F. E. Gilstrap

Life-fertility tables of Bracon hebetor Say (Hymenoptera: Braconidae) reared on Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae).

Life-fertility tables were described for Bracon hebetor Say (Hymenoptera: Braconidae) developing on the millet head caterpillar (MHC), Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae). Mated B. hebetor females lived an average of 24.7 days, oviposited ca. 22 days, and produced 173.7 adult progeny with a 1:1 sex ratio. The estimated innate capacity of increase (rc) and net reproductive rate (R0) were 0.26 and 86.5, respectively. The mean generation time was 17 days.RésuméLes tables de vie et fécondité ont été décrites pour Bracon hebetor Say (Hymenoptera: Braconidae) se développant sur la mineuse de l’épi du mil, Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae). En moyenne, les femelles fécondées de B. hebetor vécurent 24,7 jours, ont pondu pour une durée de 22 jours, et ont produit une progéniture de 173,7 adultes avec un sexe ratio de 1:1. Le taux d’accroissement (rc) de la population et le taux reproductif net (R0) étaient de 0,26 et 86,5, respectivement. La durée moyenne d’une génération était de 17 jours.

Population dynamics and parasitism of Coniesta(= Haimbachia) ignefusalis, Sesamia calamistis, and Heliocheilus albipunctella in millet monoculture

Studies were conducted in Niger in 1986 and 1987 on the population dynamics and parasitism of the millet stem borer, Coniesta (=Haimbachia) ignefusalis (Hampson) (Lepidoptera:Pyralidae), Sesamiacalamistis Hampson, and the millet head caterpillar, Heliocheilus albipunctella de Joannis (Lepidoptera:Noctuidae). Planting dates were assessed for effects on population densities of C. ignefusalis and H. albipunctella. Population densities of C. ignefusalis were not reduced by adjusting millet planting dates, but were affected by millet growth stage. Platytelenomus sp. (Hymenoptera: Scelionidae) was the most common parasite of C. ignefusalis on millet. Parasitism of C. ignefusalis larvae and pupae was rare. Sesamia calamistis was a minor pest of millet in Niger, and was rarely parasitized. Population densities of H. albipunctella were reduced by delaying millet planting dates. Bracon hebetor (Hymenoptera: Braconidae) was the most common parasite of H. albipunctella.RésuméDes études étaient menées en 1986 et 1987 sur la dynamique et le parasitisme du foreur des tiges du mil, Coniesta (= Haimbachia) ignefusalis (Hampson) (Lepidoptera: Pyralidae), de Sesamia calamistis Hampson, et de la mineuse de l’épi du mil, Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae). L’influence des dates de semis sur les densités des populations du foreur des tiges du mil, et de la mineuse de l’épi de mil a été évaluée. Les densités des populations de C. ignefusalis n’étaient pas réduites par l’effet des changement des dates de semis, mais étaient affectées par le stade de développement du mil. Platytelenomus sp. (Hymenoptera: Scelionidae) était le plus fréquent parmi les parasites de C. ignefusalis sur le mil. Le parasitisme des larves et chrysalides de C. ignefusalis était rare. S. calamistis n’était pas un important nuisible du mil au Niger, et était rarement parasité. Les densités des populations de la mineuse de l’épi du mil étaient réduites en retardant les dates de semis du mil. Bracon hebetor Say (Hymenoptera: Braconidae) était le plus fréquent parasite de la mineuse de l’épi du mil.

Six-Spotted Thrips: A Gift from Nature that Controls Spider Mites

The six-spotted thrips, Scolothrips sexmaculatus, provides natural control of spider mites in some habitats, and may be effective in other habitats not currently known. S. sexmaculatus approximates an ideal predator. Its power of increase, compared with that of Tetranychus urticae Koch (a common prey), is greater at low temperatures, and would be greater if only the critical net power of increase is considered for T. urticae. S. sexmaculatus is not discriminating about the stage of prey, has a wide range of prey species and host plants, is predatory and reproductive within a wide range of temperatures, consumes large numbers of prey, has a high searching capacity, is well synchronized with its prey, requires relatively few prey to survive, is an effective searcher at low prey densities, and produces a relatively high number of eggs for each prey individual killed.

Regulation of citrus blackfly (Homoptera: Aleyrodidae) by Encarsia opulenta (Hymenoptera: Aphelinidae) on Texas citrus

Abstract Research conducted in the lower Rio Grande Valley of Texas clarified the role of Encarsia opulenta Silvestri as an effective natural enemy regulator of citrus blackfly, Aleurocanthus woglumi Ashby. Following the natural colonization and increase of E. opulenta , citrus blackfly infestations on commercial citrus declined appreciably and remained at greatly reduced levels during the subsequent 2-year period (1979–1981). Evidence that this trend was primarily an effect of parasitism was obtained in field experiments that collectively demonstrated a significantly higher average rate of mortality and lower replacement among host clusters detected by parasites relative to contemporaries that escaped detection (by chance or deliberate exclusion). Infestations devoid of parasites on residential citrus increased to damaging levels (235 live forms/leaf), but were suppressed to levels E. opulenta . Studies demonstrated the ability of E. opulenta to effectively suppress high-density host infestations within a relatively brief time span and to maintain a stable interaction with its host at low densities for indefinite periods.

Storage of Phytoseiulus persimilis for aerial release (Acari: Phytoseiidae)

Abstract Studies were conducted on the mobility and survival of Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) after short-term refrigerated storage in a simulated aerial delivery system. Storage of P. persimilis was significantly affected by exposure to temperatures of 1.7 degrees, 7.2 degress, 12.8 degrees and 18.3 degrees C, and when stored for 0.5, 1.0 and 1.5 hr. Loss of predators from the simulated hopper was reduced by decreasing the storage time and temperature. The density of predators in the release systems simulated hopper was greatest in the upper one-third of the hopper.