Novel roles for the corpus allatum hormone in the cost of sexual interactions in the linden bug Pyrrhocoris apterus

The cost of sexual interactions, usually expressed as a reduction of life-span, is a fundamental but poorly understood aspect of life. According to a widely accepted view, a rise in the “pro-aging” juvenile hormone (JH) might contribute to the decrease of life span caused by sexual interactions. We tested this hypothesis using the linden bug Pyrrhocoris apterus by removing the corpus allatum (CA), the source of JH. If JH is causally involved in the cost of sexual interactions, then the absence of CA (JH) should decrease the negative effect of sexual interactions on survival. As expected, ablating the CA significantly prolonged life-span of both virgin females and virgin males. Mated insects of both sexes lived significantly shorter than virgins. However, contrary to prediction, the decrease of life span by sexual interactions was similar in control and CA-ablated males, and was even enhanced in CA-ablated females. Another unexpected finding was that males paired with CA-ablated females lived almost as long as virgin males and significantly longer than did males paired with control females, although ablating the female CA did not cause any decrease in mating activity. On the other hand, females paired with CA-ablated males lived only slightly longer than did females paired with control males. These results highlight several important points. (1) In both genders, the negative effect of sexual interactions on insect's survival is not mediated by the insect's own CA. (2) The male CA has only minor effect on female survival, while (3) the female CA (JH) is principally responsible for the sex-induced reduction in the male survival.     

Morphological effects of juvenile hormone mimics on embryonic development in the bug,Pyrrhocoris apterus

Summary Embryos ofPyrrhocoris apterus exposed to juvenile hormone mimics (JH) were examined throughout development to determine the progressive effects of treatment. Prior to blastokinesis whole experimental embryos did not differ morphologically from control embryos fixed at the same stage. Treated embryos failed to complete blastokinesis due to abnormal breakage of the extra-embryonic membranes.In the embryo-larva transition, JH exposure interfered with dorsal closure, with the consolidation of the nerve cord, and with the extension of appendages. Yet pigmentation and muscle differentiation occurred.These effects were interpreted and discussed with reference to the role of juvenile hormone in post-embryonic development.This is a portion of a dissertation submitted to the graduate school of Harvard University, in partial fulfillment of the requirements for the degree of Doctor of Philosophy (1973). It was previously reported in abstract (Enslee and Riddiford, 1970). This research was supported by NIGMS Training Grant T01 GM 00036-09, 11, 12, 13 to E.C.E. and NSF grants GB 6730, GB 7966 to L.M.R.