Evaluation Of Predation Potential Of Neoseiulus Striatus On Two Species Of Tetranychus Mites

Tetranychus urticae and Tetranychus truncatus were known as worldwide important spider mites in agricultural and forestry crops.It is difficult to control Tetranychus mites because it has developed resistance to a variety of pesticides.Biological control of spider mites by predatory mites is widely used as an important method to reduce the application of chemical pesticides.In this thesis,under the laboratory conditions(25±1°C,65±10%RH and 16L:8D photoperiod)with the phytoseiid mite,Neoseiulus striatus,which was recently found on corn plants in Inner Mongolia,the functional response of N.striatus to all stage in different densities of T.urticae was studied,and the experiment population life table of N.striatus on the natural prey or alternative prey was established.Meanwhile,the predation potential of N.striatus to Frankliniella occidentalis and Bemisia tabaci was preliminarily evaluated as well.This study not only provides a reference for the control of spider mites and small sucking pests,but also provides theoretical support for the mass rearing of N.striatus in the laboratory.The major result were as follows:1.Functional responses of N.striatus to each developmental stage in different densities of T.urticaeThe functional responses of N.striatus to each developmental stage in different densities of T.urticae was in accordance with Holling II equation.The attack rate(a)to eggs,larvae,protonymphs,deutonymphs and adults of T.urticae was 1.8564,3.4499,1.2023,1.6348,0.8374,respectively.The treatment time(Th)to different developmental stages of T.urticae was 0.0081,0.0109,0.0085,0.0380,0.0396,respectively.The theoretical maximum daily predation to different stages of T.urticae were 123.3046,91.7431,118.0638,26.3158,25.2523,respectively.Therefore,N.striatus has a high predation ability for T.urticae.2.Experimental population life tables of N.striatus on the natural prey of T.urticae and T.truncatus.N.striatus could complete its whole life cycle by fed on T.urticae and T.truncatus.The generation duration were 7.61±0.18 d and 7.25±0.12 d,respectively.The number of female progeny of N.striatus fed on T.urticae were higher(49.17±1.88 eggs)than that fed on T.truncatus.Meanwhile,when fed on T.truncatus and T.urticae,N.striatus showed higher r_mvalues which was 0.1850 and 0.1880,respectively,indicating that both of two species of spider mites were beneficial to development and fecundity of N.striatus.The reproductive mode of N.striatus was parthenogenesis under the condition of 25±1°C,65±10%RH and 16L:8D photoperiod.3.Fecundity life table of N.striatus on two kinds of alternative prey of C.lactis and T.latifolia pollen.N.striatus could complete its generation by feeding on C.lactis and T.latifolia pollen.When fed on T.latifolia pollen,the generation duration(6.38±0.15 d)of N.striatus was shorter than that fed on C.lactis,but the oviposition period and the life span of N.striatus were longer than that fed on C.lactis,which were 22.40±1.03 d and24.63±1.04 d,respectively.However,when fed on C.lactis,the total fecundity(29.00eggs)of N.striatus was higher than that fed on T.latifolia.The results showed that N.striatus had a faster development rate and a longer life span when fed on T.latifolia,while its fecundity was higher when was fed on C.lactis.4.Preliminary evaluation on predatory potential of N.striatus to other small sucking pests.The average daily predation of N.striatus on 1st instar of F.occidentalis was 4.24,while it was 8.83 on 1st instar of B.tabaci.The results indicated that N.striatus had certain control potential of F.occidentalis and B.tabaci.