Effects of gibberellic acid (GA3) on hemolymph chemistry and hemocytes of the host Galleria mellonella L. (Lepidoptera:Pyralidae) and parasitoid Pimpla turionellae L. (Hymenoptera:Ichneumonidae)

Stock culture pupal endoparasitiod Pimpla turionellae L. (Hymenoptera: Ichneumonidae) and its host greater wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae) were reared in the laboratory at 25 ± 2 °C, 60 ± 5 % relative humidity, and a photoperiod of 12:12 h. Assays with Gibberellic acid (GA3) were also carried out in the same laboratory condition with stock culture. GA3 dose-related (50 to 5000 ppm) changes in hemolymph proteins and free aminoacids of both host and parasitoid larvae, and the effects of (GA3) on the number, apoptotic and mitotic indices, encapsulation and melanization responses of the host hemocytes were detected. Dose-dependent increases and decreases in proteins and free aminoacids in host and parasitoid larval hemolymph were detected. Total hemocyte counts increased in G. mellonella larvae at all treatment doses whereas GA3 application had not effect on the number of different hemocyte type. While the ratio of necrotic hemocytes increased at all GA3 treatments, that of late apoptotic cells was only higher at doses >200 ppm when compared to untreated larvae. In contrast, a decrease in viable hemocyte indices was observed at the highest dose of 5000 ppm and no difference was observed in early apoptotic indices of larvae at all treatments. The percentage of mitotic index also increased at 5000 ppm. Encapsulation rates of larval hemocytes were dependent on the extent of encapsulation and time but not treatment groups. While the extent of melanization of hemocytes showed differences related to time, in general, a decrease was observed at all doses of GA3 treated larvae at 24 h. The results indicated that GA3 treatment affected host and parasitoid protein profiles involved in endocrinal metabolisms and aminoacids associated with energy metabolisms along with its suppression on the cell immune responses of the host.Key Words:Gibberellic acid, Hemolymph proteins, Free aminoacid, Hemocyte, Apoptosis, Encapsulation