Study On Biological Characteristics And Antioxidant Systems To Temperature Stress Of Darna Trima(Moore)

Drana trima(Moore)is one of primary pests appearing in tea gardens.They are mainly distributed in Taiwan,Fujian,Guangdong,Guangxi,Guizhou,Sichuan,Chongqing,Hunan,Jiangxi,Zhejiang and Anhui in China.They are also distributed in Southeast Asia and Indonesia.There is quite limited information about D.trima and therefore it is necessary to make numerous fundamental researches to develop effective and compressive control measures.The author observed basic morphological characteristics of D.tri,ma larvae in the laboratory and investigated their distribution and harm symptoms in the field,with the goal of providing more biological characteristics of D.trima.In order to research response mechanism of D.trima to temperature stress,the author determined activity of SOD,POD,CAT,GST and T-AOC in the body of the larvae at different temperatures and for different durations of temperature stress.The results are presented as below:(1)Firstly,the author observed morphological characteristics of D.trima larvae.The observation results show that,young larvae are canary yellow with brown streak.Growing larvae are oval and milk white with the front end a little wider and have a broad sepia area on the back from vertex to the end of abdomen.Mature larvae have a big dumbbell-shaped brown streak along the back and have 3 light longitudinal lines,4 white spots at front and rear end respectively as well as 2 rows of spines on their back,in which the outside row is a little longer.(2)The author also investigated distribution of the larvae in the field.According to the results,D.trima mostly present an aggregated distribution in tea bushes.They are distributed mainly by population;however,populations are mutually exclusive.Such an aggregated distribution stems from their biological characteristics and environmental factors of tea gardens.There is a significant difference in distribution on different layers of tea crown.Most of them aggregate at the lower part near the ground and a few at the middle part or top of crown.Population density of D.trima in Sichuan tea group,Nanjiangl and Yuchal also differs greatly.Specifically,the population density in Sichuan tea group is the highest and that in Nanjiangl is the lowest.Their distribution on tea bushes also differs greatly with instar.For Sichuan tea group,the highest population density appears in the fifth and sixth instar,while for Nanjiangl and Yuchal,the highest population density appears in the fourth and fifth instar.(3)Additionally,harm symptoms of D.trima were also observed.The results show that,D.trima mainly harm mature leaves and old leaves of tea at larva stage.The larvae totally have 9 instars.The first instar larvae do not eat;the second and third instar larvae only eat lower epidermis and mesophyll with the upper epidermis left and thus transparent spots form;the fourth instar larvae start to eat the upper epidermis and lead to holes in leaves;the fifth instar larvae cause incomplete edge of leaves or even eat up the whole leaves and move to the branches and roots;the eighth and ninth instar larvae move underneath roots or into the soil to cocoon and pupate.(4)Activity of four protective enzymes and total antioxidant capacity of D.trima were determined after application of different temperature stresses and different durations.The results show that,SOD,POD,CAT and GST activities were at a higher level when Drana trima were exposed to-50? for 2 h,among them,SOD,POD and CAT activities reached the maximum value,the values are 277.60 U·mg-1 protein,37.19U·mg-1protein and 43.35 U·mg-1protein,respectively.The values of GST is 81.74U·mg-1protein.T-AOC activity were at a higher level when Drana trima were exposed to 5 ? for 2 h,the value was 23.62U·mg-1protein.The experimental result indicated that there were other antioxidants to resist the damage of Reactive oxygen species in Drana trima.SOD,POD,CAT,GST and T-AOC activities were at a higher level when Drana trima were exposed to-5?,0?and 5?.SOD activity was significantly higher than comparison(26 ?)when Drana trima were exposed to-5?,0? and 5? for 4 h and 6 h.CAT activity was significantly higher than comparison(26 ?)when Drana trima were exposed to-5?,0? and 5? for 2 h.POD activity is significantly higher than comparison(26 ?)when Drana trima were exposed to-5?,0? and 5? for 6 h.GST activity was significantly higher than comparison(26 ?)when Drana trima were exposed to-5?,0? and 5? for 4 h and 6 h.T-AOC activity was significantly higher than comparison(26?)when Drana trima were exposed to-5?,0? and 5? for 6 h.The experimental result indicated that SOD,CAT,POD and GST activities increased to remove the Reactive oxygen species in Drana trima under the low temperature stress,so they could protect the body from low temperature damage.However,high temperature(-5?,0? and 5?)stress had little effect on SOD,CAT,POD,GST and T-AOC,and activities were at a lower level.The experimental result indicated that high temperature stress had little effect on antioxidants in Drana trima.