The rise of RNAi-based biopesticides marks a turning point in pest control, prompting reflection on the future role of Bacillus thuringiensis (Bt). Far from being outdated, Bt remains a cornerstone of sustainable agriculture, with proven efficacy, safety, and public trust. This opinion piece advocates for Bt’s continued relevance in an RNAi-driven future, urging a complementary, not competitive, view of both technologies within integrated pest management frameworks.

The environmental impact of exotic insect pest species is often poorly quantified, making current pest management strategies obsolete. The fall armyworm (FAW) is endemic to the Western hemisphere - where it is considered a major pest of maize - and invasive to Africa, Asia and Oceania since 2016, 2018 and 2020, respectively. FAW's highly polyphagous behaviour and potential expansion of its host range in invaded habitats may put some non-crop flowering plants and their ecosystem services at risk. While its potential for intraguild competition and hybridisation with endemic maize pest species could have important consequences for pest population dynamics and pest management, a FAW inter-strain hybrid - resistant to pesticides - has already been documented in China. Integrated pest management (IPM) combines host plant resistance, agronomic practices and biological control for the long-term prevention of pests. Within invaded areas, a lack of knowledge of FAW's ecological adaptations, the absence of resistant cultivars, and an insufficient build-up of natural enemies provide challenges that translate into research opportunities to support IPM solutions for this exotic pest species.

Cotton is a vital cash crop because it is a key raw material for the textile industry, but its yield can be drastically reduced by insect pests. As of 2015, the pink bollworm (PBW), Pectinophora gossypiella, has emerged as a major insect pest on transgenic cotton in Pakistan. Bt. transgenic cotton lines expressing Cry1Ac toxin are widely used against Helicoverpa armigera and some Heliothis spp. but have reduced efficacy against the PBW. The use of chemical controls such as insecticide sprays is still an integral part of PBW management, but their potential negative effects on natural enemies that help keep bollworm populations in check must be evaluated. During the 2017-18 and 2018-19 growing seasons, field experiments were conducted to compare the effectiveness of various insecticides on Bt. and non-Bt. cotton against PBW. When tested against PBW, triazophos was found to be the most toxic insecticide, followed by the synthetic pyrethroids bifenthrin and deltamethrin, and chlorpyrifos from the organophosphate group. Plastic cups surface treated PBW moth bioassays with the same insecticides showed that Triazophos was the most toxic insecticide to the moths of pink bollworm with less LC50 values, i.e., 27.98 mg/L followed by deltamethrin (43.30 mg/L), bifenthrin (62 mg/L), and chlorpyriphos (255 mg/L). It could be concluded that insecticides, which are responsible for larval and moth mortality, gave better control because of the concealed behavior of larvae after hatching from the eggs. It is recommended to use these insecticides in rotation with each other for optimal PBW control. Significantly larger populations of spiders, green lacewings, and Geocoris species were recorded after treatment with triazophos compared to other insecticides. However, integrated approaches could be the best strategy for PBW management, like Bt cotton, the male disrupting technique employing pheromones (PB-ropes) at the flowering stage and one or two applications of insecticides. Insecticide applications at the end of the season would protect the crop next year from overwintering larvae which are the main source of infestation in the subcontinent and Indo-Pakistan region.

Overuse of pesticides can result in the development of resistance, secondary pest outbreaks, and pest resurgence due to a reduction in natural enemies. The present study compares the residual toxicity of lambda-cyhalothrin, a relatively nonselective insecticide, with abamectin, indoxacarb, and spinosad, compounds which have been reported to be less harmful to arthropod natural enemies. Two key cosmopolitan pests of crucifer crops, (Plutella xylostella) and (Myzus persicae), and two of their respective hymenopteran parasitoids, (Cotesia vestalis) and (Aphidius colemani) were used as representative pests and natural enemies. The pyrethroid lambda-cyhalothrin was found to be the most persistent toxicant against both pest and both parasitoid species tested, while the lactones abamectin and spinosad were the least persistent toxicants. A leaf wax stripping technique was used to compare the contact toxicity of insecticide residues against adult C. vestalis and A. colemani in the epicuticular wax layer. For each compound, removal of epicuticular wax reduced the 24 h residual toxicity (LC50) of fresh deposits (day 0) by about an order of magnitude against C. vestalis. A second residual toxicity experiment showed that removal of epicuticular wax significantly reduced the residual toxicity of each compound against A. colemani at 0, 7, and 14 d after application, with little or no detectable residual activity for the oxadiazine indoxacarb or abamectin/spinosad respectively after 14 d. The present data supports the view that in addition to the intrinsic toxicity of insecticides to natural enemies, differences in their persistence as foliar residues should also be considered in IPM systems.

