| Bemisia tabaci is one of the most important pests worldwide, and it can cause greatdamage by direct feeding and virus transmission in agricultural and horticultural cropproduction. Chemical control is an important part of the integrated management program ofthis pest. Imidacloprid is a kind of systemic insecticides, belongs to neonicotinoids that hasmuch lower toxicity to mammals and broad insecticidal spectrum, especially for the suckingpests.“Root Feed” is a proprietary crop health product that was formulated to improve cropproductivity and enhance insect resistance.Imidacloprid (0,3,6, or12mg per plant）and Root Feed (0,0.02,0.04, or0.08ml perplant) were combined randomly and applied by dripping them to the growth medium. Themortalities of adult and nymph of B. tabaci, the population dynamic in field and greenhouse,and in consider of the effect on plant growth were compared to determine the optimalconcentrations and their combination. Thereafter the imidacloprid distribution and theirinfluence on different development stage of B. tabaci under this combination, on the stratafrom up, middle, and bottom were compared.1.Optimal combination of “Root Feed” and Imidacloprid.“Root Feed” has no obviousefficiency against B. tabaci, the mortalities of adult and nymph were not significantly differedwith control, and the efficiency was imidacloprid concentration dependent, the lowconcentration (3mg per plant) could only be effective against B. tabaci for a short period ofabout20days, and the combination which contain12mg could cause the adult mortalityabove60%and nymphal mortality above80%in all sampling period. The active ingredientwas also imidacloprid concentration dependent and gradually decreased from10DAT to50DAT (Days after treatment), and rapidly decreased from75.82mg/kg to17.93mg/kg at20DAT.More active ingredient was detected under the combination of12/0.02(mg/ml), andcaused the highest mortalities of adult and nymph, and the adult population after treatmentwas lowest under field and greenhouse condition from30DAT to50DAT. This combinationcould improve the plant growth and lead to the highest dry weight of whole plant after20 DAT, and could effectively manage B. tabaci for up to50days under field and greenhousecondition.2. Imidacloprid transferring and influence on the development of B. tabaci. Imidaclopridwas mainly concentrated on the stratum of bottom, and caused the highest adult mortality andnymphal hatch rate, and the lowest egg number; the survival of nymph and pupa were mostnegatively affected on up stratum. |
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