Susceptibility of Tribolium castaneum (Coleoptera: Tenebrionidae) and Trogoderma inclusum (Coleoptera: Dermestidae) to cold temperatures

• Life stages and species of stored product insects vary in their response to cold temperatures.
• Trogoderma inclusum is more tolerant to cold temperature than Tribolium castaneum.
• Larvae of Trogoderma inclusum were the most tolerant life stage to cold temperature.

Studies were conducted by exposing different life stages of Tribolium castaneum (Herbst), the red flour beetle, and Trogoderma inclusum (LeConte), the larger cabinet beetle, for different time intervals to −18 °C. Assessments were made of direct mortality to eggs, larvae, and adults, and eventual adult emergence of immatures. Data were described by non-linear equations. The eggs and larvae were the most tolerant life stage of T. castaneum. Eight hours of exposure were required for 100% kill of 3–4-day-old eggs and 0–10- and 11–21-day-old larvae, but only 4, 0.5, and 0.5 h respectively were required to completely inhibit adult emergence. For T. inclusum, the most tolerant life stage was 15–28-day-old larvae; 64 and 16 h respectively were required for complete mortality and inhibition of adult emergence. Results indicate that T. inclusum was the more tolerant species, and specific treatment protocols may be required for different stored product beetle species when using −18 °C as a disinfestation strategy.