Effects of the entomopathogenic nematode, Heterorhabditis bacteriophora HP 88 and azadirachtin on the immune defence response and prophenoloxidase of Parasarcophaga surcoufi larvae (Diptera: Sarcophagidae).
Each third larval instar (155-175 mg) of the fleshfly, Parasarcophaga surcoufi was injected with 20 and 40 infective juveniles (IJs) of entomopathogenic nematode, Heterorhabditis bacteriophora, and with 0.5 and 1 microg of azadirachtin. Injection with 20 IJs decreased the total haemocyte count (THC) up to 40 h post-injection, except for its increase at 20 h. On the contrary, injection with 40 IJs increased the THC during the hours post-injection, except for its decrease at 40 h. The injection of nematode (40 IJs) decreased, the percentage of differential haemocyte count of P. surcoufi larvae, specially the granulocytes and plasmatocytes at 40 h. Whereas, prohaemocytes and oenocytoids were increased at 40 h post-infection. The granulocytes and plasmatocytes were engaged with encapsulation of the nematode, H. bacteriophora. The released symbiotic bacterium, Xenorhabdus luminescens was poorly phagocytosed by the granulocytes. After injection of the larvae with azadirachtin, THC and the percentage of the number of oenocytoids were particularly increased after 40 h of injection with azadirachtin; plasmatocytes and granulocytes were decreased at 10 h post-injection with 0.5 microg and at 40 h post-injection with 1 microg of azadirachtin. The most prominent haemocyte deformities in P. surcoufi larvae treated with azadirachtin were the release of cytoplasmic components from granulocytes together with bulging or lysis of plasmatocytes. Maximal haemolymph phenoloxidase (PO) activity was obtained at pH 6.2 and 6.6. This activity increased with increasing the pre-incubation time using laminarin, alpha-chymotrypsin and trypsin as activators. Injection of both nematode and azadirachtin significantly suppressed the haemolymph PO activity even in the presence of the activators laminarin, alpha-chymotrypsin and methanol. This suppression was dose-dependent and reached maximum at 30 h post-injection. The electrophoretic haemolymph protein profile was time-dependent as indicated by appearance and disappearance of protein bands. After 40 h post-injection with the nematode all the protein bands were replaced by new ones (probably containing immune protein). However, at this time injection with azadirachtin (1 microg) lead to appearance of 10 new protein bands & disappearance of an equal number of the present band.
Ayaad
T H
TH
Department of Entomology, Faculty of Science, Cairo University, Egypt.
Dorrah
M A
MA
Shaurub
el-S H
el-SH
el-Sadawy
H A
HA
D000818:Animals; D004156:Catechol Oxidase / Q000378:metabolism*; D002452:Cell Count; D004175:Diptera / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology* / Q000469:parasitology; D004792:Enzyme Precursors / Q000378:metabolism*; D006434:Hemocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology; D007814:Larva / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology* / Q000469:parasitology; D036701:Limonins / Q000494:pharmacology*; D009348:Nematoda / Q000276:immunology / Q000502:physiology*; D010572:Pest Control, Biological; D013997:Time Factors
D004792:Enzyme Precursors; D036701:Limonins; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; C010329:azadirachtin