| Cryptolestes trucicus Grouville is a global stored-grain pest. In order to understand the population dynamics of C. trucicus and effective control methods, experimental population life tables were established at different temperatures.The control effect of plant essential oils and inert duston C. trucicuswereassessed, and the surface structure of C. trucicusbody was observed with scanning electron microscopy. Host preference of C. trucicuswas tested with Y-tube olfactometer. The main results are as follows.1. Influence of temperature on the growth and reproduction of C. trucicus At the range of 16? to 36 ?, the developmental period, survival rate and experimental population parameters of C.trucicuschanged with different temperatures, and the suitable temperature zone for the development and reproduction was 20?~32?, the most suitable temperature was 28? and 32?. While the population of C.trucicus decreased at 16? and 36?, its developmental time prolonged and the survival rate of immature stage decreased rapidly. In this experiment, the Logistic model was more suitable to describe the relationship between the developmental rate of C.trucicus and temperature than that of Linearmodel.2. Repellent activity and fumigant activity of plant essential oils against C. turcicus Repellent activity and fumigant activity of 34 kinds of plant essential oils against C. turcicus were assessed. The results showed that the cinnamon oil(Cinnamomum Cassia Presl) had the strongest repellent activity, which still had significant repellent activity after 72 h. While cumin seeds oil(Cuminum cyminum L.), pine oil(Pinus elliottii Engelm.), and black pepper oil(Piper nigrum L.) showed obvious attraction activity. The garlic oil(Allium sativum L.)and mustard oil(Brassica juncea(L.) Czern.et Coss.)had the strongest fumigant toxicity,and their control effect wereenhanced with the increase of concentration. Garlic oil had lower LC50 value than that of mustard oil at the the same exposure time,which showed stronger insecticidal activity.3. Control effect of inert dust against C.trucicus and its influence on the structure of body wall Inert dust mixed with wheatshowed strong contact toxicity to C. trucicus, and its control effectenhanced with the increase of the dose and the exposure time. The median lethal dose(LD50) of inert dust at 24 h, 48 h, 72 h were 0.0083 g/kg, 0.0056 g/kg and 0.0041 g/kg, respectively. Scanning electron microscope was used to observe the body surface structure of C.trucicus which was dealt with inert dust. The results showed that compared with control,the inert dust could attach to many parts of the body, such as back, abdomen, feet and antennas;A partof hairs in cuticula damaged and lost;Somite and related appendages joints, such as the part between head and prothorax, the part between prothorax and mesothorax, feet coxa nest, etc, had contracted distinctly.4. Olfactory response of C. trucicus to different stored grains Compared with control, female adults of C. trucicuscould be attracted to the tested stored grains,such as wheat, corn, little sweet buckwheat, oat, brown rice, yellow millet and sorghum. However, with whole meal as a control, the female adult's olfactory behavioral responses turn out to be different. When whole meal paired with the little sweet buckwheat and corn respectively, the experiment demonstrates that the test insects all tend to the whole meal. When the whole meal compared with the other types of stored grains, such as wheat, oat, brown rice, yellow millet and sorghum, the test insects showed no obvious preference. |
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