Elevated temperatures (50-60oC) are often used to disinfest insect pests in food-processing facilities as an alternative to methyl bromide fumigation. We found that first instars (young larvae) of the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), were relatively more tolerant than eggs, old larvae, pupae, and adults to elevated temperatures. To determine whether heat shock proteins (HSP) mediate the increased thermotolerance in T. castaneum life stages, we examined HSPs by western blot analysis using monoclonal anti-HSP70 from mouse in eggs, young larvae, old larvae, pupae and adults of T. castaneum reared at 23oC and exposed at 28o or 40oC for 1 h. Our results revealed constitutive expressions of HSP70 in all stages of the insect. However, the expression of HSP70 in young larvae increased by about 1.5 fold after the larvae was exposed at 40oC for 1 h. For the other stages, the expression of HSP70 did not vary significantly. Molecular masses of HSP70 among different stages ranged from 68.4 °À 1.3 to 86.8 °À 3.9 kDa. However, young larvae possessed two distinct HSPs with molecular masses of 72.8 °À 1.7 and 17.2 °À 0.7 kDa both recognized by the HSP70 antibody. Our study suggests that increased thermotolernace in young larvae could be due to either increased expression of HSP70 at higher temperatures and/or the additional HSP with lower molecular mass. Further work will focus on molecular characterizations of different HSPs in relation to different exposure temperature and time in young larvae
Species 1: Coleoptera Tenebrionidae Tribolium castaneum (red flour beetle)
Keywords: heat shock proteins
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