We examined differences in the physiology and life history between dimorphs of the common pistachio psyllid, Agonoscena pistaciae (Burckhardt and Lauterer) (Hemiptera: Aphalaridae), and how they differ in elicitating host plant production of key metabolites and volatile compounds involved in the recruitment of herbivores and natural enemies. Summer morphs had higher activities of glutathione S-transferase, carboxylesterase, acetylcholinesterase, and cytochrome P450 monooxygenase, superoxide dismutase, catalase, peroxidase, phenoloxidase, and a higher total protein content compared to winter morphs, whereas the latter had higher amounts of lipid, carbohydrate, and glycogen. Winter morphs were heavier, with a higher chitin content and longer preoviposition period, but greater fecundity and longevity than summer morphs. A lower LC50 to thiamethoxam for winter morphs resulted in higher mortality following exposure to the recommended rate of this insecticide in a greenhouse trial. Feeding by winter morphs elicited more strongly the release of volatile compounds known to be attractive to other herbivores, whereas feeding by summer morphs elicited more strongly the release of volatiles implicated in the attraction of natural enemies. Feeding by psyllids increased the concentrations of nitrogenous compounds, carbohydrates, vitamins, and amino acids in plants, the winter morph eliciting larger changes and more improved host plant quality. We conclude that winter morphs are more vulnerable targets for chemical control in early spring, whereas management of summer morphs could rely more on conservation biological control.

The spore-forming bacterium Bacillus thuringiensis (Bt) of the Bacillus cereus group uses toxin-opened breaches at the insect midgut epithelium to infest the hemolymph, where it can rapidly propagate despite antimicrobial host defenses and induce host death by acute septicemia. The response of Bt to host hemolymph and the latter's role in bacterial pathogenesis is an area that needs clarification. Here, we report a proteomic analysis of the Bt kurstaki strain HD73 (Btk) hemolymph stimulon showing significant changes in 60 (34 up- and 26 downregulated) differentially accumulated proteins (DAPs). Gene ontology (GO) enrichment analysis revealed that DAPs were mainly related to glutamate metabolism, transketolase activity, and ATP-dependent transmembrane transport. KEGG analysis disclosed that DAPs were highly enriched in the biosynthesis of bacterial secondary metabolites, ansamycins. Interestingly, about 30% of all DAPs were in silico predicted as putative virulence factors. Further characterization of hemolymph effects on Btk showed enhanced autoaggregation in liquid cultures and biofilm formation in microtiter polystyrene plates. Hemolymph-exposed Btk cells were less immunogenic in mice, suggesting epitope masking of selected surface proteins. Bioassays with intrahemocoelically infected Bombyx mori larvae showed that hemolymph preexposure significantly increased Btk toxicity and reproduction within the insect (spore count per cadaver) at low inoculum doses, possibly due to 'virulence priming'. Collectively, our findings suggest that the Btk hemolymph stimulon could be partially responsible for bacterial survival and propagation within the hemolymph of infected insects, contributing to its remarkable success as an entomopathogen. All mass spectrometry data are available via ProteomeXchange with identifier PXD021830. IMPORTANCE After ingestion by a susceptible insect and damaging its midgut epithelium, the bacterium Bacillus thuringiensis (Bt) reaches the insect blood (hemolymph), where it propagates despite the host's antimicrobial defenses and induces insect death by acute septicemia. Although the hemolymph stage of the Bt toxic pathway is determinant for the infested insects' fate, the response of Bt to hemolymph and the latter's role in bacterial pathogenesis has been poorly explored. In this study, we identified the bacterial proteins differentially expressed by Bt after hemolymph exposure. We found that about 30% of hemolymph-regulated Bt proteins were potential virulence factors, including manganese superoxide dismutase, a described inhibitor of hemocyte respiratory burst. Additionally, contact with hemolymph enhanced Bt virulence phenotypes, such as cell aggregation and biofilm formation, altered bacterial immunogenicity, and increased Bt toxicity to intrahemocoelically injected insects.

