The Biological Characteristics Of Pediobius Yunnanensis Liao And Its Parasitism To Dioryctria Rubella Hampson

Pediobius yunnanensis Liao is an important endoparasitic wasp parasitic to the pupa of Dioryctria rubella Hampson.However,its biological characteristics have not been reported.In this paper,the biological characteristics,the influence of temperature on the parasitic,growth and development of P.yunnanensis Liao,and the parasitic effects of P.yunnanensis Liao on D.rubella Hampsoni were studied by combining field investigation and laboratory tests.The main results are as follows:1)The basic biological characteristics of P.yunnanensis Liao.The male and female morphology of the P.yunnanensis Liao is similar,the male is slightly smaller than the female,and the abdomen is almost completely hidden under the first abdominal segment.The P.yunnanensis Liao mainly overwintered as larvae in the pupa of the host.The average sex ratio of male to female wasps was 1.89:1.At 25?,the P.yunnanenis Liao develops into an adult through eggs,larvae and pupae,with a generational period of 30 to 37 days.The emergence time of adults were 4 d,and the emergence time was mainly concentrated in the two time periods of 0:00?6:00 and 20:00?22:00.The emergence rate is 95.81%.The female could mate and lay eggs on the day of emergence,and the mating time was 8?20s.Parthenogenesis and hermaphroditism can lay eggs and complete generation development,but parthenogenesis offspring are males.Supplementation of different nutrients can prolong the life of adults in different degrees,especially after supplementation of 15%honey water.In addition,hosts that can be parasitized by the P.yunnanensis Liao are the D.rubella Hampson,Dioryctria pryeri,Rhyscionia pinicolana(Doubleday)and Pyrausta nubilalis Hubern.Their parasitic rates are 76.91%,70.00%.66.67%,and 15.38%,respectively.The emergence number of P.yunnanensis Liao was 81,105.43 and 32,respectively.The above research results can provide guidance for the biological control of the D.rubella Hampson,and also provide a certain theoretical basis for the research and development of indoor breeding and protection and utilization technology of the P.yunnanensis Liao.2)Effects of temperature on the parasitic,growth and development of P.yunnanensis LiaoThe effects of different temperatures(15,20,25,28,30,33,and 35?)on the parasitic rate and growth of P.yunnanensis Liao were studied.The results showed that at 15 and 35?,the parasitic rate of P.yunnanensis Liao is 0.At these two temperatures,the P.yunnanensis Liao cannot establish a parasitic relationship with the host.In the range of 20?33?.the P.yunnanensis Liao can establish a parasitic relationship with the host and complete the generational development in the host pupa.At 30?,the parasitic rate is 81.82%t.The developmental period of each stage of P.yunnanensis Liao shortens with increasing temperature.And the developmental threshold temperatures of egg-larva,pupa,adult,host intra pupae generation and whole generations were 15.83,12.78,15.48 and 1 5.05?,respectively.The effective accumulated temperatures were 127.05,144.14,55.80 and 3 14.15 degree days respectively.The number of generations of the P.yunnanensis Liao is from north to south,and it gradually increases from west to east.It can occur in the D.rubella Hampson hazard area in China for 2 to 9 generations.3)The parasitic effect of P.yunnanensis Liao on the D.rubella HampsonThe scent of Pinus tabulaeformis with D.rubella Hampson has a significant attracting effect on P.yunnanensis Liao,but the healthy pine branch has no attracting activity.At close range,the organic extracts that larvae's dung,cocoons,and pupae of D.rubella Hampson have obvious appeal to the parasitoid.The P.yunnanensis Liao can lay eggs on the head,chest,and abdomen of the host,but mainly on the chest.The P.yunnanensis Liao favors the selection of parasitic reddish spotted salamanders with a parasitic rate of 76.19%.The number,developmental period and individual size of the offspring of parasitic wasps increased and decreased with the age of the host.Under the same age conditions of host pupae,the parasitic number of P.yunnanensis Liao increased as the host pupae density increased.When the number of hosts increases to a certain degree,the amount of parasites does not increase,and its parasitic function response fitted with Holling type II.A single female can parasite up to 14.03 host pupae within 24 hours.The time required to parasite a pupa is 0.0713h.and the instant attack rate is 0.9365.When the self-density was 3,the parasitic rate to the pupa was the highest(80.00%).