [4%] rates of the insecticides to control D. suzukii and reduce insecticide residues in fruit in sweet cherry and raspberry. The low rates of the insecticides were also combined with baits, (4) Combi-protec, a proprietary mixture of plant extracts, proteins and sugars and (5) molasses; treatment (6) was an untreated control. In both crops, when combined with baits, low rates of insecticides gave comparable control of D. suzukii in fruits compared with the full-rate sprays in most cases, and D. suzukii was significantly lower in these treatments compared with the untreated controls. Crop spray coverage was eight and thirty times higher in the full-rate applications compared with the bait and low-rate sprays, in raspberry and cherry, respectively. The reduction in applied insecticide was achieved by lower concentrations and volumes and a narrower band spray applied across the middle of the crop canopy. Spinosad and cyantraniliprole residues were detected in cherries taken from trees sprayed with full-rate applications but not in fruit from trees given the low rates of insecticides with bait. This study demonstrates that bait sprays can be effectively employed on crops with complex canopies for D. suzukii control.

Characterization of Triadica sebifera (L.) Small Extracts, Antifeedant Activities of Extracts, Fractions, Seed Oil and Isolated Compounds against Plutella xylostella (L.) and Their Effect on Detoxification Enzymes.

Plutella xylostella L. is one of the world’s major pests of cruciferous crops. The indiscriminate use of synthetic insecticides has led to insecticide resistance and resurgence, and has been harmful to non-target organisms and the environment. Botanical insecticides are the best alternatives to synthetic pesticides for the management of pests in organic agriculture and integrated management. T. sebifera is an invasive species and has good potential as an insecticide due to the availability of plant material in some parts of India. The antifeedant activities of T. sebifera have not been reported against P. xylostella and other lepidopteron insects to date. Therefore, the current study targeted the characterization of leaf and bark extracts, feeding deterrence, synergistic and detoxification enzyme activities of leaf/bark ethanolic extracts/fractions, seed oil, and isolated compounds. UHPLC-QTOF-IMS analysis showed that shikimic acid, xanthoxylin, quercetin, kaempferol, methyl gallate, and stigmasterol are common metabolites identified in leaf and bark extracts. The combination of seed oil with bark extract showed higher deterrence (DC50 = 317.10 mg/L) as compared to leaf/bark extracts alone. Gallic acid showed higher deterrence (67.48%) than kaempferol and quercetin. The n-butanol fraction of bark was more repellent (RC50 = 414.61 mg/L). Based on DC50, the seed oil with leaf extract (1:1 ratio) alone with choice and seed oil with leaf and bark extract without choice showed synergistic interaction, but seed oil with bark extract with choice showed additive interaction. The ethanol extract of leaf, bark, and seed oil inhibited GST and AChE in P. xylostella. The leaf extract and seed oil or their combinations may be recommended as antifeedants to reduce damage by P. xylostella based on persistence, antifeedant, phytotoxicity, safety to predators/parasitoids, etc., under field conditions.

Mutation of a lepidopteran-specific PMP-like protein, BmLSPMP-like, induces a stick body shape in silkworm, Bombyx mori.

Lepidoptera is one of the largest orders of insects, some of which are major pests of crops and forests. The cuticles of lepidopteran pests play important roles in defense against insecticides and pathogens, and are indispensable for constructing and maintaining extracellular structures and locomotion during their life cycle. Lepidopteran-specific cuticular proteins could be potential targets for lepidopteran pest control. But information on this is limited. Our research aimed to screen the lepidopteran-specific cuticular proteins using the lepidopteran model, the silkworm, to explore the molecular mechanism underlying the involvement of cuticular proteins in body shape construction. Positional cloning showed that BmLSPMP-like, a gene encoding a lepidopteran-specific peritrophic matrix protein (PMP) like protein which includes a peritrophin A-type chitin-binding domain (CBM_14), is responsible for the stick (sk) mutation. BmLSPMP-like is an evolutionarily conserved gene that exhibits synteny in Lepidoptera and underwent purifying selection during evolution. Expression profiles demonstrated that BmLSPMP-like is expressed in chitin-forming tissues, testis and ovary, and accumulates in the cuticle. BmLSPMP-like knockout, generated with CRISPR/Cas9, resulted in a stick-like larval body shape phenotype. Over-expression of BmLSPMP-like in the sk mutant rescued its abnormal body shape. The results showed that BmLSPMP-like may be involved in assemblage in the larval cuticle. Our results suggested that the dysfunction of BmLSPMP-like may result in a stick body shape phenotype in silkworm, through the regulation of the arrangement of the chitinous laminae and cuticle thickness. Our study provides new evidence of the effects of LSPMP-likes on lepidopteran body shape formation, metamorphosis and mortality, which could be an eco-friendly target for lepidopteran pest management. © 2022 Society of Chemical Industry.

