| Cryptolestes ferrugineus(Stephens)(Coleoptera: Laemophloeidae), also called rusty grain beetle, is a worldwide pest of stored grain and one of the most difficult pests to be controlled currently. To ecological control of this pest, the effect of temperature on the development and fecundity of C. ferrugineus were discussed in this paper. The repellent activity and fumigant toxicity activity of 23 plant essential oils on C. ferrugineus adults were tested, and two effective essential oils were chosen to determine their fumigant toxicity effects under different concentration and time gradient. The insecticidal activity of inert dust was also measured, and the epicuticula ultrastructures of C. ferrugineus were observed with Field-Emission-Scanning-Electron-Microscopy(FESEM). Finally, the control effect of essential oil combined with the inert dust was evaluated. The main results are as follows.1. The larvae of C. ferrugineus could not develop to adults at 16? and 20?. While C. ferrugineus could finish its generation development at 24?, 28?, 32? and 36?, their generation development time were 126.69 d, 81.18 d, 49.31 d and 39.96 d, respectively. And the highest survival rates of most stage of C. ferrugineus were observed at 32?. No obvious oviposition peaks were observed at 24? and 28?. However, there were peaks at 32? and 36?. Althought the highest daily egg product appeared at 36?, the oviposition period was much longer at 32? than those at 36?, and so did the total fecundity. According to the survival rate and fecundity, it could be concluded that 32? was the optium temperature for C. ferrugineus population within the test temperature range.2. Among 23 essential oil, Allium sativum essential oil,Cymbopogon citratus essential oil,Alpinia katsumadai essential oil and Perilla frutescen essential oil showed good repellent effect on C. ferrugineus adults, while the other 19 kinds of essential oils had inconspicuous performance.Brassica nigra essential oil, A. sativum essential oil, Ilex chinensis essential oil, Cinnamomum camphora essential oil, Mentha spicata essential oil and Eucalyptus globulus essential oil showed evident toxicity activity to C. ferrugineus. The corrected mortality reached more than 90% at 20?L/L·100g-1 dose after 48 hours. Further, when the dose decreased to 10?L/L·100g-1, the corrected mortality of B.nigra essential oil and A. sativum essential oil to C. ferrugineus still kept in 100%. Different concentration gradient and time gradient were set to determine the fumigant toxicity of B.nigra essential oil and A. sativum essential oil. The LC50 of C. ferrugineus fumigated by the essential oils of A. sativum essential oil under the exposure time of 24, 48 and 72 hours were 0.7827, 0.7222 and 0.6478?L/L·100g-1, respectively. While the LC50 of B. nigra essential oil under the same exposure time were 2.7581, 2.6117 and 2.4619?L/L·100g-1, respectively. The fumigant toxicity of A. sativum essential oil on adults of rusty grain beetle was stronger than that of B. nigra essential oil.3. The insecticidal activity of inert dust to C. ferrugineus adults was tested under different concentration gradient and exposure time. The result showed that inert dust had strong insecticidal effect though in a very low dose. The LD50 were 0.0042, 0.0028 and 0.0025g/100 g when exposured after 1, 3 and 7d, respectively. The epicuticula ultrastructure of C. ferrugineus adults was observed with FESEM. Compared with the Control, inert dust adhered to every segmacoria and coxal cavity on the body of C. ferrugineus adult. Some other significant differences were also found in the epicuticula ultrastructure treated with inert dust.4. B.nigra essential oil and A. sativum essential oil combined with inert dust could enhance their fumigant toxicity effect obviously. The LC50 of B. nigra essential oil combined with inert dust under 1,2,3 and 7 days were 1.7844,1.3403,1.1207 and 0.9581?L/L·100g-1, respectively. While the LC50 of A. sativum essential oil under the same condition and exposure time were 0.4351,0.2393,0.1459 and 0.0480?L/L·100g-1? So application amount of B.nigra essential oil and A. sativum essential oil could be reduced by 1/3 to 2/3. |
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