Ecological Entomology (2020) 45, 493-497

Toshinori Okuyama (2020)
Concurrently burrowing host fly larvae reciprocally enhance pupation depth to minimise parasitism risk
Ecological Entomology 45 (3), 493-497
Abstract: - Variation in parasitism risk among hosts is a key factor influencing host–parasitoid interactions; however, within-patch variation (as opposed to between-patch variation) in parasitism risk has hardly been studied. This study investigated the mechanisms of within-patch variation in parasitism risk in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae).
- Bactrocera dorsalis pupates underground. Previous studies have shown that pupae at greater depths have a reduced risk of parasitism by a pupal parasitoid Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae). When a pupa near the ground surface is parasitised, the victim may decrease the risk of parasitism risk for pupae located at deeper depths. It was hypothesised that larvae will pupate at greater depths when they perceive the presence of conspecifics because of the benefit of pupating deeper than other individuals.
- In a series of laboratory experiments, the effects of three factors on pupation depth were examined, including: (i) the density of larvae during development; (ii) the density of concurrently burrowing larvae; and (iii) the presence of pre-existing pupae in the pupation substrate. Only the density of concurrently burrowing larvae influenced pupation depth, which suggests that when a burrowing larva perceives the presence of other burrowing larvae, it aims to burrow deeper than them.
- This study shows not only that parasitism risk is variable among pupae within a patch, but also that it is density-dependent. A commonly made assumption (i.e. the absence of within-patch variability in parasitism risk) needs to be re-evaluated in a wide range of host–parasitoid systems.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Toshinori Okuyama

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Bactrocera dorsalis
Dirhinus giffardii (parasitoid)	Bactrocera dorsalis