Vitellin and vitellogenin in the soldier bug, Podisus maculiventris: identification with monoclonal antibodies and reproductive response to diet.

A 171,000 M(r )polypeptide of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) that constituted 16% of the protein in eggs also constituted up to 25% of the protein in hemolymph of fed females. It was identified as the major or sole apoprotein of vitellogenin. Eggs contained major polypeptides of 171, 106, and 51 kDa. The hemolymph polypeptide was identified with a polypeptide (vitellin) in egg extracts by comparing molecular weights, specificity of occurrence in fed females, and immunological reactivities. Females, starved for 5 days after eclosion to assure complete previtellogenic development, produced vitellogenin within a day after feeding on larval Galleria mellonella, and within 4 days after feeding on an artificial diet. Appearance of vitellogenin preceded ovarian growth by 2-3 days. Two monoclonal antibodies raised against egg proteins of P. maculiventris were selected for their strong reaction against egg extract and female hemolymph and null reaction against male hemolymph. Only one 170-kDa band in egg and hemolymph reacted with the antibodies on denaturing Western blots. These monoclonal antibodies are being used to develop an enzyme-linked immunosorbent assay (ELISA) to quantitate reproductive response of females to diets of differing quality.

Ecdysteroid levels/profiles of the parasitoid wasp, Diapetimorpha introita, reared on its host, Spodoptera frugiperda and on an artificial diet.

Diapetimorpha introita is an ichneumonid ectoparasitoid of the fall armyworm, Spodoptera frugiperda. Since it has been reported that D. introita wasps reared on an artificial diet exhibit a significantly lower percentage of adult eclosion and fecundity than host-reared wasps, this study was undertaken to elucidate the factors responsible for the reduced viability observed in diet-reared wasps. A system of markers has been devised to track the development (from the initiation of cocooning through adult eclosion) of D. introita. Although wasps reared on artificial diet developed more slowly than did those reared on host pupae, both diet- and host-reared wasps passed through the same stages of development - the eyes enlarged and moved backward, the gut was purged and upon ecdysis the exarate pupa emerged. The thorax was the first to darken, followed by the head and then the abdomen. Pharate pupal formation occurred before gut purge. Two peaks of hemolymph ecdysteroids were observed, one in wasps in which gut purge was almost complete and the second in day-2 exarate pupae. Ecdysone and 20-hydroxyecdysone were the major ecdysteroids present in hemolymph sampled at these times. Small quantities of 20,26-dihydroxyecdysone, polar ecdysteroids and/or possibly 26-hydroxyecdysone were also present. In six stages of development, hemolymph ecdysteroid titers were significantly higher in host-reared than in diet-reared wasps (Eye 1, Eye 2, Gut Purge 2, Pharate Pupa, Head/Thorax Dark, and Abdomen Dark). Relatively high percentages of mortality were observed in diet-reared wasps in four of these stages and in two others which occurred in close proximity to one of the stages, the Abdomen Dark stage. Thus, insufficient ecdysteroid in the hemolymph may be responsible, in part, for the relatively high percentage of mortality that occurred in wasps reared on an artificial diet.