Mirids secrete a TOPLESS targeting protein to enhance JA-mediated defense and gossypol accumulation for antagonizing cotton bollworms on cotton plants

Most coexisting insect species exhibit stunted growth compared to individual species on plants.This phenomenon reflects an interspecific antagonism drawing extensive attention,while the underlying mechanisms remain largely uncharacterized.Mirids(Apolygus lucorum)and cotton bollworms(Helicoverpa armigera)are two common cotton pests.We identified a secretory protein,ASP1,from the oral secretion of mirids,found in the nucleus of mirid-infested cotton leaves.ASP1 specifically targets the transcriptional co-repressor TOPLESS(TPL)and inhibits NINJA-mediated recruitment of TPL,promoting plant defense response and gossypol accumulation in cotton glands.ASP1-enhanced defense inhibits the growth of cotton bollworms on cotton plants,while having limited impact on mirids.The mesophyll-feeding characteristic allows mirids to avoid most cotton glands,invalidating cotton defense.Our investigation reveals the molecular mechanism by which mirids employ cotton defense to selectively inhibit the feeding of cotton bollworms.

Functional characterization of sensory neuron membrane protein 1a involved in sex pheromone detection of Apolygus lucorum(Hemiptera:Miridae)

The mirid bug Apolygus lucorum(Hemiptera:Miridae)is a polyphagous pest that affects a wide range of host plants.Its control remains challenging mainly due to its rapid reproduction,necessitating an understanding of sex pheromone communication.The recognition of sex pheromones is vital for courtship and mating behaviors,and is mediated by various chemosensory-associated proteins.Among these,sensory neuron membrane protein(SNMP),a CD36-related protein,is suggested to play crucial roles in detecting sex pheromones.In this study,we employed transcriptomic and genomic data from A.lucorum and phylogenetic approaches,and identified four putative SNMP genes(AlucSNMP1a,AlucSNMP1b,AlucSNMP2a,and AlucSNMP2b)with full open reading frames.Expression analysis revealed the ubiquitous presence of AlucSNMP transcripts in multiple tissues,with only AlucSNMP1a exhibiting male-biased expression in the antennae,suggesting its potential role in male chemosensation.Functional analysis using the Xenopus oocyte expression system,coupled with two-electrode voltage clamp recording,demonstrated that the co-expression of AlucSNMP1a with specific pheromone receptors(PRs)and the Odorant receptor co-receptor(Orco)significantly enhanced electrophysiological responses to sex pheromones compared to the co-expression of PRs and Orco alone.Moreover,the results indicated that the presence of AlucSNMP1a not only affected the responsiveness to sex pheromones but also influenced the kinetics(activation and inactivation)of the induced signals.In contrast,the co-expression of AlucSNMP1b with AlucPR/Orco complexes had no impact on the inward currents induced by two pheromone compounds.An examination of the selective pressures on SNMP1 genes across 20 species indicated strong purifying selection,implying potential functional conservation in various insects.These findings highlight the crucial role of AlucSNMP1a in the response to sex pheromones.

Evaluation of New Insecticide （Proteus 170O - TEQ） for the Control of the Brown Cocoa Mirid （Sahlbergella Singularis） in Nigeria

Proteus 170O - TEQ insecticide was subjected through rigorous testing over years （2005 to 2008） at four concentrations 0.15% （9 mls/10L.H20）, 0.31% （18 mls/10L.H2O）, 0.46% （27 mls/10L.H2O） and 0.61% （36 mls/10L.H2O）. Each concentration was replicated three times in the field. The mortality rates of mirids on exposure to the various concentrations of Proteus and Standard miricide in the laboratory were similar at 0.46% concentration as both gave a 100% kill ofmirids at the 40th minute. The first year field mortalities of mirids recorded 24 hours after the initial and residual applications at the Ibadan, Owena and Ikom at 0.46% active ingredient concentration gave 100% kill of mirids. The mortalities of mirids recorded 24 hours after the second year field initial and residual treatments at the lowest concentration of 0.15% active ingredient ranged between 70.2% and 100%. In the third year, the insecticide at 0.31% concentration compared favourably with the Standard. The residues of thiacloprid in the analyzed cocoa bean samples were below the Limit of Quantitation （LOQ） of 0.01 mg/kg. Spraying of mature and fruiting cocoa farms at application rate of 0.46% was found adequate and recommended.

