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Impact of braconid wasps on larval performance of longhorned borer Coptocercus rubripes Boisduval (Coleoptera: Cerambycidae) in Eucalyptus forest of southwestern Australia
Author(s) -
Seaton Stephen A,
Hardy Giles E St J
Publication year - 2020
Publication title -
austral entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.502
H-Index - 39
eISSN - 2052-1758
pISSN - 2052-174X
DOI - 10.1111/aen.12502
Subject(s) - longhorn beetle , biology , parasitism , parasitoid , infestation , larva , biological pest control , eucalyptus , ecology , host (biology) , botany
In southwestern Australia, outbreaks of cerambycids have been associated with infestation of drying and stressed trees. Felled timber provides an abundant habitat for a variety of subcortical beetles where their development can be modified by attack from natural enemies, including parasitoids. There are a variety of parasitoid wasps of cerambycids native to Australia, yet their effectiveness in controlling the larval performance of borers has been little studied. Approximately 700 Eucalyptus trees felled to realign a forest road provided an opportunity to determine how a mass of drying logs influences borer infestation rates and whether parasitoid wasps were effective in controlling borer survival. The native borer Coptocercus rubripes (Coleoptera: Cerambycidae) caused an extensive infestation of fallen trees at the clearfell site. These infestations were subsequently limited by the direct effect of parasitism from the native braconid wasps Callibracon limbatus and Syngaster lepidus emerging from a single hole in a white cocoon. The effects of parasitism showed inverse density dependency where high borer larval densities increased the chances of borer larval survival. The absence of parasitism in caged logs promoted high borer larval densities and greatly improved adult borer survival, and while this increased the demand for sapwood resources, it promoted early adult borer emergence. Control by native braconid wasps of high infestations of Co. rubripes borers attacking drying and stressed trees limits adult borer emergence and has the potential to partially regulate borer populations.