The Effect Of Imidacloprid On Chemical Elements In Rice Plant And Brown Planthopper, Nilaparvata Lugens (St(?)l)

This study investigated the effect of imidacloprid on chemical elements in rice plants and the conductance of these elements via rice plants between rice-N. lugens system and the changes of chemical elements in N. lugens (macropterous and brochypterous, male and female, adult and nymph) following foliar spray of different doses of imidacloprid.1. Imidacloprid-induced cascade effect on some chemical elements in rice plants and the brown planthopper Nilaparvata lugens (Hemiptera: Delphacidae)The wide-spread use of imidacloprid against insect pests has not only increased the rate of the development of target pest resistance but also resulted in various negative effects on crop plants and Nilaparvata lugens resurgence. However, the mechanisms are poorly understood, as with the effect of imidacloprid on chemical elements in rice plants and the conductance of these element changes via rice plants between rice-N. lugens system. The present study investigated changes of Cu, Fe, Mn, Zn, Ca, K, Mg and Na contents in rice plants following imidacloprid foliar spray, in the adult female of N.lugens developed from feeding on treated plants and honeydew of the female. The results showed that imidacloprid foliar spray significantly increased Fe and K concentrations in the leaf sheath while there was little influence on Mn. Generally, Fe, Mn K and Na concentrations in the leaf blade were noticeably decreased but Ca concentrations in the leaf blade for 10 and 30 ppm imidacloprid treatments were significantly increased. Contents of most elements except K and Mg in the adult female body and honeydew were significantly elevated. Multivariate analysis showed that Fe, Mn and Na in the leaf blade, and Fe and Mn in the leaf sheath had direct conductance, i.e., elements which increased in leaf blade or leaf sheath were higher in the adult female body. The relationship between most elements in the adult female body and in the honeydew showed a positive correlation coefficient. In addition, imidacloprid application methods had significant effects on contents of most elements in adult female body and in honeydew. The contents of Fe, Mn, Zn and Ca in adult female body after imidacloprid foliar spray were significantly higher than those for imidacloprid vial test, indicating that the effect of imidacloprid foliar spray on element contents in N.lugens adult female body was amplified via rice plants. Contents of Cu, K, Mg and Na were not influenced by application methods except Cu for 60 ppm imidacloprid and Na for 30 ppm imidacloprid.2. The effect of imidacloprid on chemical elements on N. lugens (macropterous and brochypterous, male and female, adult and nymph)This study investigated changes of chemical elements in N. lugens (macropterous and brochypterous, male and female, adult and nymph) following foliar spray of different doses of imidacloprid. The results are as follows:Imidacloprid influenced Fe contents in macropterous and brachypterous adults significantly. Multiple comparisons showed that Fe and Ca contents in macropterous adults were significantly higher than those in brachypterous adults, in contrast, K content was significantly lower than brachypterous adults. Fe and Ca contents in both macropterous and brachypterous adults developed from feeding on rice plants treated with 10 and 30 ppm imidacloprid, and Fe content in both macropterous and brachypterous adults from feeding on rice plants treated with 60 ppm imidacloprid were significantly lower than those on control plants. Interaction effects between imidacloprid concentrations and sex of N. lugens (female and male) affected Mn and Zn contents in N. lugens significantly. Multiple comparisons showed that Fe, Mn, Zn, Ca and Na contents in adult females were significantly lower than those in adult males. While there were no significant differences on Cu, K and Mg between female and male. Fe, Mn and Ca contents in female and male adults developed from feeding on the rice plants treated with 10 ppm imidacloprid were significantly lower than those on control plants. In addition, Fe and Ca contents in female and male adults on rice plants from 30 and 60 ppm imidacloprid sprays were significantly lower than those on control plants. Multiple comparisons showed that Cu, Fe, Zn and Ca contents in N. lugens adults were significantly higher than those in nymphs. Fe and Ca contents in nymphs feeding on rice plants treated with 10, 30 and 60 ppm imidacloprid were significantly higher than those on control plants. Times of imidacloprid application significantly affected Fe, Mn and Na contents in macropterous adults and Fe, Mn, Zn and Ca contents in brachypterous adults. Multiple comparisons showed that Mn content in both macropterous and brachypterous adults increased with increase of application tmies of imidacloprid. In contrast, Fe content decreased with increase of application times. In addition, imidacloprid induced decrease of Fe and Ca contents in N. lugens.