| Lasioderma serricorne(Fabricius)is one kind of important storage pests and it mainly damages tobacco,causing great loss to the tobacco industry in China.In order to explore the effects of different combinations of temperature,humidity and different host plants on the growth,development and reproduction of L.serricorne,two-sex life tables of L.serricorne experimental population were constructed.Based on population life table parameters,the population dynamics of L.serricorne in the longest life cycle were predicted.The results are as follows and they will provide theoretical basis to control L.serricorne.1.Effects of different temperature and humidity on growth,development and reproduction of L.serricorne.Different temperatures have a significant effect on the growth,development and reproduction of L.serricorne.The 1st instar larvae were all dead at 20℃,indicating the temperature below 20℃ is not suitable for the growth and development of L.serricorne.With the increasing of temperature,the developmental rate of L.serricorne accelerated and the eggs,larval and pupal durations gradually shortened under the temperature range from 24℃ to 32℃;however,the larval periods would be extended once the temperature above 32℃(at 36℃)because high temperature could inhibit the growth and development of larvae.With the increasing of temperature,the longevity of female adults was significantly longer and reached the longest at 32℃;The male adult longevity of L.serricorne reached the longest at 28℃ and then significantly shortened,indicating that high temperature was not beneficial for the survival of adults.There was no significant difference in the sex ratio of L.serricorne at four different temperatures,indicating that temperatures had no significant effect on the sex ratio of offspring.Both the oviposition period and the female fecundity gradually increased,however the oviposition period and female fecundity showed a downward trend once the temperatures were above 32℃(at 36℃).The fecundity of female adults was significantly different under 60%RH,70%RH and 80%RH,the number of eggs laid per female was the highest at 32℃,which were 101.89,80.63 and 68.32,respectively.Under three different humidities,the age-stage specific life expectancy(exj)was the highest at 24℃ and the lowest at 32℃.The age-age specific reproductive value(vxj)reached the highest at 32℃ and under the conditions of 60%RH and 80%RH,while it was highest at 24℃ and 70%RH.The net reproductive rate(R0)of L.serricorne would be the highest when under the condition of 32℃ and 60%RH or 70%RH,and they were 37.69 and 30.65,respectively;While the highest net reproductive rate(R0)only was 18.53 at 28℃ and 80%RH.The mean generation time(T)decreased significantly under the conditions of 60%RH,70%RH and 80%RH,the shortest value were 72.68 d,72.79 d and 62.80 d respectively at 32℃ and the longest were 151.06 d,128.92 d and 114.85 d respectively at 24℃.All the intrinsic rate of increase(r)of L.serricorne significantly increased as the tested temperature increased,and reached the highest at 32℃(0.0498,0.0468 and 0.0428,respectively)under three relative humidity conditions.The results indicated 32℃ is the optimum temperature for the growth,development and reproduction of L.serricorne.In order to explore the effects of different humidities on the growth,development and reproduction of L.serricorne,age-stage two-sex life tables of the experimental population of L.serricorne under the conditions of five different relative humidities(50±5%RH、60±5%RH、70±5%RH、80±5%RH and 90±5%RH)and at 32±1℃ and aphotoperiod of 14 L:10 D in the laboratory were constructed.The results showed that L.serricorne could not complete the development of one generation,the first and second instar larvae of L.serricorne would be dead under the conditions of 50%RH and 90%RH,respectively.However,L.serricorne could finish the development of one generation under the conditions of 60%RH,70%RH and 80%RH.No significant differences were found in egg duration except for the conditions of 70%RH and 90%RH.The larval duration of the 1st(8.08d),2nd(6.82d)and 3rd(7.05d)instar of L.serricorne under the condition of 80%RH were significantly shorter than that under the conditions of 60%RH and 70%RH.The longest life span of female adult is 25.84d at 60%RH,and the longest life of male adult is 15.25d at 80%RH.Adult pre-oviposition period(APOP)(2.55d),total pre-oviposition period(TPOP)(58.41 d)and oviposition period(7.00d)were the shortest at 80%RH,while no significant difference were found at 60%RH and 70%RH.Fecundity,age-stage life expectancy(exj),age-stage specific reproductive value(vxj)under three humidity conditions of 60%RH,70%RH and 80%RH have significant differences,which were the highest at 60%RH.With the humidity increasing,the net reproduction rate(R0)decreased under three humidity conditions of 60%RH,70%RH and 80%RH,they were 37.69,30.65 and 15.02,respectively.The intrinsic rate of increase(r)and the finite rate of increase(λ)had no significant differences under three humidity conditions,were 0.05,0.05,0.04 and 1.05,1.05,1.04,respectively.There were no significant difference on the generation time(T)(72.68d and 72.79d)under 60%RH and 70%RH,but was significantly longer than that of 80%RH(62.80d).The results of prediction for L.serricorne population showed that the lowest larval number were found in 60d,50d and 38d,then the population started to explosion,indicated preventive measures should be taken before this period.The best combination of temperature and relative humidity condition was 32℃ and 60%RH.2.Effects of different host plants on growth,development and reproduction of L.serricorne.Different host plants had significant influence on the growth and reproduction of L.serricorne.The results showed that L.serricorne reared on three host plants at 20℃ failed to complete the development of generation,and it was not able to develop,survive and reproduce successfully on honeysuckle at 36℃.The developmental duration of each stage reared on tobacco were significantly longer than that of L.serricorne reared on honeysuckle or chrysanthemums at 24℃,28℃,32℃ and 36℃ under laboratory conditions.The adults pre-oviposition period(APOP)of L.serricorne were 2 to 3 days,except that reared on chrysanthemums and tobacco at 24℃(more than 3 days).The fecundity of female adults when reared on tobacco was significantly higher than that reared on other two host plants,and the number of eggs laid per female at 24℃,28℃,32℃ and 36℃ were 46.33,63.86,68.32 and 23.08,respectively.Both the age-stage specific life expectancy(exj)and the age-age specific reproductive value(vxj)of L.serricorne reared on tobacco were significantly higher than that of L.serricorne reared on honeysuckle and chrysanthemum.The net reproductive rate(R0)of L.serricorne reared on honeysuckle was the lowest,while its mean generation time(T)was the shortest;the value of net reproductive rate(R0)of L.serricorne reared on tobacco at 24℃ and 36℃ was significantly smaller than that of L.serricorne reared on honeysuckle and chrysanthemum,while R0 of L.serricorne reared on chrysanthemum was significantly higher than that of L.serricorne reared on honeysuckle and tobacco at 28℃ and 32℃.The mean generation time(T)of L.serricorne reared on tobacco was significantly longer than that reared on honeysuckle and chrysanthemum;however,there was no significant difference in mean generation time(T)of L.serricorne when feed on chrysanthemum and tobacco at 36℃.The intrinsic rate of increase(r)and finite rate of increase(λ)of L.serricorne reared on chrysanthemum were significantly higher than that of L.serricorne reared on honeysuckle and tobacco at 24℃,28℃,and 32℃,they were 0.0231,0.0553,0.0654,respectively and 1.0233,1.0569,1.0676,respectively.Based on the results of population prediction,it could be found chrysanthemum and tobacco were more suitable as hosts of L.serricorne at 24℃,and chrysanthemum could replace tobacco and become the most suitable hosts at 28℃ and 32℃,while only tobacco could be used as a suitable host plant for L.serricorne at 36℃.The above results indicated that the best combination of host plant and temperature condition was chrysanthemum and 32℃. |
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