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United States Department of Agriculture

Agricultural Research Service

Research Project: IPM-BASED STRATEGIES FOR INCORPORATING MICROBIAL BIOLOGICAL CONTROL FOR MANAGEMENT OF GREENHOUSE AND NURSERY CROP PESTS

Location: Biological Integrated Pest Management Unit

Title: Brood production by Xylosandrus germanus (Coleoptera: Curculionidae) and growth of its fungal symbiont on artificial diet based on sawdust of different species

Authors
item Castrillo,, L. -
item Griggs, Michael
item Vandenberg, John

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 29, 2012
Publication Date: August 1, 2012
Citation: Castrillo,, L.A., Griggs, M., Vandenberg, J.D. 2012. Brood production by Xylosandrus germanus (Coleoptera: Curculionidae) and growth of its fungal symbiont on artificial diet based on sawdust of different species. Environmental Entomology. 41:822-827.

Interpretive Summary: The ambrosia beetle Xylosandrus germanus is among the most important exotic pests of orchards and nurseries in the U.S. It attacks a wide range of woody plant hosts and is difficult to control using conventional insecticides. As part of our studies on the biology and control of this beetle, we are trying to optimize conditions for rearing beetles in the laboratory. For this study we tested the reproductive output of individual females reared on an artificial sawdust-based diet. We used sawdust from four tree species, American beech, black walnut, European buckthorn and red oak. We also tested the growth of different strains of the beetle’s symbiotic fungus, Ambrosiella hartigii, on these sawdust diets. We found a significantly higher average number of progeny produced on diet made with sawdust from European buckthorn (44) compared to those made with American beech (29), black walnut (26), or red oak (26). The percentage of females producing brood and the ratio of females:males were not affected by the type of sawdust. Sex ratio, however, was significantly affected by progeny size. In smaller broods the ratio observed was approximately 10:1 females:males, but in larger broods the ratio approached 20:1. Growth of the fungal symbiont varied with strain and with sawdust. A strain representing a common genotype from beetles from OH populations showed faster growth on European buckthorn infusion medium. Optimized rearing conditions will make further laboratory studies feasible. Our findings indicate that plant hosts can influence success of beetles, and their symbiont, in the field.

Technical Abstract: The ambrosia beetle Xylosandrus germanus (Blanford) (Coleoptera: Curculionidae) is among the most important exotic pests of orchards and nurseries in the US. It attacks a wide range of hosts and is difficult to control using conventional insecticides. As part of our studies on the biology and control of X. germanus, we are trying to optimize conditions for mass rearing in the laboratory. In this study we tested the brood production of X. germanus from OH reared on artificial diet based on sawdust from American beech, black walnut, European buckthorn and red oak. We also tested the growth of different strains of its fungal symbiont, Ambrosiella hartigii Batra (Ascomycota: Ophiostomales), on these sawdust diets. Among the sawdust species tested, we found a significantly higher average number of progeny produced on diets made with sawdust from European buckthorn (43.9 plus or minus 1.7) compared to those made with American beech (28.9 plus or minus 1.8), black walnut (25.5 plus or minus 1.9), or red oak (26.3 plus or minus 1.8). The percentage of females producing brood and the ratio of females to males were not affected by sawdust. Sex ratio, however, was significantly affected by progeny size, with fewer males produced as the number of progeny increased. In smaller broods the ratio observed was approximately to 10 to 1; in larger broods it approached 20 to 1. Growth of the fungal symbiont varied with strain and with sawdust. Strain XgOH11, representing a common genotype from X. germanus from OH populations showed faster growth on buckthorn infusion medium, suggesting resource-dependent brood production by foundresses.

Last Modified: 9/1/2014
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