Background The Plutella xylostella PxSDF2L1 gene was previously reported to enhance insect resistance to pathogen at high basal transcription rate. PxSDF2L1 shows similitude with the stromal cell-derived factor 2 (SDF2), an ER stress-induced chaperon protein that is highly conserved throughout animals and plants. The precise biological function of SDF2 is not clear, but its expression is required for innate immunity in plants. Here, we investigate whether a continuous expression of PxSDF2L1 in Nicotiana benthamiana can similarly confer resistance to plant pathogen, particularly, the black shank Phytophthora parasitica var. nicotianae . Results The N. benthamiana plants were inoculated with agrobacteria transformed with a PVX-based binary vector carrying the PxSDF2L1 gene; similar agroinoculation experiments with a PVX vector carrying the GFP gene were used for controls. In pot trials, agroinfected N. benthamiana plants constitutively expressing PxSDF2L1 showed a significant reduction of stem disease symptoms caused by the inoculation with P. parasitica , compared with controls. Conclusions We confirm a role of PxSDF2L1 in resistance to black shank, with a potential application to engineering active resistance against this oomycete in the commercial N. tabacum species and propose its evaluation in other crop families and plant pathogens.

The widespread use of transgenic plants imposes selection pressure on insect pest populations to develop insecticide resistance. Evaluation of effectiveness of resistance management strategies is very important in resistance management programs. Resistance management to insecticides is widely believed to depend in part on associated fitness costs. Fitness costs can delay the development of resistance. In the present study, the effects of two entomopathogenic nematode species, Steinernema carpocapsae and Heterorhabditis bacteriophora were studied on the fitness of first insect population of Heliothis virescens selected with Vip3A in the laboratory. It was found that both nematodes species increased the fitness cost of Vip3A selected insects. The mortality of the Unsel subpopulation after exposure to either nematode species was significantly lower than that of the Vip3A-Sel subpopulation. Likewise, the reproduction of both nematode species was significantly greater in cadavers of the Unsel compared with the Vip3A-Sel subpopulation of H. virescens. There was positive correlation between nematode reproduction and the larval instar infected with nematodes. The penetration of infective nematode juveniles (IJ) was greater in the Vip3A-Sel subpopulation than in the Unsel subpopulation of H. virescens. It is concluded that entomopathogenic nematodes could increase the fitness costs and subsequently delay the resistance.

The Vip3Aa insecticidal protein from Bacillus thuringiensis (Bt) is produced by specific transgenic corn and cotton varieties for efficient control of target lepidopteran pests. The main threat to this technology is the evolution of resistance in targeted insect pests, thus understanding the mechanistic basis of resistance is crucial to deploy the most appropriate strategies for resistance management. In this work, a laboratory-selected colony of Heliothis virescens (Vip-Sel) highly resistant to the Vip3Aa protein was used to test whether an alteration of membrane receptors in the insect midgut might explain the resistance phenotype. Binding of 125I-labeled Vip3Aa to brush border membrane vesicles (BBMV) from 3rd instar larvae from Vip-Sel was not significantly different from binding in the reference susceptible colony. Interestingly, BBMV from Vip-Sel larvae show dramatically reduced levels of alkaline phosphatase activity, which was further confirmed by a strong down-regulation of the membrane-bound alkaline phosphatase 1 ( HvmALP1 ) gene. However, its involvement as a receptor for the Vip3Aa protein was not supported by ligand blotting and viability assays with insect cells expressing HvmALP1 . These data support that reduced alkaline phosphatase, previously observed in insect colonies resistant to Cry proteins from Bt, may also serve as an indirect marker that is not mechanistically involved in resistance to Vip3Aa. IMPORTANCE The Vip3Aa insecticidal protein remains the only lepidopteran-specific trait in transgenic Bt crops with no cases of field-evolved resistance. While laboratory-selected resistance to Vip3A has been reported elsewhere, the mechanism for resistance is unknown. Results in this work show lack of significant Vip3Aa binding alterations in resistant and reference colonies of H. virescens. These observations are in contrast to most cases of high levels of resistance to insecticidal Bt proteins for which decreased binding is commonly detected. In addition, this study provides the first evidence of down-regulation of membrane bound alkaline phosphatase (mALP) associated with Vip3Aa resistance, a phenomenon commonly associated with resistance to Cry proteins from Bt. Results from this work suggest that mALP down-regulation may be a useful biomarker yet reject its direct participation in resistance to Vip3Aa.

