Physiology of cold tolerance of Trogoderma granarium Everts (Coleoptera: Dermestidae) reared on different diets
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Supercooling point and cold hardiness of Trogoderma granarium on ten diets (barley, corn, millet, rice, rye, sorghum, triticale, wheat groundnut, and walnut) were studied under laboratory conditions (33±1 °C with 65±5% RH, 14L: 10D). According to results, significant differences in total body sugars of T. granarium larvae were detected among the different diets. Glycogen content was at a high level in larvae fed on different diets and ranged from 34.2±1.3 in sorghum to 94.7±8.8 µg/larva in rye. In addition different diets showed a significant effect on whole body lipid content of larvae, which was at the highest level on triticale (585.9±41.6 µg/larva) and rye (558.0±32.4 µg/larva), and lowest level on sorghum (167.4±11.1 µg/larva). Three main low-molecular-weight carbohydrates in larvae fed on different diets were found to be trehalose, sorbitol and myo-inositol, although glucose was present in whole body extracts of larvae fed on groundnut, walnut and corn. Records for the highest level of trehalose were on triticale (22.02±1.69 µg/larva), groundnut (20.52±1.14 µg/larva) and rye (19.04±0.96 µg/larva). By contrast, records for the lowest level of trehalose were on barley (9.29±0.90 µg/larva) and sorghum (6.79±0.65 µg/larva). The level of sorbitol fluctuated greatly across larval diets, reaching its highest concentration on rye (3.90±0.16 µg/larva). The larvae reared on wheat (10.44±0.24 µg/larva) and walnut (9.51±0.74 µg/larva) had the highest level of myo-inositol, and those on rice (6.82±0.47 µg/larva), rye (7.29±0.15 µg/larva), sorghum (7.55±0.17 µg/larva) and millet (7.80±0.43 µg/larva) had the lowest level of myo-inositol. The supercooling point of larvae reared on triticale was -20.59±0.52, -20±0.5 °C, and significantly lower than other diets. Exposures to –5 and –10 °C are somewhat endured by larvae fed on triticale, rye, walnut, and groundnut whilst exposure to –20 °C caused 100% mortality in these groups. These results suggest that larval food quality can affect biological and physiological characteristics and influence the supercooling point and cold hardiness of T. granarium.
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