Biological Characteristics And Host Location Of Tetrastichus Planipennisi (Hymennoptera: Eulophidae)

Agrilus planipennis Fairmaire(Emerald ash borer,EAB) is an important destroyed wood-boring beetle attacking ash trees,and natural distributed northeast Asia.In recent years,it spread North America and Europe.At present,this pest outbreaks domestic and abroad,therefore,leads to enormous economic and ecology damage.T.planipennisi(Hymennoptera:Eulophidae),a new speices,is an important natural enemy endoparasitizing the larvae of Agrilus planipennis in northeast of China.In order to use natural enemies control EAB,the morphological,biological and host location behavior of T.planipennisi were studied.The mainly work and results of this paper are as follow:This wasp is a new effective natural enemy to EAB.It generally occured 3～4 generations one year in Changchun city and overwinters in the gallery bored by A.planipennis as a full-grown larva, and the generations overlaps heavily.Its natural parasitism rate was 35.72%in average,and the highest was up to 76.92%.The sex ratio of female to male was 2.39:1～5.06:1 in different periods and 3.04:1 in average.This wasp The female adults could live 16.2±1.24 days and 7.00±1.19 days for male in average when fed with 20%honey solution,with a maxium life span of 29 days.The effective accumulated temperature and threshold temperature for pupal development of T. planipennisi was studied,which were 78.851±0.442 degree-day and 16.823±1.381℃respectively, and corresponding regression equation was established:T=16.823+78.851V.These data were important in mass-rearing the wasp for biological control for emerald ash borer.Host selection behaviour of female wasps were investigated by Y-tube olfatometer.The results showed that the damaged bark,EAB larva,fecula inside EAB gallery all have certain degree of attraction.EAB fecula inside the gallery and host plant secondary volatile substance has strong temptation(P＜0.05),which may plays an important role in the process of the host positioning.Female wasps were tested by host lacotion behaviors and EAG electrophysiology behaviors and the host plant secondary volatile substances,which may play an important role when the wasps select host insects,were screen out.The wasps were attracted by different sources for the positive tendency and clean air(from high to low):damaged bark+fecula inside EAB gallery＞fecula inside EAB gallery＞damaged bark＞EAB larva＞healthy bark＞clean air,and were attracted by different sources for the positive tendency:damaged bark+fecula inside EAB gallery＞damaged bark＞fecula inside EAB gallery＞healthy bark＞healthy leaves.Using electron microscope(SEM) to the wasp antennae,which made a knee scan.Female wasp antennae generally has 10 sections which was about 814.51μm,and male has 9 sections which was about 838.39μm.The results showed that there were six types of sensilla in the adult antenna,i.e., placoclea sensilla,Finger sensilla,sensilla trichodea,sensilla chaeticea,sensilla ampullae and B(o|¨)hm's bristles.These differences in type,number and distribution between sexes provide a morphological basis for researching on the parasite discrimination and behavior of host selection. The male and female sensilla types and quantity differences,according to the microscopic structure, the writer conjecture the chemical function of these sensilla.