The Effects Of Feeding Response And Growth And Development Of Lygus Pratensis On Different Host Plants

It is the largest production base of commodity cotton in Xinjiang of China.The cotton yield accounted for more than 50% of national yield in 2014.In recent years,Helibthis armigera is made effective control with transgenic insect-resistant cotton planting,but piercing-sucking injurious insects such as cotton capsid is gradually becoming the main pest with chemical usage gradually reduced.Lygus pratensis is dominant specie with a percentage of 99.93% in total number in Xinjiang.The current research focuses mainly on the biological characteristics,occurrence regularity and control technology,but it has not been reported on the damaged host physiological indicators.In this paper,The physiological index change of damaged host and growth and development of Lygus pratensis to different host plants were studied in order to understand the interaction relationship between different hosts and Lygus pratensis to provide theoretical basis for prevention and control the pest.The results are as follows:1 The physiological responses of cotton to Lygus pratensis feedingThe chlorophyll contents were decreased and the decrease rate of Xinluzhong38 was 18.34%,but there was no significant difference with the control group.The soluble sugar content increased by 30% and the difference was significant.The content of free proline was on the rise and the content change of damaged Xinluzhong38 was prominent with the rate of 36.73%.The protein contents of different varieties were decreased and the change rate of Xinluzhong37 was up to63.94% and the difference was significant than normal.The POD activity was increased and the difference was significant.The decrease rate of CAT activity of Xinluzhong37 and Xinluzhong38 was 55% and the decrease rate of j206-5 was 30%.SOD activity increased,but there was no significant difference with the control2 Effect of physiological indices of host plants after the damage by Lygus pratensisChlorophyll content in different hosts were decreased after the damage by Lygus pratensis,in which Amaranthus retroflexus was the lowest(2.6%),but the content of Medicago sativa decreased the most(26.21%).The change of soluble sugar content was varied,among which Kochia prostrata declined the highest(24.05%).It was a significant difference compared with the contrast.The soluble sugar content of Chenopodium glaucum increased by 68.92%,with the significant difference between the contrast and the samples.In addition,the content of free proline in leaves of Amaranthus lividus L.The content of free proline showed an increasing trend except that of Amaranthus lividus,it decreased by 38.87%.The protein content was decreased,which Amaranthus lividus was the lowest(2.96%).The POD activity of different host showed an increasing trend after the damage.POD activity of Portulaca oleracea increased the highest,reaching 74.23%.The CAT activity was Variation after the damage,Chenopodium glaucum,Medicago sativa and Convolvulus arvensis reaching by 45.07%,30.95% and 22.47% respectively.CAT activity of Portulaca oleracea L.and Medicago lupulina L.decreased significantly after the damage.The SOD activity was increased after the damage,but no significant difference was found.It is further indicated that changes of chlorophyll content and free proline content were wellcorrelated with the preference of Lygus pratensis and soluble sugar,protein content and protective enzyme activity were irregular or had no significant difference.It was not able to judge the degree of preference of Lygus pratensis.3 Effects of growth and development of Lygus pratensis on different host plantsThe growth period of forage staeg of Lygus pratensis was the shortest,16.56 d and 17.60 d respectively and had the highest survival rate,76% and 74% respectively when they feed Brassica oleracea and green beans.The longest growth period was to feed Convolvulus arvense,which was22.12 d and the survival rate was only 35%.The maximum weight on feeding Brassica oleracea and green beans was 0.083 g and 0.069 g respectively.Lygus pratensis were feed in door by nine different hosts and larvae were hatched only on feeding Brassica oleracea and green beans.Therefore,the most suitable host plants were Brassica oleracea and green beans,but the lowest one was Convolvulus arvense.