Molecular and behavioral studies reveal differences in olfaction between winter and summer morphs of Drosophila suzukii.

Spotted-wing drosophila, Drosophila suzukii (Matsumura), is a major economic pest of several fruit crops in Europe, North and South America, and other parts of the world because it oviposits in ripening thin-skinned fruits. This vinegar fly exhibits two distinct morphotypes: a summer and a winter morph. Although adaptations associated with the winter morph enhance this invasive pest’s capacity to survive in cold climates, winter is still a natural population bottleneck. Since monitoring early spring populations is important for accurate population forecasts, understanding the winter morph’s response to olfactory cues may improve current D. suzukii management programs. In this study, a comparative transcriptome analysis was conducted to assess gene expression differences between the female heads of the two D. suzukii morphs, which showed significant differences in 738 genes (p ≤ 0.0001). Out of twelve genes related to olfaction determined to be differentially expressed in the transcriptome, i.e., those related to location of food sources, chemosensory abilities, and mating behavior, nine genes were upregulated in the winter morph while three were downregulated. Three candidate olfactory-related genes that were most upregulated or downregulated in the winter morph were further validated using RT-qPCR. In addition, behavioral assays were performed at a range of temperatures to confirm a differing behavioral response of the two morphs to food odors. Our behavioral assays showed that, although winter morphs were more active at lower temperatures, the summer morphs were generally more attracted to food odors. This study provides new insights into the molecular and behavioral differences in response to olfactory cues between the two D. suzukii morphs that will assist in formulating more effective monitoring and physiological-based control tools.

Potential of Silicon to Improve Biological Control of Fall Armyworm, Spodoptera frugiperda on Maize

Silicon (Si) accumulation in plants confers a mechanical barrier to insect herbivory and may alter plant chemistry to increase the attraction of natural enemies to host insect herbivores on Si−treated plants. The fall armyworm (FAW), Spodoptera frugiperda, is a major insect pest of grain crops, including maize (Zea mays L.). This study examined whether Si supplementation alters maize volatile compounds that mediate host location in Euthyrhynchus floridanus, a generalist predator of FAW. A four-arm olfactometer was used to test the olfactory preference of nymphs and adults of E. floridanus to the odor of maize leaf materials from plants that were; Si−treated and infested, Si−treated without infestation, Si−deprived and infested, and Si−deprived without infestation. The probabilities of individual insects choosing between the four treatments were estimated using a multinomial generalized linear mixed model. There were no statistical differences in the olfactory preference of E. floridanus between Si−treated and Si−deprived maize leaf materials. However, the median estimate showed that nymphs were almost twice likely to be attracted to Si−supplemented leaf material, indicating a potential positive effect of Si. However, a more robust follow-up study is needed to further assess the impact of Si on E. floridanus.

Field, semi‐field and greenhouse testing of HOOK SWD, a SPLAT‐based attract‐and‐kill formulation to manage spotted‐wing drosophila

AbstractNative to Southeast Asia, the spotted‐wing drosophila (Drosophila suzukii) has become a major pest of small fruit crops in the Americas and Europe because females can oviposit in ripening fruit. Currently, D. suzukii management relies heavily on chemical control; thus, more sustainable approaches like attract‐and‐kill need to be evaluated to reduce insecticide use. In previous studies, HOOK SWD, an attract‐and‐kill product that combines attractants, phagostimulants and an insecticide (spinosad), showed promise for D. suzukii control; still, little is known about its performance under field conditions and under varying pest and host‐fruit densities, as well as its residual activity. Here, we evaluated the efficacy of HOOK SWD when applied in commercial blueberry farms, when deployed in semifield cages under different D. suzukii adult and fruit densities and when aged for 30 days in the greenhouse. Results from field experiments showed that HOOK SWD could reduce fruit infestation in blueberry farms; however, its efficacy varied in space and time. Semifield cage studies revealed that relatively high densities of both D. suzukii adults and fruit can reduce the effectiveness of HOOK SWD, which might explain the variation in its efficacy in the field. Ageing HOOK SWD in a greenhouse for at least 30 days yielded no significant decrease in insecticidal activity. Altogether, these studies show that HOOK SWD can potentially suppress D. suzukii populations in the field, but it should be used as part of an integrated pest management program instead of a stand‐alone control tool, especially under high pest and fruit densities.

Evaluation of chemical and microbial control options for Pangaeus bilineatus (Say) (Hemiptera: Cydnidae) infesting peanut crop.

