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Title: Biology of two members of the Euwallacea fornicatus species complex (Coleoptera: Curculionidae: Scolytinae), recently invasive in the U.S.A., reared on an ambrosia beetle artificial diet

item Cooperband, Miriam
item STOUTHAMER, RICHARD - University Of California
item CARILLO, DANIEL - University Of Florida
item ESKALEN, AKIF - University Of California
item THIBAULT, TIMOTHY - Huntington Library, Art Collections, And Botanical Gardens
item Cosse, Allard
item CASTRILLO, LOUELA - Cornell University
item Vandenberg, John
item RUGMAN-JONES, PAUL - University Of California

Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2016
Publication Date: 6/23/2016
Citation: Cooperband, M.F., Stouthamer, R., Carillo, D., Eskalen, A., Thibault, T., Cosse, A.A., Castrillo, L.A., Vandenberg, J.D., Rugman-Jones, P.F. 2016. Biology of two members of the Euwallacea fornicatus species complex (Coleoptera: Curculionidae: Scolytinae), recently invasive in the U.S.A., reared on an ambrosia beetle artificial diet. Agricultural and Forest Entomology. 18:223-237. doi: 10.1111/afe.12155.

Interpretive Summary: Three morphologically indistinguishable species of exotic ambrosia beetles (Euwallacea fornicatus ) that are vectors of a fungal pathogen are causing significant damage to commercial grown avocados in California, Florida, and Israel. Timely research to improve our understanding of the biology of these species, develop tools for trapping and detection, and investigate mitigation options such as biological control is required. Such research would be greatly expedited by the ability to rear the beetles in the laboratory. This study describe successful laboratory rearing techniques for two members of the E. fornicatus species complex, and report the findings of studies conducted to characterize basic biological attributes of both species.

Technical Abstract: 1. Diet and rearing protocols were developed for two members of the cryptic Euwallacea fornicatus species complex, polyphagous shot hole borer (PSHB) and tea shot hole borer (TSHB) (Coleoptera: Curculionidae: Scolytinae), using sawdust from boxelder Acer negundo and avocado Persea americana. 2. Biology, phenology, and sex ratio data were recorded. Adults developed in as few as 22 d at 24 deg C. A single PSHB or TSHB foundress produced on average 32.4 and 24.7 adult female offspring, respectively, and a maximum of 57 and 68 female adults in 6-7 weeks. 3. The number of entry holes was a strong predictor of the number of offspring in a colony. 4. Virgin foundresses first produced male offspring, mated with a son, then produced female offspring. 5. Average sex ratios (% male) for offspring of mated PSHB and TSHB, respectively, were 7.4% and 7.2%, and were not significantly affected by colony age. PSHB sex ratios also were not affected by foundress number as predicted by Hamilton’s local mate competition (LMC) theory. 6. Males did not usually eclose before females as predicted by LMC theory, but they eclosed around the same time (22-23 d). That, and the fact that offspring sex ratio did not change with foundress number, are contrary to expectations of LMC theory. 7. A cold tolerance study found highest mortality rates among PSHB colonies exposed to below freezing temperatures (-5 deg or -1 deg C), but colonies exposed to near-freezing temperatures (0 deg, 1 deg, or 5 deg C) did not produce significant mortality.