Environmental Entomology (1997) 26, 265-271

J. Oscar Stapel, John R. Ruberson, Harry R. Gross Jr. and W. Joe Lewis (1997)
Progeny allocation by the parasitoid Lespesia archippivora (Diptera: Tachinidae) in larvae of Spodoptera exigua (Lepidoptera: Noctuidae)
Environmental Entomology 26 (2), 265-271
Abstract: Field-collected Spodoptera exigua (Hübner) larvae always produce small brood sizes of the gregarious parasitoid Lespesia archippivora (Riley) (1-2 progeny). To further investigate this finding we characterized life history attributes of the parasitoid's offspring in different host instars in the laboratory. Changes in offspring fitness and mortality and rate of successful parasitization can indicate opportunities for tachinids to influence fitness of their progeny. Effects of host instar and parasitoid brood size on parasitoid survival, development, size, and fecundity were investigate. Fecundity was indirectly assessed by measuring parasitoid puparial weight; female puparial weight and egg load are positively correlated. L. archippivora is able to successfully parasitize all investigated instars of S. exigua. The percentage of hosts yielding puparia was highest (95.1%) in 4th instars; it was only 65.5% in prepupal stages of the host. Lower parasitoid emergence rates in younger host instars were caused by higher host survival or premature host mortality. Parasitoid puparial weight decreased with increasing brood size but was not affected by host instar when equal brood sizes were compared. Parasitoid puparial weight from broods of 2 offspring was significantly reduced in broods of 2 female progeny compared with that of females from mixed sex broods of 2 progeny. Progeny allocation of L. archippivora and fitness consequences associated with that allocation are independent of host size. We conclude that by consistently allotting small broods to hosts, L. archippivora adults may reduce strong competition between offspring and maximize successful parasitization, thereby resulting in highly fit females.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): John Ruberson

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera exigua
Lespesia archippivora (parasitoid)	Spodoptera exigua