Bionomics Of Encarsia Sophia (Girault & Dodd)

As an important insect pest in the world,Bemisia tabaci(Gennadius)once caused great losses on agricultural production in the United States,Brazil and other countries and over 20 different biological types have been reported so far.B-type B.tabaci is an invasive pest species and flowers, fruits,vegetables and other lots of economic crops are its hosts.This insect has caused enormous economic losses in China's agricultural production since the late 1990s' invasion into China.In Beijing,much damage has been brought in the yield of cucumber,tomato,eggplant,summer squash, and melon plants,and sometimes even over 70%of the yield was lost.A broad host spectrum and high resistance characteristics have stimulated the pest's rapid spread.Among different control measures,the biological control has been the focus and there were a lot of research about the species of wasp Encarsia,the parasitic natural enemies for B.tabaci.Encarsia formosa Gahan has been successfully applied in the biological control of whitefly.The biological characters of Encarsia sophia(Girault & Dodd)were studied here.The wasp originated in India and there is a promising prospect of the insect on biological control of whitefly. On the basis of the establishment of the laboratory populations of E.Sophia,the biological characteristics of the wasp hosted by the nymph of tobacco whitefly was investigated in detail,and the results were as follows:(1)The tomato plant was finally selected as the host plant one the premise of a comprehensive evaluation of the advantages and disadvantages over effect on whitefly by host of beans,cucumber, cabbage,tomato,cotton,and sweet potato.Two population breeding methods of "micro-law of insect cage" and "whole-petri dish" were designed and evaluated,more convenient and practical of the latter in the practical operation.The fact that E.sophia is a solitary,arrhenotokous, heteronymous,autoparasitoid was also verified.(2)The study of major behaviors(emergence,mating and oviposition)of E.sophia revealed that there was an emergence rate of 98±0.64%and emergence occurred any time with obvious rhythm.The emergence peak concentrated in the morning between 08:00 to 12:00,accounting for 58%and lasting 14 to 29 min.Male and female wasps could mate after mating without food,male mated with female many times and female mated only once and then oviposited in its life.Through oviposition record and observation,the laying process could be divided into four procedures:host location,host examination,eggs puncture and cleaning.(3)The experimental population life table of E.Sophia was constructed.Six stages of E.sophia were listed as:egg stage(1.90 d),1st instars(1.05 d),the 2nd instars(1.02 d),3rd instars(2.21 d), perusal stage(0.78 d)and black pupal stage(5.70 d).The measure values of various developmental stages of wasps showed that a continuous increase in wide trend and the longest body was observed in 3rd nymph.There was an average adult longevity of 21.9 d.Generally speaking,every female lays one egg per host body and no matter how many eggs laid in one host can only emerge one adult bee. A detailed observation and description on the developmental stages were also carried out.Erery female laid 79.08 eggs in the whole life.Life table parameters were listed as 42.43 for the net reproductive rate R₀,18.94 for mean generation time T,0.20 for intrinsic rate of increase r_m,1.22 for finite rateλ,3.47 for the population doubling time and 43.33 for population trend index I.