A high incidence of parasitism ofHeliothis SPP. [Lep.: Noctuidae] larvae in cotton in Southeastern Arkansas

Abstract

During 1981 and 1982, bollworm, Heliothis zea (Boddie), and tobacco budworm, H. virescens (F.), larvae (n = 3,666) were collected from 41 cotton fields near Portland, Arkansas (USA) to assess the occurrence of parasitism. Three strategies were employed to control Heliothis spp. in these fields : (1) release of Trichograrnma pretiosum Riley ; (2) insecticidal control ; or (3) inaction (check). Insecticide use in nonchemicat control fields was reduced, but not eliminated. Hetiothis spp. larvae collected in cotton had higher parasitism rates in 1981 (30.9 %) and 1982 (50.1%) than had been reported for cotton since the advent of organochlorine insecticide usage. Four species of larval parasites and 1 species of larval-pupal parasite were recorded. The larval parasite Microplitis croceipes (Cresson) comprised 90.6 % and 94.5 % of all parasitic insects reared from field collected Heliothis spp. in 1981 and l 982, respectively, No difference (P> 0.05) in level of parasitism existed between H. zea and H. virescens. Differences between treatments occurred only in 1982 when H. zea larvae were parasitized at a greater (P<0.05) rate in check fields (68.3 %) than in insecticidal control fields (44.3 % ). Higher levels of larval parasitism in cotton fields may be a consequence of reduced insecticide usage and changes in materials applied, particularly the pyrethroids.

Comparative GC-EAD Responses of A Specialist (Microplitis croceipes) and A Generalist (Cotesia marginiventris) Parasitoid to Cotton Volatiles Induced by Two Caterpillar Species

“…Microplitis croceipes was reared on caterpillars of H. virescens, its preferred host (Stadelbacher et al 1984;King et al 1985), whereas C. marginiventris was reared on caterpillars of its main host S. exigua (Jalali et al 1987). The rearing procedures were similar to those of Lewis and Burton (1970), and the rearing conditions were the same as described above for the caterpillar hosts.…”

Reproductive strategies of the larval parasitoid Microplitis croceipes

“…Mating usually takes place immediately after emergence. Microplitis croceipes reproduce via arrhenotokous parthenogenesis, where unmated females produce only male offspring, whereas mated females produce both female and male off-spring at a ratio of 1:1 to 1.6:1, depending on the host (Lewis & Snow, 1971;King et al, 1985).…”

Estimation of Groundwater Recharge in Limestone Aquifer using an Improved Soil Moisture Balance Method: A Case Study in Jaffna District

“…Among the various groups of biocontrol agents, braconids are well known parasitoids for the management of different lepidopteran larvae, including okra fruit borer complex. King et al, (1985) reported that field release of the braconid parasitoid, Chelonus blackburni Cameron at 50,000 adults ha -1 gave promising control of E. vittella with least fruit infestation of 11.64%. Mani et al, (2005) reported the natural incidence of B. hebetor, B. greeni and Trichogramma spp., on Earias spp.…”