Does cannibalism in Spodoptera frugiperda (Lepidoptera: Noctuidae) reduce the risk of predation? |
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Authors: | J W Chapman Trevor Williams Ana M Martínez Juan Cisneros Primitivo Caballero Ronald D Cave Dave Goulson |
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Institution: | (1) Biodiversity and Ecology Division, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, SO16 7PX, UK, GB;(2) ECOSUR, Tapachula 30700, Chiapas, Mexico, MX;(3) Departamento de Producción Agraria, Universidad Pública de Navarra, 31006 Pamplona, Spain, ES;(4) Departamento de Protección Vegetal, Escuela Agrícola Panamericana, Apartado Postal 93, El Zamorano, Honduras, HN |
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Abstract: | The incidence of cannibalism of larval Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize under field conditions was investigated using field cages. Cannibalism was found to account
for approximately 40% mortality when maize plants were infested with two or four fourth-instar larvae over a 3-day period.
Field trials examined the effect of larval density on the prevalence of natural enemies of S. frugiperda. The abundance of predators (earwigs, staphylinids, other predatory beetles, and Chrysoperla spp.) was significantly greater on maize plants with higher levels of larval feeding damage, while the relationship between
predator abundance and number of S. frugiperda larvae per plant was less clear. As larval damage is probably a more reliable indicator of previous larval density than numbers
collected at an evaluation, this indicates that predation risk will be greater for larvae living in large groups. Parasitism
accounted for 7.1% mortality of larvae in sorghum, and involved six species of Hymenoptera and Tachinidae. There was no effect
of larval density or within-plant distribution on the probability of larval attack by parasitoids. The selective benefits
of cannibalism, in relation to the risk of predation and parasitism, are discussed.
Received: 23 March 2000 / Accepted: 24 June 2000 |
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Keywords: | Spodoptera frugiperda Cannibalism Predation Parasitism |
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