The effect of neomycin on survival and development of Pimpla turionellae L. (Hymenoptera: Ichneumonidae) reared on natural

An aminoglycoside antibiotic neomycin is naturally produced from Streptomyces fradiae bacterium.This antibiotic inhibits protein synthesis at initiation and elongation stages by binding 30 S subunits, sometimes 50S subunits, of ribosomes. In this study, Galleria mellonella pupae reared on artificial diet containing neomycin will be used as natural host for Pimpla turionellae in experimental groups. In these groups, first instar larvae of G. mellonella will be reared on artificial diets containing 0.005, 0.01 or 0,5 g (g/100 gr of diet) until 7th instar larvae, the pupae from these larvae will be used as host for rearing P. turionellae. In control group, the pupae from larvae reared on artificial diets without neomycin will be used as host. As bioindicators of long-term physiological stress responses, survivorship of 7th-instar larvae, pupation and adult emergence rate and developmental time to these stages of endoparasitoid P. turionellae were determined by rearing the parasitoid on a factitious host, G. mellonella pupae treated with neomycin. Survivorship in 5th-instar, pupal and adult stages of P. turionellae reared on G. mellonella pupae as host fed with different concentrations of neomycin were significantly decreased in comparison to control group. While 86.6 % of P. turionellae larvae reared on host pupae ascontrol group reached 5th-instar stage, the larvae reared on host pupae exposed with 0.005 and 0.01 % of neomisin reached 5th-instar stage by 31.6 and 28.2% respectively. A 79.9 % of P. turionellae pupae were produced from host pupae exposed to diets without neomycin while other neomycin concentrations significantly decreased pupation rate of this parasitoid by 50%. In comparison to control group, neomycin at 0.01 % significantly decreased pupation rate of P. turionellae to 23%. The host pupae reared on diets without neomycin produced 78.3 % of P. turionellae adults. However, adult emergence rate from hosts exposed to other neomycin concentrations was significantly decreased by a rate of 1/3 or above. Neomycin significantly shortened developmental time to reach 5th-instar of P. turionellae while this antibiotic had no significant effects on post larval developmental stages. The highest concentrations of neomycin (0.5 %) significantly shortened developmental time to 5th instar by approximately 2 days. P. turionellae larvae reared on control host pupae reached 5th instar by about 9.6 days, while the larvae reared from host pupae exposed to highest antibiotic concentration completed their development to 5th instar by about 7.4 days. These results showed that neomycin, and possibly its metabolites, contaminated P. turionella larvae from host and affected mostly larval stages of the parasitoid.