Developmental interactions between the tobacco hornworm manduca sexta and its braconid parasite apanteles congregatus¹
1978
Beckage, N. E. (Nancy E.) | Riddiford, L. M. (Lynn M.)
After newly hatched Manduca sexta larvae were parasitized by Apanteles congregatus, the wasps emerged from third, fourth, fifth, or supernumerary sixth stage host larvae. The number of parasites present within a host determined the time required for Apanteles development and the final host instar. In addition, the percent of parasites within a host which successfully completed their development and emerged was determined by the parasite load. Parasitized larvae gained weight more slowly and attained lower final weights than did unparasitized control larvae; this was attributed to reduced food consumption by the parasitized larvae. Following parasitization of freshly ecdysed fifth-instar Manduca larvae, the rate of Apanteles development was accelerated with respect to that observed when young larvae served as hosts. Parasitism also induced developmental changes in Manduca larvae which encapsulated Apanteles and from which no parasites emerged. Our findings suggest that such larvae retain high juvenile titers late in larval life, preventing normal metamorphosis.
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