Effects of egg load on the host-selection behaviour of Helicoverpa armigera (Hubner) (Lepidoptera : Noctuidae)

We examined the effect of age-specific fecundity, mated status, and egg load on host-plant selection, by Helicoverpa armigera under laboratory conditions. The physiological state of a female moth (number of mature eggs produced) greatly influences her host-plant specificity and propensity to oviposit (oviposition motivation). Female moths were less discriminating against cowpea (a low-ranked host) relative to maize (a high-ranked host) as egg load increased. Similarly, increased egg load led to a greater propensity to oviposit on both cowpea and maize. Distribution of oviposition with age of mated females peaked shortly after mating and declined steadily thereafter until death. Most mated females (88%) carried only a single spermatophore, a few females (12%) contained two. The significance of these findings in relation to host-plant selection by H. armigera, and its management, are discussed

Reactions of the different breeding season corns as a function of injury of cotton bollworm (Helicoverpa armigera Hbn.).

The aim of present investigations was the increasing of knowledge of the cotton bollworm’s ( Helicoverpa armigera Hbn.) (CB) damages in the different breeding season corns. The damage examinations were made in a 29.2 hectares acreage between Igal and Kazsok villages (Somogy county) on the basis of the flight observation at the end of August 2008. We examined the measure of damages and yield losses based on the collected ears belonging to different breeding season corns (FAO 200–299, FAO 300–399, FAO 400–499, FAO 500–599). The relationship between the breeding season and the damages was examined by variance analysis (one-way anova). The collected samples were examined in analytic laboratory in order to calculate the quantitative alteration of the fundamental in-kernel air dry content values (raw protein, raw fat, starch).Our results proved the significant increasing of damage percentages (FAO 200–299: 8.66%; FAO 500–599: 15.33%), surface damages (cm 2 ) (P = 0.026) and the calculated weight loss of damaged ears (P=0.014) parallel with the increasing of the breeding season length. We confirmed the “forced maturing” in the case of the earlier hybrids in the consequence of the damage. We recorded a decreasing percentage (correlate to the draw matter) of the starch and the raw fat (average decreasing: starch: 1.72; raw fat: 0.26) as well as the increasing starch loss per one hectare, agreeing with the breeding season length increase (starch loss/one hectare: FAO 200–299: 1.54%; FAO 500–599: 2.72%). We observed the quantitative increasing of the raw protein as a function of CB’s damage too, which can be explained by a physiological response to the biotic stress