The Vip3Aa insecticidal protein from Bacillus thuringiensis (Bt) is produced by specific transgenic corn and cotton varieties for efficient control of target lepidopteran pests. The main threat to this technology is the evolution of resistance in targeted insect pests and understanding the mechanistic basis of resistance is crucial to deploy the most appropriate strategies for resistance management. In this work, we tested whether alteration of membrane receptors in the insect midgut might explain the >2000-fold Vip3Aa resistance phenotype in a laboratory-selected colony of Heliothis virescens (Vip-Sel). Binding of 125I-labeled Vip3Aa to brush border membrane vesicles (BBMV) from 3rd instar larvae from Vip-Sel was not significantly different from binding in the reference susceptible colony. Interestingly, BBMV from Vip-Sel larvae showed dramatically reduced levels of membrane-bound alkaline phosphatase (mALP) activity, which was further confirmed by a strong downregulation of the membrane-bound alkaline phosphatase 1 (HvmALP1) gene. However, the involvement of HvmALP1 as a receptor for the Vip3Aa protein was not supported by results from ligand blotting and viability assays with insect cells expressing HvmALP1.

Wetlands provide multiple services to human societies. Despite policies dedicated to their protection, current European policies do not address the need to balance mosquito management approaches to mitigate dis-services to human health and well-being while ensuring that wetland conservation goals are met. Herein, we outline criteria for consideration when developing mosquito control programmes in European wetlands that will allow managers and public health authorities to adopt effective and ecologically sound approaches. Synthesis and applications. The proposed code of practice provides practical advice to local authorities and those involved in mosquito control in order to design an integrated mosquito management strategy that aligns with current environmental legislation. Although this code of practice was developed by European experts, it is transferable to other geographical contexts, integrating the expertise and knowledge of local stakeholders and researchers from the fields of medical entomology, human and animal health and ecology.

Peritrophins are associated with structural and functional integrity of peritrophic membranes (PM), structures composed of chitin and proteins. PM lines the insect midgut and has roles in digestion and protection from toxins. We report the full-length cDNA cloning, molecular characterization and functional analysis of SfPER, a novel PM peritrophin A protein, in Spodoptera frugiperda . The predicted amino acid sequence indicated SfPER’s domain structure as a CMCMC-type, consisting of a signal peptide and three chitin-binding (C) domains with two intervening mucin-like (M) domains. Phylogenetic analysis determined a close relationship between SfPER and another S. frugiperda PM peritrophin partial sequence. SfPER transcripts were found in larvae and adults but were absent from eggs and pupae. Chitin affinity studies with a recombinant SfPER-C1 peritrophin A-type domain fused to SUMO/His-tag confirmed that SfPER binds to chitin. Western blots of S. frugiperda larval proteins detected different sized variants of SfPER along the PM, with larger variants found towards the posterior PM. In vivo suppression of SfPER expression did not affect susceptibility of larvae to Bacillus thuringiensis toxin, but significantly decreased pupal weight and adult emergence, possibly due to PM structural alterations impairing digestion. Our results suggest SfPER could be a novel target for insect control.

the pattern of nutrient inputs and by indirect effects through changes in plant species composition. However, we could not entirely discount that the pesticide used to exclude invertebrates may have affected some microbial community measures. Nevertheless, our work illustrates that human activity that affects grazing intensity may affect ecosystem functioning and sustainability, as regulated by multi‐trophic interactions between above‐ and below‐ground communities.

