Development, relative retention, and fecundity of Tribolium castaneum (Herbst) on different starches

Abstract

The development, relative retention, and fecundity of the red flour beetle, Tribolium castaneum (Herbst), on six different types of starches, flour, and flour plus yeast were investigated in the laboratory. The size of 90% of particles among the starches was below 15 to 58 μm, while that of the flour was below 133 μm. Larval length, head capsule width, and weight gain of T. castaneum were measured by rearing larvae on starches, flour, and flour plus 5% (by wt) Brewer’s yeast diet for 30 d at 28oC and 65% r.h. Larvae reared on flour or flour plus yeast developed normally and showed better survival compared to those reared on starches. Larvae on starches failed to develop beyond second and rarely third instars. Adults of T. castaneum did not show any preference to flour over starches in dual-choice tests. Tribolium castaneum laid less than 3 eggs/female over a 15 d period on all starches, but laid 97 and 109 eggs/female on flour and flour plus yeast diet, respectively. These initial studies suggest that starches are poor substrates for development, and currently experiments are in progress to improve larval survival and development by incorporating specific nutrients in starches. Starches were as attractive as flour to adults; however, starches do not appear to be a suitable medium for egg-laying. Preliminary experiments by moving adults between starches and flour and vice versa showed that feeding on suitable diets is essential for eliciting oviposition. Although preliminary, these interesting findings suggest that starches may have potential in managing development and reproduction of T. castaneum-a pest that is common and severe in food-processing facilities. Keywords : Nutritional control, Tribolium castaneum , Resistant starches, Development, Oviposition, Pest management