Sublethal Effect Of Hexaflumuron On Insect Immunity And The High-throughput Screening Of Pesticides Acting On Hemocyte Immune

Insect immunity is an important safety barrier by which insect adapt to the complex living environment, maintain and stable internal environment. Despite of the large number of literature about insect cellular immune responses have been reported, but the biological and chemical information of interference and regulation of the insect immune system is still limited. This paper intended to explore interference mechanisms on insect immunity and physiological effects of insect growth and development of sublethal hexaflumuron, to provide preliminary experimental evidence for clarify the correlation of insect immune defense capacity changes and the survival fitness. Meanwhile, based on insect hemocyte research, the high-throughput screening of immune drug was established to provided for the screening platform for targeting drug development.The results showed that sublethal hexaflumuron caused Spodoptera litura Life duration prolonged, body weight and body length decreased.After treatment with sublethal hexflumuron, the granlocyte (GR) of swelled, the total hemocyte count (THC) was dose dependently decreased but the different types of blood cells (DHC) of was not obviously change in Mythimna separata; the proportion of plasmatocyte (PL) of significantly increased, the proportion granulocyte (GR) significantly decreased, the hemolymph total carbohydrate and trehalose content increased, the level of trehalose was increased about 6.0 times, and the glyceride content was also interfered in S. litura.In vitro and in vivo, the phenol oxidase (PO) in M. separata was slightly activated by sublethal hexaflumuron, and the PO activity in plasma increased about 2.8 times treated with 0.5mg/L hexaflumuron. The nitric oxide synthase (NOS) was present in M. separata hemocyte with NADPH-diaphorase reduction method and the NOS activity was induced by LPS and Sephadex G-100. In vitro and in vivo. the NOS activity in M.separata was activated at low concentrations hexaflumuron (0.1mg/L), but dose-dependent decreased with the hexaflumuron concentration incresed.The immune drug screening experiments showed that hemocytes of M. separata was in good condition, had specific morphology and spreading behavior, and still has the function of immune phagocytosis of yeast and bacteria in insect medium(TNM-FH) containing 62.5μg/L phenyl-thiourea. Different solvents such as DMSO, DMF, acetone did not affect the morphology and structure of hemocyte when the concentration was no more than 0.1%. Researching 9 pesticides commercialized, chlorpyrifos had a significant cytotoxicity on hemocytes of M.separata, made the granule increased in hemocytes and some hemocytes were apoptotic status. Screening of 33 new compounds, two of furan chalcones changed the M. separata plasmatocyte morphology and spreading behavior. In this research, no compounds that inhibit phagocytosis were found.