Study On The Growth,Development And Reproductive Characteristics Of Delphastus Catalinae(Horn) Feeding On The Eggs Of Ephestia Kuehniella Zeller

Bemisia tabaci is a world-wide important pest that caused significant losses to agricultural production.Delphastus catalinae(Horn)is an important predatory natural enemy of B.tabaci imported from abroad.Its artificial scale expansion can not only enrich the natural enemies,but also have important significance in achieving sustainable control of B.tabaci,reducing the use of chemical pesticides,and protecting the ecological environment.In this thesis,the effects of Ephestia kuehniella Zeller eggs on the growth and development of D.catalinae,adult reproduction,sex ratio,ovary development,and control of whiteflies were studied.The research results will provide a theoretical basis for the artificially large-scale reproduction of D.catalinae.The main conclusions are as follows:1.After feeding on E.kuehniella eggs,third and fourth instar larvae of D.catalinae could survive.The developmental duration of the third-instar larvae(3.71d)was significantly longer than that of feeding on B.tabaci eggs(2.00d)continuously;the survival rate of each instar period was lower than that of feeding on B.tabaci eggs(2.00d)continuously,and the difference between the survival rate of the third-instar larvae is extremely significant;the pupation rate(96.43%)and adult eclosion rate(73.81%)were lower than that of feeding on B.tabaci eggs continuously.There were no significant difference between the adult weight and male-to-female ratios.Since the fourth instar larvae was fed on E.kuehniella eggs,there had significant difference in the developmental duration of each stage of D.catalinae.The longest period is 5.75d and the shortest period is 2.42d.The difference was not significant when compared to D.catalinae that was fed on B.tabaci eggs from the fourth instar larvae.The differences were significant in survival rate except pre-expiration period(100.00%)and pupae period(88.00%).The ratio of pupation(94.18%)and adult emergence(86.01%)of fourth instar larvae were lower than that of feeding on B.tabaci eggs continuously.There was no significant difference in male and female sex ratios and weights.Among them,the average female weight of the former is 0.36mg,and the average male weight is 0.22mg.The average female weight of the latter was 0.37mg,and the average male weight was 0.35mg.2.After feeding on E.kuehniella eggs,the average life span of male and female D.catalinae was not significantly different from that of male and female D.catalinae feeding on whiteflies continuously.The longest lifespan of D.catalinae feeding on E.kuehniella eggs was 160d,and the longest lifespan for feeding on B.tabaci eggs was 167d.It was found that the difference in the pre-mating period of D.catalinae feeding on different eggs was extremely significant.The pre-mating period(10.63d)of D.catalinae feeding on E.kuehniella eggs was longer than that(8.08d)of feeding on B.tabaci eggs.For the average daily fecundity of D.catalinae feeding on different eggs at different mating times,there was no significant difference between one mating but there had significant differences between 2 and 3 mating times,and multiple mating times.For the pre-spawning period,there had no significant difference in the mating of D.catalinae feeding on different eggs,and there had significant differences between the 2 and 3 mating times.In addition,D.catalinae feeding on E.kuehniella eggs were older than that feeding on B.tabaci eggs at different mating times.When D.catalinae was fed on B.tabaci eggs after being fed on E.kuehniella eggs for 21 days,there were no significant differences in daily fecundity and total fecundity.3.Female ovary of D.catalinae feeding on E.kuehniella eggs were dissected in continuous 30 days,the ovarian development was slower and the yolk deposition was later compared to the females that were fed on B.tabaci eggs,but still mature.This might be one of the reasons for the prolonged pre-oviposition period and the lower daily fecundity of D.catalinae that feeding on E.kuehniella eggs.For D.catalinae feeding on E.kuehniella eggs,the yolk deposition began to appear on the 8th day and maturated on the 14th day after emergence;while for D.catalinae feeding on whiteflies,the yolk deposition began to appear on the 2nd day and maturated on the 6th day after emergence.4.Both D.catalinae feeding on E.kuehniella eggs or B.tabaci eggs could control B.tabaci.The survival rate of B.tabaci in the release zone was significantly reduced,the final population of the next generation was 4.33 and 5.03 times than that of the previous generation respectively.By EIPC analyzing,the predation of D.catalinae was the most important lethal factor.The EIPCs of releasing D.catalinae feeding on E.kuehniella eggs or B.tabaci eggs were 7.19 and 6.20 respectively.If this factor was excluded,the population growth trend index of B.tabaci would increase by 7.19 and 6.20 times respectively.