A Research On Biological Characteristics And Prevention Of Plecoptera Bilinealis Of Dalbergia Odorifera

Plecoptera bilinealis,belonging to lepidoptera,cutworm,the larvae is one of which mainly damages Precious tree of dalbergia odorifera.In recent years,Plecoptera bilinealis harm seriously,but the biological characteristics and occurrence regularity and pollution-free control research has never been carried out.To understand the occurrence regularity accurately,to develop Scientific prevention and control strategy,this article mainly study the biological characteristics and occurrence regularity and pollution-free control of Plecoptera bilinealis,including morphologic characteristic,behavior,the years life history,larval age,population dynamics and happening regularity,the influence for the growth and development for Plecoptera bilinealis of the different temperature,the different humidity,the different light cycle;Combing laboratory with field observation,identification of instars of larve of Plecoptera bilinealis,the development threshoid temperature and effective accumulative temperature of Plecoptera bilinealis were studied under constant temperatures in the laboratory,toxicities of 5 kinds of insecticides to larvae were determined by residual film with filter paper method,and the effect in the field of 5 kinds of insecticides was also tested.The main results were stated briefly as follows:1?The biological characteristics of Plecoptera bilinealis(1)Morphologic characterEggs:ellipsoid,egg grain stack,egg surface is covered by light yellow hair material;Larvae:larvae has three pairs chest foot,early color is light green,then the color become to dark green,mature larvae' color is purple;Pupa:conical,the head is larger,the tail is pointed,the pupa is red-brown;Adult:siphon mouthparts,the head is small,with a pair of big brown compound eye.The cephalothorax is covered with brown hairs,the positive is gray or brown.The tentacles is filiform,the wings is gray-brown,The shape of wings is arc,brown hair.(2)Behavior habitsFeeding habits:The young larvae feeds egg shell and the mesophyll which is around of the egg shell,1-4 of age's larvae eat less,after 4 age of the larvae are into overeating,the larvae like eating leaves,often produce silk to hang its body;Spawning habits:the adult begin to lay eggs after two days when they mated,the eggs are layed surface of the leaves,eggs were covered with a layer of pale yellow velvet;Pupation habits:the mature larvae like pupation in dark environment,overwintering pupa is covered in soft soil or earth shell,the non-overwintering pupa often pupated in the back of the leaves.Feather habits:About 30?50 min is used from the pupa broken to adult worms crawl out.Wings fully opened cost about 15?20 min.(3)Life historyThe Plecoptera bilinealis happen three non-overlapping generations a year in Chengmai region.Larvae begin to pupate after mid-October,overwintering pupa begin to feather until in mid-march of the following year.(4)Identification of instars of larvaThe results showed that the Plecoptera bilinealis have six instars.The average proportions of every two head-width of neighboring instars is 1.45 times.2?Field Population Fluctuation PatternsThe larvae of Plecoptera bilinealis occurred from March to October.Larvae damage peak in mid-may,in mid-july,and early September.The larvae begin to pupate after mid-October.3?The effect of the environmental factors on the growth and development of Plecoptera bilinealis(1)The effect of the temperature on the growth and development of Plecoptera bilinealisIn the range from 24? to 32 ?,the durations of various stages were shortened with the increase of temperature,34?-35? is the death temperature of 1-4 instars,35?-37? is the death temperature of adult.(2)The effect of the humidity on the growth and development of Plecoptera bilinealisWhen the relative humidity was 65%RH—85%RH,as the increase of humidity,the eggs,larvae and pupae development period became shorten before they were extented,but the early of Plecoptera bilinealis and one generation development period became shorten.(3)The effect of the photoperiod on the growth and development of Plecoptera bilinealisWith the increasing of age insect,the effect of the photoperiod becomes more and more obvious;as the increase of the illumination time,the overwintering pupae development period obviously prolonged,but the changed photoperiod had a litter effect on non-overwintering pupa development period.4?pollution-free control(1)Toxicities of 5 kinds of insecticides to larvae were determined in doorThe toxicities of 5 kinds of pesticides on larvae from big to small in turn is iacetamiprid,abamectin,emamectin benzoate,beta-cypermethrin and imidacloprid.imidacloprid relative toxicities is more than imidacloprid 22.4 times.(2)Five kinds of insecticides agent field efficacy trialsThe results show that,10%iacetamiprid WP,1.8%abamectin EC,5%emamectin benzoate WG,30%trichlorfon EC and 4.5%beta-cypermethrin EC had achieved good prevention and cure effect,and they showed good readily availability,but 5%imidacloprid EC showed bad effect.1.8%abamectin EC,5%emamectin benzoate WG had a good effect.