Group function of different predators and parasitoids combinations against Bemisia tabaci.pdf

1、Bemisia tabaci(Gennadius)(Homoptera，Aleyrodidae)biotype B is an economicalpolyphagous insect pest of different agricultural crops in Pakistan as well as China．In thepresent research work，life table parameters of B．tabaci

2、 on tomato and cotton host plantswere determined．Life table parameters and predatory efficiency of Coccinellaseptumpunctata，Harmonia axyridis,Propylaeajaponica(Coleoptera，Coccinellidae)and Chrysopa pallens(Neuroptera。Chr

3、ysopidae) with un-parasitized and E．formosaparasitized B．tabaci biotype B prey was recorded．Life table parameters andparasitization efficiency of Encarsiaformosa(Homoptera，Aphelinidae)was determined with B．tabaci biotype

4、 B prey．A series of experiments were conducted to find intra-andnterguild predation among the different predators．All the experiments were conducted incl imatic chambers set at a temperature of 25±2℃，relative humidity of

5、 60±5％，photoperiod of 16:8h(L:D)and an artificial light intensity of about 4000 lux on fleshtomato leaves as arena of observation．The results of experiments with B．tabaci showedthat it had longer embryonic well as immatu

6、re developmental duration and longevityOn cotton than on tomato host．Also，fecundity WaS higher On cotton than on tomato．But，mortal ity was lower on cotton than on tomato．The female：male adults sex ratio was52:48 on tomat

7、o，while 55:45 on cotton．Comparison of the life table of C.septempunctata and H．a(chǎn)xyridis revealed that mean total duration from egg to adult stagewas 26.5 and 24.8 days for C．septempunctata and 20.6 and 19.9 days for H．a(chǎn)x

8、yridisfemales and males，respectively．Mean adult longevity of C. septempunctata WaS 74.8and 61.8 days and of H．a(chǎn)xyridis 62.6 and 47.3 days for females and males，respectively.C. septempunctata laid a mean total number of 7

9、10.5 eggs/female，while H. axyridis542.0 eggs/female．Total mortality during different immature stages of C．septempunctatawas 35.8％ and of H. aryridis it WaS 37.2％．Female to male sex ratio was 51:49 for C.septempunctata an

10、d 52:48 for H. axyridis．Prey consumption experiments by C.septempunctata and H. axyridis showed no difference in the number of un-parasitized orE. formosa parasitized B．tabaci eggs and N1 consumed by the immature and adu

11、ltpredator stages．C．septempunctata and H．a(chǎn)xyridis larvae as well as adults consumedsignificantly higher number of un-parasitized N2，N3，N4 and pupal prey than the E.．formosa parasitized these prey stages．The number of all

12、 prey stages consumed，both un-parasitized as well as E. formosa parasitized，increased in the subsequent larval stages ofthe predators．The adult females consumed higher number of all prey stages，both un-parasitized as wel

13、l as E.formosa parasitized,than the males．Encarsia formosa parasitized and completed development in N2，N3，N4 instars and pupal stage of B．tabaci，where development was significantly faster in N4 and pupal stages than in N

14、2，N3，instarsof the prey，Mean duration of development was 22.0，19.1，16.1 and 14.3 days when N2，N3，N4 instars and pupal stage of B．tabaci were parasitized，respectively．There was nodifference in longevity of the parasitoid

15、emerging from the different instars of the prey，where it was 12.5，12.2，12.4 and 12.4 days in N2，N3，N4 instars and pupal stage of B.tabaci，respectively．But，total duration of the parasitoid life cycle Was longest in N2，ins

16、tar(34.6 days)and shortest in pupal stages(26.7 days) of the prey．The total numbersofeggs laid by the parasitoid female during the first 12 days of longevity were 81.7，84.2，76.8 and 74.8 eggs/female in the N2，N3，N4 insta

17、rs and pupal stage of B．tabaci，respectively．During the first 12 days of longevity，the wasp consumed/killed highermean total number of N2(36.9)，N3(35.7)and N4(34.6)instar individuals than N1 instar(18.8)or pupa(25.9)of B．

18、tabaci．Host age had an effect on percent adult emergence of E. formosa，which ranged between 85％ (N2) and 96％ (N4)．The results of life tableexperiment of C. pallens showed that recall duration of embryonic，L1，L2，L3 and pu

19、pawere 7.0 ,4.2, 6.2, 8.2 and 12.2 days，respectively．Mean longevity of C．septempunctatawas 56.8 days for females and 46.4 days for males．Mortality occurred during all thedevelopmental stages of the predator where total m

20、ortality from egg-pupal stage was35.8％．C. pallens laid a mean total number of 397.4 eggs/female．C. pallens consumedhigher number of un-parasitized N2，N3，N4 and pupal prey than the E．formosaparasitized these prey stages，w

21、here the consumed number of all prey stages increased inthe subsequent larval stages of the predator．The results of experiment with P．japonicashowed that the predator Was able to develop and reach the adult stage with B．

22、tabaci asprey．Mean developmental duration of egg，LI，L2，L3，L4 and pupal stage was 3.6, 2.1,，3.0, 3.2, 3.4, 3.3 days for females and 3.4, 2.2, 2.9, 3.0, 3.4, 3.1 days for males，respectively．Mean total duration from egg to

23、adult was 18.8 days for females and 18.0 days for males．The prey consumption experiments showed that the immature as well asadu lt predator consumed almost similar number of un-parasitized B．tabaci eggs as weltas N1 and

24、 E．formosa parasitized these prey stages．P．japonica consumed higher numberof un-parasitized N2，N3，N4 and pupal prey than the E. formosa parasitized these preystages．The consumed number of all prey stages increased in the

25、 subsequent immaturestages of the predator，where the adult females consumed higher number of all preystages than the males.The intraguild predation experiments showed that all of thepredators consumed/killed their embryo