Studies On The Behaviour Of Entomopathogenic Nematodes And The Hemolymph Pathology Of Galleria Mellonella Larvae Infected With Entomopathogenic Nematodes

In this paper, 5 species entomopathogenic nematodes come from abroad were tested. The aim of the research was to investigate the effects of biotic factors (Galleria mellonella and tomato roots) on the behaviors of entomopathogenic nematodes and the effects of entomopathogenic nematodes on energetic contents in hemolymph of Galleria mellonella.Vertical and horizontal dispersal ability and host-searching behavior of 5 species entomopathogenic nematodes in the presence of insect hosts and plant roots/germinating seeds, offered individually and in combination, was studied using a Y-tube filled with sand (8% w/w) and water-agar (2%) plate. The presence of a host insect enhanced the dispersal of nematodes. Seven hours after treatment Us (Sg, Hb) responded positively to host cues from Galleria mellonella but poorly to cues from tomato germinating seeds in agar plates. In both experiments on vertical/horizontal dispersal and host-searching ability, Hb, Hm and Sg tested in absence of a host moved randomly. However, when an insect host was added to the agar plates or Y-tube a difference in dispersal patterns could be observed. In agar plates and Y-tube Hb, Hm and Sg responded positively to the presence of Gm, to tomato roots or germinating seeds and to Gm larvae in direct contact with roots/germinating seeds of tomato. Furthermore, Hb, Hm and Sg reacted better to larvae damaged tomato roots than to mechanically damaged ones. Those above showed that Hb> Hm and Sg were cruising nematodes. Whereas, Sc and Sf always had more than 72% nematodes remaining in the inoculation point whether the host and/or roots exist or not. This showed that Sc and Sf were ambushing nematodes. IJs responded strongly to the combination of plant roots and feeding larvae indicating that the tritrophic interaction formed by IJs-Gm-tomato plant might be an infochemical-mediated interaction.Another part presented the effects of 5 species of entomopathogenic nematodes(Heterorhabditis spp. and Steinernema spp.) on the energetic contents in hemolymph of Galleria mellonella. In all the species the number of hemocytes decreased by over 85% and hemocyte shape was obviously changed 24 hours after treatment. The total volume of hemolymph of 5th larvae infected with nematodes decreased by 73.62%, while esterase activity and content of protein increased. The decrease rate of total carbohydrate content was 14%~70%. The symbiotic bacteria were found in the hemolyph of G mellonella larvae 16h after infection with entomopathogenic nematodes and multiplied rapidly in 48h. Results of this study revealed that the entomopathogenic nematodes destroyed the host immune system and dramatically changed the content of energy source in the hemolymph of the host.