Ning Lv,Lei Wang,Wen Sang,Chang-Zhong Liu,Bao-Li Qiu
Pea aphid (Acyrthosiphon pisum) is a worldwide pest that feeds exclusively on the phloem sap of numerous host plants. It harbours a well-known primary endosymbiontBuchneraaphidicolathat helps to overcome the nutritional deficiency of a plant-based diet. However, how theBuchneracontributes to the nutritional and energy metabolism of its aphid host is unclear to date. In the current study, the function ofBuchnerain relation to nutritional synthesis of pea aphid was investigated by disrupting the primary endosymbiont with an antibiotic rifampicin. Our findings revealed that the disruption ofBuchneraled to infertility and higher loss in body mass of aphid hosts. Body length and width were also decreased significantly compared to healthy aphids. The detection of nutrition indicated that the quantity of proteins, soluble sugars, and glycogen in aposymbiotic pea aphids increased slowly with the growth of the aphid host. In comparison, the quantities of all the nutritional factors were significantly lower than those of symbiotic pea aphids, while the quantity of total lipid and neutral fat in aposymbiotic pea aphids were distinctly higher than those of symbiotic ones. Thus, we concluded that the significant reduction of the total amount of proteins, soluble sugars, and glycogen and the significant increase of neutral fats in aposymbiotic pea aphids were due to the disruption ofBuchnera, which confirmed that the function ofBuchnerais irreplaceable in the pea aphid.Keywords:Buchnera;pea aphid;endosymbiont;antibiotics;nutrition
Management of the rice brown planthopper Nilaparvata lugens Stål is challenging because it can rapidly adapt to new pesticides within several generations. Combined use of chemical insecticides and antimicrobials was proposed as an alternative strategy to control N. lugens. Our previous experiments identified two effective agents (chemical insecticide: pymetrozine and antimicrobial: zhongshengmycin) that act on different targets in N. lugens. However, conditions and effectiveness of combinations of antimicrobials and insecticides against N. lugens are still unknown. Here, we evaluated separate and combined effects of pymetrozine and zhongshengmycin on third instar nymphs of N. lugens under laboratory and greenhouse conditions. Results showed that zhongshengmycin exerts significant inhibitory effects on the three endosymbionts Pichia guilliermondii, Cryptococcus peneaus, and Pichia anomala cultured in vitro of N. lugens. Combinations of pymetrozine and zhongshengmycin under laboratory conditions produced additive or synergistic effects on N. lugens and caused higher mortality in third instar nymphs than either of them used alone. Experiments under greenhouse conditions further demonstrated that effective component quality ratio of pymetrozine to zhongshengmycin of 1:10 and 1:40 with co-toxicity coefficients of 221.63 and 672.87, respectively, also produced significant synergistic effects against N. lugens. Our results indicated that chemical insecticides combined with antimicrobials may provide a potential novel strategy for controlling N. lugens by inhibiting its endosymbionts.
危险品化学品经营许可证（带存储）