Meteorus gyrator (Thunberg) (Hymenoptera: Braconidae) In Egypt: Geographical Distribution and Mass-production

Background: The larval internal parasitoids in the genus Meteorus attack certain lepidopterous larvae in different Egyptian fields. Two species, M. rubens and M. gyrator were the most abundant species reared from several lepidopterous larval species, which feed on different host plants in the two selected Governorates in Egypt throughout two successive years. Aim: This work presents a method specifically designed to improve the abundance and the parasitizing potential of M. gyrator in open fields to parasitize and develop on a broad range of noctuid’s pests by releasing considerable number of the parasitoid adults. Also it deals with some aspects of the basic biology of M. gyrator parasitizing Spodoptera littoralis and Autugrapha ni, as mass-rearing hosts. Methodology: 1- Population Dynamics Biweekly samples of lepidopterous larvae were collected from different host plants in the fields of Giza and Faiyum Governorates, for two successive years (November, 2017 to October, 2019). Collected larvae were confined individually under constant conditions until pupation or the emergence of the internal parasitoid’s larvae for pupation. 2- Laboratory Rearing Cultures of some insect larvae, Heliothis armigera, Spodoptera exigua, Agrotis ipsilon, Sesamia cretica, S. littoralis and Autographa ni were reared in laboratory under constant conditions to act as hosts for mass-production of the parasitoid, M. gyrator. Results: Obtained results reveal that A. ipsilon was the main host of M. rubens, it was more abundant in both years and localities of the survey. Meteorus gyrator was recorded at fewer numbers; it was reared from S. littoralis, S. exigua, S. critica, Heliothis spp. and Autographa spp. The parasitism percentage by M. rubens averaged 23.10% at Giza. While in the case of M. gyrator it averaged 3.25%. In Faiyum, the corresponding figure averaged 12.96% parasitism for M. rubens; while it averaged 6.93%, for M. gyrator. To increase the efficacy of M. gyrator, mass production experiments were carried out, suggesting that Autographa ni was the most suitable for mass-rearing than S. littoralis. Conclusion: To increase the efficacy of M. gyrator as an endoparasitoid, its numbers in the field should be increased by releasing a considerable number of adults, to control lepidopterous larval pests.

Evaluación de trampas con atrayentes alimenticios para gusano soldado en garbanzo

El cultivo de garbanzo es afectado por un complejo de lepidópteros, dominando Heliothis spp. y Spodoptera spp., los cuales afectan entre 10-80% de su productividad. El combate de estas plagas, se hace mediante un muestreo visual de huevecillos y posterior aplicación de insecticidas; sin embargo, dicho muestreo da información incorrecta de densidad y especies presentes. Actualmente el uso de trampas cebadas con atrayentes alimenticios y feromonas sexuales, complementa la información generada por los muestreos visuales y proporciona datos más exactos para el monitoreo de la plaga. El objetivo del estudio fue evaluar atrayentes alimenticios y sexuales, y su capacidad de atracción a palomillas de Spodoptera exigua en el cultivo de garbanzo. En el estudio se utilizó un diseño experimental completamente al azar, con tres repeticiones. Los tratamientos fueron atrayente alimenticio comercial (Noctovi©), levadura + azúcar, levadura, polen de quelite y feromona sexual específica de S. exigua; y un testigo sin feromona sexual o atrayente. Las variables evaluadas, fueron poblaciones de palomillas de S. exigua, durante todo el periodo que comprendió el estudio. Los tratamientos donde se identificó mayor atracción y captura de palomilla adulta en las trampas cebadas fueron los tratamientos a base de levadura más azúcar y el comercial Noctovi©, siendo este último el que obtuvo mejores resultados como atrayente en las trampas cebadas para el gusano soldado (S.exigua), lo que lo convierte en potencial herramienta a ser considerada parte de un programa integral de muestreo de esta plaga.

Contamination of Arthropod Predators with Heliothis Nuclear Polyhedrosis Virus After Elcar™ Applications to Soybean for Control of Heliothis spp. (Lepidoptera: Noctuidae)2,3

Application of Elcar™ [Heliothis nuclear polyhedrosis virus (NPV)] to soybean at 9 × 1010 and 36 × 1010 polyhedral inclusion bodies (PIB) per ha resulted in only low levels of mortality (7% to 26.0%) from NPV in Heliothis spp. larvae collected up to 14 days after treatment. Bioassay of NPV in predators collected from 36 × 1010 PIB/ha-treated plots revealed that 16.9% and 14.8% were contaminated with virus 7 and 14 days, respectively, after application. The predominant predators collected were spiders (34.3%) and nabid species (29.2%) of which 11.0% and 20.2%, respectively, tested positive for NPV. Only a few predators collected from outside treated plots 14 days after treatment contained NPV. These results suggest that most predators which preyed on virus infected larvae did not move from the treated plots and did not have an important role in NPV dispersal within the treated plots.

Multicellular Rearing Methods for the Beet Armyworm, Soybean Looper, and Velvetbean Caterpillar (Lepidoptera: Noctuidae)

Methods used for rearing Heliothis spp. larvae in a multicellular container were modified for rearing beet armyworm (BAW), Spodoptera exigua (Hübner), soybean looper (SBL), Pseudoplusia includens (Walker), and velvetbean caterpillar (VBC), Anticarsia gemmatalis (Hübner). Polyester-cotton cloth used for Heliothis oviposition was unsatisfactory for BAW, SBL, and VBC. A polyester-cotton cloth with a dimpled surface was discovered which was suitable for all three species. Beet armyworm eggs were removed from the oviposition cloth and disinfected with sodium hypochlorite. This procedure could not be used for SBL or VBC as it resulted in significant reduction in egg hatch. New methods were developed for placing BAW, SBL, and VBC eggs into a multicellular container. A separator and high volume blower used to harvest Heliothis pupae was also used to harvest BAW and VBC pupae. SBL pupae, because of webbing spun by the larvae prior to pupation, could not be harvested in this manner. A pupal harvest method was developed for SBL. A phosphoric-propionic acid mix incorporated into the larval diet controlled contaminants. These procedures have been used since 1986 at Stoneville and more than ¾ million pupae and 100 million eggs were reared in 1987 and 1988.

MORTALITY OF FALL ARMYWORM, SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE) EGGS, LARVAE AND ADULTS EXPOSED TO SEVERAL INSECTICIDES ON COTTON

Mortality of eggs, first, third, and fifth instars and adults of fall army worm (FAW), Spodoptera frugiperda (J. E. Smith), after exposure to several insecticides on cotton indicated that the FAW is susceptible to most insecticides currently used to control Heliothis spp. Most insecticides tested exhibited ovicidal activity. High mortality of first instar larvae was observed for most treatments, including the biological insecticide, Bacillus thuringiensis (Berliner). More variation in mortality among treatments was observed in third and fifth instars than in first instars. Pyrethroid, carbamate, and organophosphorous insecticides resulted in higher mortality than did B. thuringiensis. Diflubenzuron, an insect growth regulator, was as effective as commonly used insecticides against third and fifth instar larvae when mortality was observed at pupation. Third instar FAW placed on plant tissue from the upper section of cotton plants sprayed in field situations suffered higher mortality than those placed on plant tissue from lower sections in the plant canopy. Inadequate deposition of insecticide in the lower portions of the cotton plant appears to be a limiting factor in control of FAW larvae on cotton.