Multi-toxin Bt-crops expressing insecticidal toxins with different modes of action e.g. Cry and Vip, are expected to improve resistance management in target pests. While Cry1A resistance has been relatively well characterized in some insect species, this is not the case for Vip3A, for which no mechanism of resistance has yet been identified. Here we applied HT-SuperSAGE to analyze the transcriptome of the gut tissue of tobacco budworm Heliothis virescens (F.) laboratory-selected for Vip3Aa resistance. From a total of 1 324 252 sequence reads, 58951 26-bp tags were obtained representing 17 751 non-singleton unique transcripts (UniTags) from genetically similar Vip3Aa-resistant (Vip-Sel) and susceptible control (Vip-Unsel) strains. Differential expression was significant (≥ 2.5-fold or  0.4; P<0.05) for 1989

Multitoxin Bt-crops expressing insecticidal toxins with different modes of action, for example, Cry and Vip, are expected to improve resistance management in target pests. While Cry1A resistance has been relatively well characterized in some insect species, this is not the case for Vip3A, for which no mechanism of resistance has yet been identified. Here we applied HT-SuperSAGE to analyze the transcriptome of the gut tissue of tobacco budworm Heliothis virescens (F.) laboratory-selected for Vip3Aa resistance. From a total of 1 324 252 sequence reads, 5 895 126-bp tags were obtained representing 17 751 nonsingleton unique transcripts (UniTags) from genetically similar Vip3Aa-resistant (Vip-Sel) and susceptible control (Vip-Unsel) strains. Differential expression was significant (>= 2.5 fold or <= 0.4; P < 0.05) for 1989 sequences (11.2% of total UniTags), where 420 represented overexpressed (OE) and 1569 underexpressed (UE) genes in Vip-Sel. BLASTN searches mapped 419 UniTags to H. virescens sequence contigs, of which, 416 (106 OE and 310 UE) were unambiguously annotated to proteins in NCBI nonredundant protein databases. Gene Ontology distributed 345 of annotated UniTags in 14 functional categories with metabolism (including serine-type hydrolases) and translation/ribosome biogenesis being the most prevalent. A UniTag homologous to a particular member of the REsponse to PAThogen (REPAT) family was found among most overexpressed, while UniTags related to the putative Vip3Aa-binding ribosomal protein S2 (RpS2) were underexpressed. qRT-PCR of a subset of UniTags validated the HT-SuperSAGE data. This study is the first providing lepidopteran gut transcriptome associated with Vip3Aa resistance and a foundation for future attempts to elucidate the resistance mechanism.

Laboratory selection with Vip3Aa of a field-derived population of Heliothis virescens produced >2,040-fold resistance in 12 generations of selection. The Vip3Aa-selected (Vip-Sel)-resistant population showed little cross-resistance to Cry1Ab and no cross-resistance to Cry1Ac. Resistance was unstable after 15 generations without exposure to the toxin. F1 reciprocal crosses between Vip3Aa-unselected (Vip-Unsel) and Vip-Sel insects indicated a strong paternal influence on the inheritance of resistance. Resistance ranged from almost completely recessive (mean degree of dominance [h] = 0.04 if the resistant parent was female) to incompletely dominant (mean h = 0.53 if the resistant parent was male). Results from bioassays on the offspring from backcrosses of the F1 progeny with Vip-Sel insects indicated that resistance was due to more than one locus. The results described in this article provide useful information for the insecticide resistance management strategies designed to overcome the evolution of resistance to Vip3Aa in insect pests.IMPORTANCEHeliothis virescens is an important pest that has the ability to feed on many plant species. The extensive use of Bacillus thuringiensis (Bt) crops or spray has already led to the evolution of insect resistance in the field for some species of Lepidoptera and Coleoptera. The development of resistance in insect pests is the main threat to Bt crops. The effective resistance management strategies are very important to prolong the life of Bt plants. Lab selection is the key step to test the assumption and predictions of management strategies prior to field evaluation. Resistant insects offer useful information to determine the inheritance of resistance and the frequency of resistance alleles and to study the mechanism of resistance to insecticides.

