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United States Department of Agriculture

Agricultural Research Service

Research Project: POSTHARVEST TREATMENT OF TROPICAL COMMODITIES FOR QUARANTINE SECURITY, QUALITY MAINTENANCE, AND VALUE ENHANCEMENT Title: Effect of Irradiation on Longevity and Reproduction of Pheidole megacephala (Hymenoptera: Formicidae) Queens

Authors
item Follett, Peter
item Taniguchi, Glenn - UNIV OF HAWAII

Submitted to: Hawaiian Entomological Society Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 2007
Publication Date: December 31, 2007
Citation: Follett, P.A., G. Taniguchi. 2007. Effect of irradiation on longevity and reproduction of Pheidole megacephala (Hymenoptera: Formicidae) queens. Proc. Hawaiian Entomol. Soc. 39: 43-47.

Interpretive Summary: The presence of hitchhiking ants can interrupt exports of fruit, vegetables, and other horticultural products from Hawaii. Irradiation is a quarantine treatment option to control ants and other hitchhiker pests on fresh commodities exported from Hawaii. The radiotolerance of the bigheaded ant, Pheidole megacephala, was studied to determine a dose sufficient for its control. The desired response with irradiation treatment of ants is sterility of reproductive queens. Queens in micro-colonies were irradiated at 60, 90, 120, or 150 Gy or left untreated as controls, then followed for 19 weeks to observe colony growth. Irradiation treatment significantly reduced the number of eggs laid. In the 60 Gy treatment, the number of eggs observed was reduced by 89.6% compared with the untreated controls. In the 120 Gy and 150 Gy treatments, the number of eggs observed was reduced by 99.5% and 98.5%, respectively, and eggs were observed only on the first sampling date. No larvae or pupae were observed in the 90, 120, or 150 Gy treatments, suggesting these irradiation doses were sufficient to sterilize queens.

Technical Abstract: Irradiation is a quarantine treatment option to control ants and other hitchhiker pests on fresh horticultural products exported from Hawaii. The radiotolerance of the bigheaded ant, Pheidole megacephala, was studied to determine a dose sufficient for its control. This ant was chosen as a representative species because it is relatively easy to rear in the laboratory. The desired response with irradiation treatment of ants is sterility of reproductive queens. Queens in micro-colonies were irradiated at 60, 90, 120, or 150 Gy or left untreated as controls, then followed for 19 weeks to observe colony growth. Irradiation treatment significantly reduced the number of eggs laid. In the 60 Gy treatment, the number of eggs observed was reduced by 89.6% compared with the untreated controls. In the 120 Gy and 150 Gy treatments, the number of eggs observed was reduced by 99.5% and 98.5%, respectively, and eggs were observed only on the first sampling date. No larvae or pupae were observed in the 90, 120, or 150 Gy treatments, suggesting these irradiation doses were sufficient to sterilize queens.

Last Modified: 11/27/2014
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