The peanut burrower bug, Pangaeus bilineatus is a major crop pest of peanuts in the southern United States. Peanuts infested by P.bilineatus exhibit weight and quality losses and could be discounted by ≤50% of the prevailing market price. Control of this pest is difficult because it attacks peanut pods underground, thus rendering foliar pesticide applications ineffective. Integration of entomopathogenic fungi and nematodes (EPF/EPNs) with chemical insecticides in the management of P.bilineatus was investigated as a potential integrated pest management containment tool. The nymphs were less susceptible than adults of P.bilineatus to EPNs. Comparison of six strains of both Heterorhabditis spp. and Steinernema spp. demonstrated that Steinernema carpocapsae (All) was the most virulent EPN, causing 75.54% mortality of P.bilineatus adults after 7 days postinoculation (dpi), whereas the mortality generated by the application of the rest of the nematodes ranged between 17.03% (H.bacteriophora - Lewis) and 50% (H.bacteriophora VS). Application of imidacloprid by itself at ½FR (field rate) did not result in any significant mortality of P.bilineatus adults but application of chlorpyrifos at 1/8FR caused significant mortality (27.41-61.35%) at 7-14 dpi. However, combined applications of S.carpocapsae and imidacloprid resulted in significant mortality starting at 3dpi. The interactions between S.carpocapsae and imidacloprid were synergistic at 3-5dpi, but became additive at 7-14 dpi. Both chlorpyrifos and imidacloprid did not negatively impact the reproduction of S.carpocapsae. The compatibility between S.carpocapsae and imidacloprid makes a case for the combination to be used for the management of P.bilineatus. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Effects of Ultraviolet B on The Efficacy of Bacillus thuringiensis var. kurstaki Formulations Against Tobacco Armyworm, Spodoptera litura (Lepidoptera: Noctuidae)

Tobacco armyworm (Spodoptera litura Fab.) is one of the major insect pests of crops in Indonesia. The management of this pest still depends on the use of chemical insecticides. The use of bio-insecticides, such as Bacillus thuringiensis (Bt.), are known to be alternatives, but it easily degraded by sunlight. This research aimed to study the effects of UV B on Bt. pathogenicity and to explore plant-based additives as UV B protectants for Bt. against armyworm. Thirteen plant extracts were screened based on their UV spectra absorbencies using UV spectrophotometry. The extracts, namely cloves, Jicama, Celebes pepper, turmeric, and Moringa, then used for the formulations of Bt. and exposed under UV B lights for 0, 72, and 144 h. After exposure to UV B, Bt. formulations were tested for bioassay against one- day-old 1st and one day old 2nd larval instars of tobacco armyworm. The result indicated that at 72 and 144 h of UV B exposures, the Bt. added formulations were signifcantly different compared to Bt. alone. At 72 h exposure against the 2nd larval instar, the larval mortality of tobacco armyworm on the second day of observation on Bt. formulated with Celebes pepper and turmeric was 97.3 and 80%, respectively, whereas, at 144 h exposure, the mortality was 96 and 89.3%, respectively. This study concluded that Celebes pepper and turmeric extracts were the potential to be used as the Bt. protectants against UV B.

A Chromosome-Scale Genome Assembly of a Helicoverpa zea Strain Resistant to Bacillus thuringiensis Cry1Ac Insecticidal Protein.

Helicoverpa zea (Lepidoptera: Noctuidae) is an insect pest of major cultivated crops in North and South America. The species has adapted to different host plants and developed resistance to several insecticidal agents, including Bacillus thuringiensis (Bt) insecticidal proteins in transgenic cotton and maize. Helicoverpa zea populations persist year-round in tropical and subtropical regions, but seasonal migrations into temperate zones increase the geographic range of associated crop damage. To better understand the genetic basis of these physiological and ecological characteristics, we generated a high-quality chromosome-level assembly for a single H. zea male from Bt-resistant strain, HzStark_Cry1AcR. Hi-C data were used to scaffold an initial 375.2 Mb contig assembly into 30 autosomes and the Z sex chromosome (scaffold N50 = 12.8 Mb and L50 = 14). The scaffolded assembly was error-corrected with a novel pipeline, polishCLR. The mitochondrial genome was assembled through an improved pipeline and annotated. Assessment of this genome assembly indicated 98.8% of the Lepidopteran Benchmark Universal Single-Copy Ortholog set were complete (98.5% as complete single copy). Repetitive elements comprised approximately 29.5% of the assembly with the plurality (11.2%) classified as retroelements. This chromosome-scale reference assembly for H. zea, ilHelZeax1.1, will facilitate future research to evaluate and enhance sustainable crop production practices.