INTRODUCTION:Latissimus dorsi miniflap is a breast-conserving volume replacement technique for the reconstruction of large breast defects. While mammographic features of miniflap reconstruction have been described, little is known about the incidence, mode of presentation and size of local recurrence after this procedure. This study aimed to investigate the impact of latissimus dorsi miniflap reconstruction on the frequency, presentation and detection of local recurrence. METHODS:Clinical, radiological and pathological data were reviewed in 261 patients. Complete records were available for 11 patients developing local recurrence, including mode, time of presentation and size of the recurrent tumours. All mammograms before and after local recurrence were assessed in relation to a range of specific characteristics including parenchymal density, flap visibility, architectural distortion, mass, calcifications, fat necrosis, skin thickening and breast oedema. RESULTS:Twenty-one patients developed local recurrence at 10.4 years following reconstruction (mean age 49 years, resection weight 182 g and tumour size 33 mm). Following radiotherapy, 0.5% of patients developed local recurrence each year, which increased five-fold when radiotherapy was omitted (HR 4.99). Local recurrences were diagnosed in five patients by mammography alone, in three by mammography and palpable lump, and in three by palpable lump alone. They were detected when small (15 mm) and were associated with new mammographic abnormalities in 10 patients. CONCLUSIONS:Long follow-up demonstrates that latissimus dorsi miniflap reconstruction allows oncologically safe breast conservation when combined with postoperative radiotherapy. Local recurrences are detected early, either by mammography, clinical examination or both, and detection is not compromised by the presence of a flap.

Previous research suggests that potato cultivars offer little aphid resistance. However, few studies have measured the effects of host cultivar on aphid age dependent life table statistics or related these measures to field performance. In this study, laboratory and field studies assessed four commercial potato cultivars (Anya, Desiree, Pink Fir Apple, Santé) for resistance to Myzuspersicae. Cultivars were found to show considerable differences in resistance. In the laboratory, the intrinsic rate of increase (r m) and effective fecundity of M. persicae was lowest on cv. Anya and highest on cv. Desiree. Aphids also took longer to develop to adults and were smaller in size on Anya compared with Desiree. Field studies over two seasons found that M. Persicae infestations started earlier on Desiree than on Anya and that the greatest weekly counts were recorded on the former.

The widespread and intensive use of conventional pesticides, particularly insecticides, presents a major risk to natural enemies of target pests, as well as to the environment in general. The aim of this study was to investigate the differential intrinsic toxicity of insecticides to two key pests of crucifers, Plutella xylostella and Myzus persicae and their respective hymenopteran parasitoids, Cotesia vestalis and Aphidius colemani. Such knowledge can help inform effective integration of insecticides and biological control in IPM systems. Three insecticides generally regarded as being compatible with natural enemies (abamectin, spinosad and indoxacarb) and one compound regarded as harmful to natural enemies (lambdacyhalothrin) were examined. A comparative measure of the intrinsic toxicity of fresh deposits of insecticides on Chinese cabbage leaf discs was determined for both pest and parasitoids species after exposure to insecticide for 24 h and 120 h, and after 24 h exposure to insecticide plus 96 h on untreated leaf discs. Differences in the susceptibility of pests and parasitoids to different insecticides were marked for R xylostella and C vestalis, LC50 values being significantly lower for the pest species. Such differences were not observed for M. persicae and A. colemani. There was a direct relationship between dose, exposure time and toxicity for all insecticides tested. All insecticides tested showed lower toxicity to both parasitoids compared with P. xylostella, which suggests that for this pest species side-effects on parasitoids can be minimised through IPM practices that reduce exposure time to such non-target organisms. (C) 2016 Elsevier Ltd. All rights reserved.

Leafminer fly Liriomyza huidobrensis Blanchard (Diptera, Agromyzidae) is a key pest on potato plantation. Due to of negative impact of calendar based of pesticide application on environment and farmer health, Biological control by releasing hymenoptera parasitoid is promising as an alternative control to solve the outbreak of leafminer fly. There are two important species of hymenoptera parasitoid in lefminer population Hemiptarsenus varicornis (idiobiont ectoparasitoid) and Digliphus isaeae. idiobiont ectoparasitoid). The research objective was to determine whether multiple releasing of two parasitoid in leafminer population had significant control of leafminer fly compared than single release. The results showed that multiple release caused competition between two different behaviors of Hymenoptera parasitoid. Mortality of leafminer fly was caused by H. varicornis higher than Opius sp. In multiple or single release. The present results suggest that field releases of D. isaea would not have a detrimental effect on the indigenous species, H. varicornis, and that D. isaea may be a “good” candidate to supplement biological control of L. huidobrensis.