Bt Cotton in China:Are Secondary Insect Infestations Offsetting the Benefits in Farmer Fields?

The area sown to Bt cotton has expanded rapidly in China since 1997. It has effectively controlled the bollworm. However, in recent years, concern has surfaced about the emergence of secondary insect pests, particular mirids, in Bt cotton fields. This study measures the patterns of insecticide use based on farm-level from 1999 to 2006, the analysis demonstrates a rise in insecticide use to control mirids between 2001 and 2004, secondary insect infestations is largely related to the rise of mirids, but this rising did not continue in more than half of sample villages studied in 2004-2006. Moreover, the increase in insecticide use for the control of secondary insects is far smaller than the reduction in total insecticide use due to Bt cotton adoption. Further econometric analyses show that rise and fall of mirids is largely related to local temperature and rainfall.

Functional and numerical responses of Cyrtorhinus lividipennis to eggs of Nilaparvata lugens are not affected by genetically modified herbicide-tolerant rice

To safely and sustainably utilize genetic breeding techniques for crop production, greater understanding of the potential effects of genetically modified herbicide-tolerant（GMHT） crops on the ecological functions of predators is required. In the laboratory, we examined the functional and numerical responses of Cyrtorhinus lividipennis Reuter to eggs of brown planthopper（BPH）, Nilaparvata lugens（St？l）, which were reared on GMHT rice Bar68-1; the untransformed parental cultivar, D68; or a BPH-susceptive rice variety, Taichung Native 1. All stages of nymphs and female adult of C. lividipennis, either on GMHT rice or control plants, exhibited typical type II functional responses when fed on BPH eggs; the attacking rate and handling time of C. lividipennis on GMHT rice Bar68-1 was not significantly different from that on D68. The numerical responses of C. lividipennis on GMHT rice or controls fit Beddington＇s model; there were no significant differences in the parameters of numerical responses between GMHT rice Bar68-1 and D68. The results indicated that the functional and numerical responses of C. lividipennis to BPH eggs are not affected by GMHT rice Bar68-1.

The Adelphocoris lineolatus OBP4: Support for evolutionary and functional divergence of a mirid pheromone-binding protein from that found in lepidopteran moths

Pheromone-binding proteins (PBPs) have been extensively investigated in lepidopteran moths, but their evolution and function in hemipteran species remain unclear. Our previous study demonstrated that an odorant-binding protein, OBP4, of the mirid bug Adelphocoris lineolatus functions as a candidate hemipteran PBP but clustered with lepidopteran antennae-binding proteins (ABPs) rather than in the PBP/general odorant-binding protein (GOBP) clade. In this study, we hypothesized that origin and function of PBPs in hemipteran bugs may differ from those of lepidopteran moths. To test this hypothesis, we first constructed a phylogenetic tree using insect OBPs from sister hemipteran and holometabolous lineages, and the results indicated that neither OBP4 nor other types of candidate PBPs of mirid bugs clustered with the lepidopteran PBP/GOBP clade. Then, a fluorescence competitive binding assay was employed to determine binding affinities of recombinant OBP4 protein to host plant volatiles, with functional groups different from A. lineolatus sex pheromone components. The results revealed that OBP4 highly bound the female adult attractant 3-hexanone and 15 other mirid bug biologically active plant volatiles. Finally, we examined cellular expression profiles of OBP4 in putative antennal sensilla that are related to female A. lineolatus host plant location. The fluorescence in situ hybridization and immunocytochemical labeling assay showed that the OBP4 gene was highly expressed in the multiporous olfactory sensilla medium-long sensilla basiconica rather than in the short sensilla basiconica or uniporous sensilla chaetica. These results, together with those of our previous studies, indicate that OBP4 not only functions in recognition of bug-produced sex pheromones in males, but is probably involved in detection of host plant volatiles in both A. lineolatus sexes. Our findings support the hypothesis that the origin and function of PBPs in hemipteran bugs differ from those of well-known PBPs in lepidopteran moths, which provides a novel perspective on evolutionary mechanisms of sex pheromone communication across insect orders.