Applied Entomology and Zoology (1997) 32, 283-291

Satoshi Nakamura (1997)
Clutch size regulation and host discrimination of the parasitoid fly, Exorista japonica (Diptera: Tachinidae)
Applied Entomology and Zoology 32 (2), 283-291
Abstract: The ability of Exorista japonica females to regulate clutch size in response to host density was investigated in the laboratory. On the assumption that the flies can estimate host density by the frequency of host encounters, the effect of time interval between host encounters and the number of hosts offered on the oviposition decision of female flies was studied, and host discriminatory ability was examined. A female fly was offered a cup (considered as a patch) containing host(s) at various time intervals. Clutch size decreased as the time interval between host encounters was shortened and as host density per patch increased. The number of eggs laid per patch during a single attack increased with increases in the time interval between host encounters was lengthened and as host density per patch increased, even at a constant time interval. Females discriminated between unparasitized and parasitized hosts when the parasitized host contained 10 eggs, but did not discriminate when the parasitized host had only 5 eggs. Moreover, the time interval between host encounters affected host discrimination. Females oviposited equally on an unparasitized and a parasitized host with 10 eggs when they encountered hosts at 24 h intervals, but they laid fewer eggs on the parasitized host when the interval between host provisions was 1 min. The results indicated that E. japonica females not only regulated clutch size in relation to host availability but also discriminated between unparasitized and parasitized hosts.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Satoshi Nakamura

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.
Exorista japonica (parasitoid)			Japan