Long-Term Prophylactic Antibiotic Treatment: Effects on Survival, Immunocompetence and Reproduction Success ofParasemia plantaginis(Lepidoptera: Erebidae)

Abstract

Hundreds of insect species are nowadays reared under laboratory conditions. Rearing of insects always implicates the risk of diseases, among which microbial infections are the most frequent and difficult problems. Although there are effective prophylactic treatments, the side effects of applied antibiotics are not well understood. We examined the effect of prophylactic antibiotic treatment on the overwintering success of wood tiger moth (Parasemia plantaginis) larvae, and the postdiapause effect on their life-history traits. Four weeks before hibernation larvae were treated with a widely used antibiotic (fumagillin). We monitored moths’ survival and life-history traits during the following 10 mo, and compared them to those of untreated control larvae. Prophylactic antibiotic treatment had no effect on survival but we show effects on some life-history traits by decreasing the developmental time of treated larvae. However, we also revealed relevant negative effects, as antibiotic treated individuals show a decreased number of laid eggs and also furthermore a suppressed immunocompetence. These results implicate, that a prophylactic medication can also lead to negative effects on life-history traits and reproductive success, which should be seriously taken in consideration when applying a prophylactic treatment to laboratory reared insect populations.

Antibiotics accelerate growth at the expense of immunity

“…While the control larvae took longer to develop, once they reached adulthood, the emerging females were significantly heavier than the antibiotic-treated group ( figure 4 b ). This is congruent with previous findings where antibiotics were fed to pre-diapausing larvae of the wood tiger moth [ 67 ]. It is commonly accepted that heavier weight translates into greater fecundity [ 81 ], as was shown by Dickel et al [ 67 ], where heavier control females laid more eggs than females that had been feed with antibiotics.…”

“…However, lytic and PO did not differ from the E. coli priming. By contrast, [ 67 ] reported a high PO activity in larvae that have been fed an antimycotic (fumagillin). [ 68 ] simulated ectoparasitism by implanting nylon threads on larvae and measured the encapsulation response (i.e.…”

Evaluating responses to temperature during pre-metamorphosis and carry-over effects at post-metamorphosis in the wood tiger moth (Arctia plantaginis)

“…reproductive output) due to rate-limiting resources. It has been shown that smaller wood tiger moth females produce less eggs compared to larger ones [73]. This carried-over effect could have negative consequences to the adult phenotype via an underrepresentation of their genotype in the reproductive cohort and/or if the genotypes have reduced fitness compared to those from larger females.…”

Sustainable farming of the mealworm Tenebrio molitor for the production of food and feed

“…Furthermore, sterile mealworms perform poorly, suggesting that the microbiota is required for the efficient digestion and detoxification of plant secondary products [76]. In other insects, antibiotic use can shorten the development time as well as reduce the number of eggs [77][78][79]. Although the treatment of edible insects with antibiotics could solve some of the problems discussed previously, the benefits are outweighed by the negative side effects in addition to the known problem of increasing the spread of antibiotic-resistant pathogens.…”