Biology of Ichneumon promissorius (Ichneumonidae), an exotic pupal parasitoid of Helicoverpa zea (Noctuidae)

Ichneumon promissorius is a potential biological control agent of the bollworm, Helicoverpa zea. The parasitoid must cope with environmental situations such as lack of adult food and absence of suitable hosts in order to successfully colonize. The effects of diet and host availability on longevity and fecundity of the parasitoid were determined in the laboratory. With honey, longevity significantly increased by 15.7 and 21 days for females and males, respectively. Honey significantly increased fecundity. A delay in host availability of 10 days significantly increased female longevity but reduced fecundity. Results indicated that I. promissorius would benefit from the presence of carbohydrate sources in the field and that some reduction in fecundity will occur if hosts are not available within the first 10 days of adult life.; I. promissorius ability to locate and access the subterranean pupal cell of its host is vital for successful colonization. Behavioral mechanics by which it accesses the pupal hosts and an assay for retention of host searching behaviors are described. Parasitoid females access concealed hosts by digging into the emergence tunnel created by the host larvae prior to pupation. There was no significant change in percent parasitism of concealed hosts over 3 years of laboratory rearing (ca. 76.4%). There was no significant difference in percent parasitism of concealed hosts among ages 1-4 days old, 5-8 days old or 9-12 days old or between experienced and naive females. Results provide a description of I. promissorius host finding behaviors and indicate that the rearing program was producing females capable of locating hosts in the environment.; Aspects of I. promissorius reproductive biology were also examined. Mating behavior was typical of the Ichneumonidae. Females mated only once, and old virgins were as receptive and attractive to males as young ones. Some mated females lacked sperm in their spermathecae, indicating a failure of insemination during copulation. Oviposition is described, as well as movements by the female which indicated fertilization of the egg as it was deposited (primary sex ratio). Prediction of male offspring was 95% accurate, prediction of female offspring was 67% accurate. Egg load was not correlated with body size, but was influenced by degree of exposure to hosts.; Superparasitism and host discrimination were studied by use of a wildtype strain and a mutant strain. I. promissorius readily superparasitizes in the laboratory and is a poor discriminator. This may be due to artificial selection, presence of conspecifics prior to experiments or possibly natural selection.