Austral Entomology (2014) 53, 104-111

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Paul W. Walker and Geoff R. Allen (2014)
Sex-biased parasitism of adult spring beetles, Heteronyx dimidiata and Heteronxy crinitus, by Tachinidae in Eucalyptus nitens plantations in Australia
Austral Entomology 53 (1), 104-111
Abstract: Parasitism of adult Heteronyx dimidiata (Erichson) and H. crinitus Blackburn (Scarabaeidae: Melolonthinae), that attack Eucalyptus nitens plantation seedlings in southern Australia, was recorded over 3 years. An undescribed genus of Blondeliini (Tachinidae: Exoristinae) was reared from both scarab species while a Palpostoma sp. (Tachiinae) was reared from H. crinitus. Flies were observed parasitising flying beetles by intercepting them mid-air. Eggs were laid externally on the exoskeleton, mainly on the dorsum of abdominal tergites. Male H. dimidiata were parasitised significantly more (40%) than female conspecifics (13%) and male or female H. crinitus (both 13%), which was attributed to their greater flight activity searching for mates. Superparasitism was common in both species, particularly in male H. dimidiata (56% of parasitised beetles, up to 22 eggs/beetle), despite evidence that only a single tachinid could complete development in a beetle. Early stages of parasitism in H. dimidiata females did not appear to affect ovarian development nor the ability of beetles to feed on young trees. However, we infer that the tachinids had a significant impact on Heteronyx spp. populations through a reduction in adult beetle longevity and fitness.
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Link to article at publishers website
Database assignments for author(s): Paul W. Walker

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

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Heteronyx dimidiata Eucalypt (Eucalyptus) Australia (South+SE)
Heteronyx crinitus Eucalypt (Eucalyptus) Australia (South+SE)
Palpostoma (genus - parasitoids) Heteronyx crinitus Eucalypt (Eucalyptus) Australia (South+SE)