Effects of insect diapause and parasitization of a braconid, Bracon brevicornis Wesm. on the haemolymph of its host Sesamia cretica Led.
Eight types of haemocytes were defined in the 6th instar larvae of the greater sugar cane borer Sesamia cretica Led, as follows prohaemocytes, plasmatocytes, granular cells, spindle cells, adipohaemocytes, oenocytoids, spherule cells and cystocytes. Total haemocyte counts (THCs) and differential counts (DHCs) were estimated for diapausing and non-diapausing larvae. During diapause, there was a significant reduction in the numbers of all haemocyte types. Upon termination of diapause, the haemocyte level increased. This reduction in the haemocyte level observed during diapause may be due to the decreased in the metabolic activity. Also, a decrease in the total haemocyte counts appeared after the parasitization of 6th instar S. cretica larvae by the 2nd larval instar of braconid ectoparasioid Bracon brevicornis Wesm. (Hymenoptera: Braconidae) as compared to the unparasitized ones. However, the DHCs in parasitized larvae showed an increase in the number of phagocytic cells (plasmatocytes, granular cells and spindle cells) and a remarkable decrease in the prohaemocyte counts was detected as compared to that of the unparasitized ones. Moreover, teratocytes appeared in the blood smears of paraitized S. cretica by B. brevicornis. They were round to oval, opaque and stain dark with Giemsa stain and ranged between 5-30 mu in diameter.
el-Mandarawy
M B
MB
Biological Control Department, Plant Protection Research Institute, A.R.C., Dokki, Giza, Egypt.
D000818:Animals; D006434:Hemocytes / Q000145:classification / Q000502:physiology; D006458:Hemolymph; D006790:Host-Parasite Interactions; D006927:Hymenoptera / Q000502:physiology*; D007814:Larva; D009036:Moths / Q000469:parasitology* / Q000502:physiology*