Immune Reaction Of American Cockroach, Periplaneta Americana To Metarhizium Anisopliae Isolate CQMa102

American cockroach, Periplaneta americanna is a significant house pest in the world. The hemolymph immune reaction of American cockroach to the entomopathogenic fungus, Metarhizium anisopliae isolate CQMa102, which is broadly used in locust control, was studied in the research. The results will enrich our knowledge about insect immune mechanism and the insecticidal mechanism of entomofungus. They will also be the fundamental work for insecticide development.1. Physical changes of hemolymph of P. americanna after injection with M. anisopliaeThe pH value of hemolymph of P. americanna increased rapidly from pH6.8 to pH 7.0 and the number of hemocytes(NH) of P. americanna at all the developing stages became lower than the blank control(BC) after injection with 4+107/ml fungal spores. The nymphae and ten-day old female adult were more sensitive to the fungal spores than the thirty-day old female adult, and both then- NHs decreased significantly after injection with 4+107 spores/ml. Injection of saline stimulated the increase of NH 2h postinjection(PI) and then declined to the BC.Injected with different doses of spores, the NH of nymphae changed differently. Injection of 4 +107 spores/ml and 4+109 spores/ml caused the significant decrease of the NH 4h postinjection. On the contrary, 4+105 spores/ml injection induced significant increase of the NH.2. Hemolymph immune reaction of P. americanna to the M. anisopliae injectedCell immune is the main reaction of P. americanna to the injected M. anisopliae. The hemocytes approached to the fungal spores 5-10min postinjection and some phagocytosed spores were observed 30min postinjection. At the same time, there appeared lots of nodules composed by numerous hemocytes in the hemolymph of the cockroach. P. americanna elemilated large amount of the fungal spores efficiently by phagocytosing and nodulation and the germinating of the spores was inhibited. These spores disintegrated or menalized finally. The experiment showed that injection of high dose spores destroyed the immune system of the cockroach and the cockroach was easy to be invaded by bacterial pathogens. The higher dose of spores injected,the higher mortality of thecockroach.To be interesting, low dose spores injection strengthened the immune ability of the insect in certain degree and the motaliry of the insect was even lower than that of saline injection control.3 Antimicrobiol substance and protein in the hemolymph of nymphae induced by M. anisopliaeNo antimicrobiol substance was detected in the hemolymph of nymphae by different kinds of micropathogens after injection with M. anisopliae, which meant that the fungus could not induce P. americanna to produce antimicrobiol substance. Injection of fungal spores caused the decline of protein concentration(PC) at the begaining, but after that the PC increased rapidly. The SDS-PAGE electrophoretic patterns of the hemolymph protein showed that the proteins types changed slightly, and only one new protein with 43kDa molecular weitht appeared. However the concentrations of some proteins increased or declined obviously.4 Hemolymph immune reaction of P. americanna after nature infection with M. anisopliaeDripping the cockroach body with M. anisopliae showed that the M. anisopliae spores can invade into the hemolymph coelom of P. americanna through cockroach cuticle and produce blastospores. Some blastspores even can expanded, germinated as time went on. The cockroach restrained the blastospores by phagocytosing and nodulation,and many of them melanized 5d postinfection. The number of hemocytes in the hemolymph of the P. americanna changed slightly and the vital force had no significantly change within one month postinfection with M. anisopliae.