Biological Control Of Bemisia Tabaci,Trialeurodes Vaporariorum And Plutella Xylostella And Their Impact On Demographic And Fitness Traits Of Predatory Bug Orius Strigicollis Poppius

Invasive insect pests can significantly disturb native insect communities and cause considerable damage to agriculture and forests.Among these pests,whiteflies?Hemiptera:Aleyrodidae?and diamondback moth?Plutella xylostella L.??Lepidoptera:Plutellidae?are the most damaging insect pests to cultivated crops globally,including China.The polyphagous predatory bugs of genus Orius prey on a broad range of arthropods.Among these species,Orius strigicollis Poppius?Hemiptera:Anthocoridae?is a common and effective natural enemy present in cultivated fields of China and is used as a biological control agent against many small pests of economically important crops.The development and reproductive performance and fitness of a predator to particular prey highlight their potential as an active biological control agent.The type of food/prey and temperature fluctuations dramatically affect the biological and demographic parameters of a predator.In the present study,we evaluate the fluctuations in predatory behavior and life table traits of O.strigicollis fed on different prey species at different temperatures.Moreover,the age-stage Twosex life table technique was used to evaluate the performance of O.strigicollis as a biological control agent.The main results are as follows:1. The predatory functional response of Orius strigicollis?Hemiptera:Anthocoridae?fed on two whitefly species at different densitiesIn this study,the functional response of third instar nymphs and three days old adult female of O.strigicollis was studied under laboratory conditions against six different?4,6,8,10,12 and 14?densities of thirds instar nymphs of both whitefly species.The results showed a type II functional response for each life stage of O.strigicollis when fed each whitefly species.The calculated handling?Th?time for both life stages of O.strigicollis was short?1.75 h and 2.44 h?against third instar nymphs of Trialeurodes vaporariorum as compared to Bemisia tabaci?2.16 h and 2.45 h?.However,the coefficient of attack rate?a?was higher when third instar nymphs and adult females of O.strigicollis fed on B.tabaci compared to T.vaporariorum nymphs.The functional response parameters indicate that nymphs of T.vaporariorum were more voraciously killed by each life stage of O.strigicollis and therefore,O.strigicollis could serve as a useful and symbolic biological control agent against T.vaporariorum.2. Life table study and predatory potential of Orius strigicollis fed on Bemisia tabaci and Trialeurodes vaporariorum at a constant temperatureIn this study,the age-stage,two-sex life table technique was used to investigate the biological traits of O.strigicollis when presented third instar nymphs of two whitefly species as prey.The obtained results showed that the nymphal development of O.strigicollis was significantly shorter when fed Bemisia tabaci than Trialeurodes vaporariorum nymphs.Additionally,the total pre-oviposition period of adult females was statistically shorter when fed B.tabaci nymphs than T.vaporariorum nymphs.Furthermore,the survival rates and total fecundity of O.strigicollis were higher when fed B.tabaci than T.vaporariorum.There were no significant differences in any population parameters of O.strigicollis when fed either whitefly species.These results show that O.strigicollis could survive and maintain its populations on both species of whitefly and could,therefore,serve as a biological control agent in integrated pest management?IPM?.3. Daily predation,biological parameters,and survival of Orius strigicollis fed on eggs of Plutella xylostella at two constant temperaturesThe type of food and temperature intensely affect the biological and demographic parameters of Orius species.Thus,this study was performed to evaluate the effect of different temperatures on predation activity and fitness traits of O.strigicollis when fed on eggs of P.xylostella in climate chambers at 28 and 32±1 ^oC,70%R.H and 16:8photoperiod using age-stage Twosex-MSChart.The results showed that the daily egg consumption rate of the pre-adults of O.strigicollis was highest at 28 ^oC,and at this temperature,the nymphal survival was also maximum with reaching?42.5%?nymphs to the adult stage than at 32 ^oC?25%?.The longest oviposition period?9.38 days?,the highest female fecundity?42 eggs/female?,and the highest intrinsic rate of increase(r:0.087 d^-1)also occurred at 28 ^oC.The life expectancy(e_xj)of O.strigicollis was also highest at 28 ^oC?16.96 days?.Our results showed that temperature fluctuation noticeably disturbs the biology of O.strigicollis.Moreover,the predatory bug successfully develops survival and maintained its population on eggs of P.xylostella at 28 ^oC and could,therefore,serve as a biological control agent in integrated pest management?IPM?.