Insects often face both conditions with sufficient nutrients and conditions of undernutrition in the field. Through gustatory receptors, insects sense nutrients and regulate their physiological functions such as feeding and reproduction. However, it remains unclear whether signaling pathways activated by gustatory receptors depend on the concentration of nutrients and whether the difference in signaling pathways directly affects insects’ physiological functions. Herein, we found that a sugar gustatory receptor, NlGr11, from the brown planthopper (BPH), Nilaparvata lugens, activated G protein‐coupled signaling and ionotropic pathways when bound to high galactose concentration. BPHs subsequently demonstrated longer feeding times, feeding loads, and higher vitellogenin (NlVg) expression than BPHs exposed to high galactose concentrations, which only activated the ionotropic pathway. For the first time, our findings link plant nutrient conditions, signaling pathways activated by nutrients, and their gustatory receptors, and nutrient dose‐dependent feeding efficacy and vitellogenin (Vg) expression in an insect. This will help us to better understand the molecular mechanism for insect feeding strategies on plants at different stages of nutritional conditions.

BACKGROUND RNA interference (RNAi) technology is an environmentally friendly strategy for controlling insect pests. Lipopolysaccharide‐binding protein (LBP) recognizes lipopolysaccharides, which are a major outer membrane constituent of Gram‐negative bacteria. We propose that the LBP gene is a potential target for termite management; however, to date, no studies have examined this gene in termites. RESULTS In this study, we cloned the LBP gene of Coptotermes formosanus (Cf) and found that the mortality rate of termite workers significantly increased, and the repellence of these workers to Gram‐negative bacteria was suppressed after knockdown of CfLBP using double‐stranded RNA (dsRNA) injection and feeding. Moreover, the mortality rate of termite workers fed with CfLBP dsRNA and three Gram‐negative bacteria (provided separately) was over 50%, which was much higher than that of termites treated with either CfLBP dsRNA or Gram‐negative bacteria. Finally, we found that CfLBP impacts the IMD pathway to regulate the immune response of C. formosanus to Gram‐negative bacteria. CONCLUSION CfLBP plays a important role in the immune defense of termites against Gram‐negative bacteria. It can be used as an immunosuppressant for RNAi‐based termite management and is an ideal target for termite control based on the combined use of RNAi and pathogenic bacteria. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

No abstract

Population density modulates insect progenitive plasticity through the regulation of dopamine biosynthesis

No abstract