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Title: EFFECTS OF AGE AND SEX ON MORTALITY OF TRIBOLIUM CASTANEUM (COLEOPTERA, TENEBRIONIDAE) EXPOSED TO INSECTO-TREATED WHEAT

Author
item DE PAULA, M - NONE
item Flinn, Paul
item SUBRAMANYAM, BH - KANSAS STATE UNIVERSITY
item LAZZARI, S - FED UNIV OF PARANA

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2002
Publication Date: 10/22/2002
Citation: DE PAULA,M.C., FLINN,P.W., SUBRAMANYAM,B., LAZZARI,S.M., EFFECTS OF AGE AND SEX ON MORTALITY OF TRIBOLIUM CASTANEUM (COLEOPTERA, TENEBRIONIDAE) EXPOSED TO INSECTO-TREATED WHEAT, JOURNAL OF STORED PRODUCTS RESEARCH 75(3):158-162. 2002.

Interpretive Summary: The red flour beetle is one of the most common insect pests of stored grain and is also very common in flour mills and food warehouses. Diatomaceous earth can be used to control stored grain insect pests like the red flour beetle. Insecto is a commercial formulation of diatomaceous earth. Diatomaceous earth abrades and absorbs the water-resistant lipid layer of the insect exoskeleton, causing death by desiccation. We exposed different ages of male and female red flour beetle to Insecto-treated wheat. We found that there was no difference in mortality between male and female beetles. We also found that the age of the insect affected how easily they were killed by Insecto-treated wheat. Adult beetles that were half a day to 2.5-days-old were about 3 to 6 times more likely to be killed by Insecto-treated wheat than were adults that were between 4.5 to 32.5-days-old. Adults that were 64.5-days-old were also more susceptible to Insecto-treated wheat. Therefore, when evaluating the effectiveness of diatomaceous earth, red flour beetle adults between 4.5 and 32.5 days should be used in bioassays to decrease the variability of the results.

Technical Abstract: Insecto is a commercial diatomaceous earth dust registered in the US for grain treatment at 0.5 to 1 g/kg rates. In the laboratory, male and female adults of different specific ages of the red flour beetle, Tribolium castaneum (Herbst), were exposed for 7 days to hard red winter wheat treated with 0.25 g/kg of Insecto at 30 degrees C. and 65% RH. The mortality of T. castaneum adults was similar between the sexes, but varied with adult age. Adults that are 0.5 and 2.5-d-old, and those that were 64.5-d old, were about 3 to 6 times more susceptible to Insecto than 4.5 to 32.5-d old adults. Mortality of 4.5 to 32.5-d-old adults was similar (4.5 to 5.5%) Therefore, when evaluating the efficacy of diatomaceous earth dusts on T. castaneum, unsexed adults between 4.5 and 32.5 days should be used in bioassays to reduce variation in mortality data attributable to adult age.