Search for a sensitive stage for aposymbiosis induction in Culex pipiens pipiens by antibiotic treatment of immature stages

Abstract

The elimination of symbiotic Wolbachia pipientis from Culex pipiens pipiens was studied by exposing the larvae or pupae to chlortetracycline hydrochloride for different lengths of time and for different stages in the life cycle. The effect of the antibiotic was cumulative. The longer the immature stages were treated, the poorer was the hatching rate of their eggs when they became adults. Larvae reared in antibiotic from the beginning of first, second, or third instar developed into adults with 100% hatching failure. If the insects were reared in the antibiotic from the beginning of the fourth instar only, about one-third of their eggs hatched. Rearing the immatures in antibiotic for single instars demonstrated that the ultimate deleterious effects were essentially the same for all stages, indicating that there is no uniquely sensitive stage for destroying the rickettsia. Many of the unhatched eggs contained fully developed, but dead, embryos.