Temperature mediates life history, energy reserves, and host selection of Trogoderma granarium Everts (Coleoptera: Dermestidae)

Abstract

We examined how diet and temperature affect developmental time and survival of immature stages, adults’ longevity, fecundity, and energy reserves of Trogoderma granarium Everts (Coleoptera: Dermestidae), a cosmopolitan pest of grains and other stored products. Also, we studied whether and to what extent the temperature impacts the host selection by larvae. Beetles were reared under five temperature regimes (21, 25, 29, 33, and 37 °C, 65 ± 5% R.H. and a photoperiod of 14L: 10D h) and fed with three commodities (barley, walnut, and wheat). At 29, 33, and 37 °C, the shorter immature developmental time and higher survival rate of T. granarium were on wheat, followed by barley and walnut. A diapause-like state was induced in the last instar larvae fed barley at 25 and 21 °C and wheat at 21 °C. In contrast, the beetles fed walnut completed their life cycle and successfully oviposited at these temperatures. At 21 and 25 °C, walnut attracted a higher density of larvae in a free-choice condition. Conversely, wheat attracted more larvae at 29, 33, and 37 °C, and the lowest number of larvae was observed on walnut. The walnut-fed larvae had a higher content of lipids than wheat- and barley-fed larvae. The present study highlights the need to account for temperature effects when studying the food preferences of insects and to consider further characteristics that may impact host selection. Our findings allow us to anticipate the population dynamics of T. granarium on different commodities according to environmental temperature.