Technique to Screen Peanuts for Resistance to the Tobacco Armyworm, Spodoptera litura (Lepidoptera: Noctuidae) Under No-Choice Cage Conditions

Abstract

Peanut is an important oilseed crop in the semi-arid tropics. It is damaged by several insect species, of which tobacco armyworm, Spodoptera litura F., is one of the most damaging pests in South and Southeast Asia. Because of uncertainty of S. litura infestations under field conditions,we standardized a no-choice cage technique to screen germplasm and breeding material for resistance to this insect. The test plants were infested with different densities of first-and third-ins tar larvae at 15 dafter seedling emergence. Maximum differences in leafdamage rating and percentage lossin plant biomass at 7 dafter infestation between JL 24and ICGV 86031were observed when the plants were infested with 10 first-instar larvae perplant. When the plants were infestedwith third-instar larvae,damage evaluationat 48 hr after infestation showed the maximumdifferencesbetweenJL24 and ICGV 86031.Peanut Science (2002) 29:35-40 plant) and ICGV 86031 than on JL 24. Leaf damage rating was Significantly and positively correlated with larval weight and loss in plant biomass. Fifteen-d-old peanut seedlings infested with 10 first-or third-instar larvae can be used to evaluate peanut germplasm and segregating breeding material for resistance to leafdefoliators such as S. litura.

Mechanisms and Diversity of Resistance to Insect Pests in Wild Relatives of Groundnut

“…Screening for Resistance to S. litura Under No-Choice Conditions in the Greenhouse. To conÞrm the reaction of different accessions observed under Þeld conditions, 28 accessions of wild relatives, and three checks of the cultivated groundnut were screened for resistance to S. litura under no-choice conditions in the greenhouse (Sharma et al 2002). Twelve derivatives of wild relatives and eight cultivated genotypes were also evaluated for resistance to S. litura.…”

“…Plants were infested at 15 d after seedling emergence. One plant in each pot was covered with a plastic jar cage (11 cm diameter, 26 cm in height) with two wire-mesh screened windows (4 cm diameter) on the sides (Sharma et al 2002). The top of the plastic jar cage was covered with a lid Þtted with wire-mesh screen.…”

Mechanisms and Diversity of Resistance to Insect Pests in Wild Relatives of Groundnut

“…To conÞrm the reaction of different accessions observed under Þeld conditions, 28 accessions of wild relatives, and three checks of the cultivated groundnut were screened for resistance to S. litura under no-choice conditions in the greenhouse (Sharma et al 2002). Twelve derivatives of wild relatives and eight cultivated genotypes were also evaluated for resistance to S. litura.…”

“…One plant in each pot was covered with a plastic jar cage (11 cm diameter, 26 cm in height) with two wire-mesh screened windows (4 cm diameter) on the sides (Sharma et al 2002). The top of the plastic jar cage was covered with a lid Þtted with wire-mesh screen.…”