Development and Mortality of Tribolium castaneum and T. confusum (Coleoptera: Tenebrionidae) on Seed-Borne Fungi1

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Abstract
The responses of Tribolium castaneum (Herbst) and T. confusum Jacquelin du Val to 23 species of seed-borne fungi and to 1 actinomycete species, cultured on potato-sucrose-agar, were tested at 31°±2°C and 70%±3% RH. Adults of both insects fed voraciously on Alternaria and Mucor sphacrosporus, but adult T. castaneum fed well also on Hormodendrum and Nigrospora, and T. confusum on Mucor silvaticus. T. castaneum laid eggs on 16, T. confusum on 10 species of fungi, and on 1 species T. castaneum laid more eggs than T. confusum. Generally, egg laying was maximum on fungi most suitable as adult food. From 8% to 77% of T. castaneum larvae developed on 8 species of fungi, their developmental periods ranging from 21.5 days on Nigrospora to 131 days on Scopulariopsis. From 3% to 60% of T. confusum completed larval development on 7 species of fungi, with larval periods ranging from 22 days on Nigrospora to 66 days on Absidia. Larval development was complete and most rapid on wheat flour-yeast (95:5) medium, and incomplete on potato-sucrose-agar medium, when these were used as controls. The pupal periods of both insect species ranged between 4 and 7 days, and were not affected by the fungal diets of the larvae. The minimum total developmental period, from egg laying to adult emergence, was 30 days for T. castaneum, 41 days for T. confusum, when larvae of both species fed on Nigrospora. Death of T. castancum larvae occurred between 3 and 12 days when fed on Streptomyces or on fungi of 15 species; larval mortality occurred within 7 days on Trichodenna and Penicillium funiculosum. T. confusum larvae died between 5 and 56 days when fed on Strcptomyces or fungi of 15 species, larval mortality occurring within 6 clays on Aspergillus fumigatus, Penicillium terrestre, and Streptomyces.