Environmental Entomology (1983) 12, 1356-1359

S.J. Johnson (1983)
Effect of larval crowding on pupal parasitism in Alabama argillacea (Lepidoptera: Noctuidae)
Environmental Entomology 12 (5), 1356-1359
Abstract: A cause and effect relationship was demonstrated between cotton leafworm, Alabama argillacea (Hübner), larval crowding, and increased parasitism by the pupal parasite Brachymeria ovata (Say). In overcrowded conditions the larvae exhibited a conspecific-destructive reaction by resorting to eating the leaf covering from the pupae of their own species, thus destroying needed protection from natural enemies. The minimum larval density required before larvae consumed pupal leaf covers and exposed the pupae was 18.4/m of row, with a larval density of 142.1/m of row resulting in almost complete defoliation and consumption of most pupal covers. Parasitism of covered pupae by B. ovata was 1.0 ± 0.6 to 4.9 ± 1.7%, whereas 30.3 ± 9.7 to 46.6 ± 6.2% of the exposed pupae produced under crowded conditions were parasitized. Intraspecific competition between the cotton leafworm larvae and pupae is unequal because the larvae have a marked effect on pupal survival, but there is no detectable, reciprocal effect on the larvae. In most cases of intraspecific competition, the relatively successful individuals are those that begin and complete development first. However, in the case of the cotton leafworm, the opposite may be true.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Seth J. Johnson

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
environment - cropping system/rotation
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Alabama argillacea	Cotton (Gossypium)	U.S.A. (mid S)
Brachymeria ovata (parasitoid)	Alabama argillacea