Quantitative and Qualitative Impacts of Selected Arthropod Venoms on the Larval Haemogram of the Greater Wax Moth, Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae)

Abstract

The greater wax moth, Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae) is the most destructive pest of honey bee, Apis mellifera Linnaeus (Hymenoptera: Apidae), throughout the world. The present study was conducted to determine the quantitative and qualitative impairing effects of the arthropod venoms, viz., death stalker scorpion Leiurus quinquestriatus (Hemprich & Ehrenberg) venom (SV), oriental Hornet (wasp) Vespa orientalis Linnaeus venom (WV) and Apitoxin of A. mellifera (AP) on the larval haemogram. For this purpose, the 3rd instar larvae were treated with LC50 of each of these venoms (3428.9, 2412.6, and 956.16 ppm, respectively). The haematological investigation was conducted in haemolymph of the 5th and 7th (last) instar larvae. The important results could be summarized as follows. Five basic types of the freely circulating haemocytes in the haemolymph of last instar (7th) larvae of G. mellonella had been identified: Prohemocytes (PRs), Plasmatocytes (PLs), Granulocytes (GRs), Spherulocytes (SPs) and Oenocytoids (OEs). All venoms unexceptionally prohibited the larvae to produce normal hemocyte population (count). No certain trend of disturbance in the differential hemocyte counts of circulating hemocytes in larvae of G. mellonella after treatment with the arthropod venoms. Increasing or decreasing population of the circulating hemocytes seemed to depend on the potency of the venom, hemocyte type and the larval instar.  In PRs of last instar larvae, some cytopathological features had been observed after treatment with AP or WV, but SV failed to cause cytopathological features. With regard to PLs, some cytopathological features had been observed after treatment with AP while both SV and WV failed to cause cytopathological features in this hemocyte type. No venom exhibited cytopathological effects on GRs, SPs or OEs.