Intraguild Predation Among Three Species Of Indigenous Phytoseiid Mites

Amblyseius andersoni,Neoseiulus barkeri and Neoseiulus sp.were newly found from same habitat in Bayan Nur city,Inner Mongolia.In this thesis,from the viewpoint of behavioral ecology,the potential occurrence of intraguild predation（IGP）between A.andersoni and N.barkeri,N.barkeri and Neoseiulus sp.were studied respectively under different shared resources,including Tetranychus truncatus or Tetranychus urticae juveniles,1^st larvae of Frankliniella occidentalis,and pollen（Typha sp.）.The results will helpful to understand trophic relationship among three phytoseiid mites and provide the basis for the protection and rational management of native phytoseiid mites.The main results were as follows:1.Evaluate the potential occurrence of intraguild predation between Amblyseius andersoni and Neoseiulus barkeriThe occurrence of IGP between A.andersoni and N.barkeri was investigated with pollen and T.truncatus as the shared resource,respectively.The results supposed that the IGP between A.andersoni and N.barkeri occurred in the presence of the T.truncatus with A.andersoni as IG-predator and N.barkeri as IG-prey,but didn’t occur with pollen as shared resource.Meanwhile,predation selectivity of A.andersoni and N.barkeri on the heterospecific juvenile mites and the shared resource（T.truncatus）was studied,and the results proved that the female A.andersoni preferred N.barkeri juveniles to T.truncatus,while the female N.barkeri favoured T.truncatus than A.andersoni juveniles.2.Ontogenetic stage-specific intraguild predation between Neoseiulus barkeri and Neoseiulus sp.The predatory interactions of all feeding stages of N.barkeri and Neoseiulus sp.was evaluated to explore whether IGP occurred in different ontogenetic stage.Except that female N.barkeri didn’t prey on female Neoseiulus sp.,the female adults of both species could prey on heteospecific species in the same and lower stages,and exhibited same aggressiveness between two species.Meanwhile,nymph of both species could feed on smaller stages of the other species.Both species of phytoseiid mites were able to complete their growth and development when they preyed on heterospecific egg,larvae or nymph.The development duration was the shortest when they fed on heterospecific larvae,which indicating that heterospecific larvae was more suitable for the individual growth of N.barkeri and Neoseiulus sp.3.Evaluate the potential occurrence of intraguild predation between Neoseiulus barkeri and Neoseiulus sp.with different types of shared resourcesThe potential occurrence of IGP between N.barkeri and Neoseiulus sp.was estimated under different shared resources with the larvae of each species as IG-prey.The results proved that IGP occurred in the presence of T.urticae when Neoseiulus sp.as IG-predator and N.barkeri as IG-prey;but when the shared resource was F.occidentalis,IGP didn’t occur between two species of phytoseiid mites.4.The effect of IG-prey and shared resources on the predation of Neoseiulus barkeri and Neoseiulus sp.The effects of heterospecific larvae and shared resources on fitness and preference of N.barkeri and Neoseiulus sp.with T.urticae and F.occidentalis as shared resources were studied,respectively.The results showed that N.barkeri was preferred T.urticae to heterospecific larvae,and the development time of N.barkeri was the shortest when fed on T.urticae.Meanwhile,Neoseiulus sp.preferred heterospecific larvae,and the development time of Neoseiulus sp.was the shortest when fed on F occidentalis.Thus,T.urticae was more suitable for the individual growth of N.barkeri,but F occidentalis was still more suitable for the individual growth of Neoseiulus sp.than heterospecific larvae.