Pyemotes sp.and Scleroderma guani were used to control the larvae of Semanotus bifasciatus.The results as follows:(1) the suitable control time of Pyemotes sp.was from early April to early May.The reason was that in this time,the larvae of S.bifasciatus were young and not bored into xylem that was so easy to be parasitized by Pyemotes sp.With the parasitic rate 80% in average.Indoor experiment showed that the Pyemotes sp.had the same tropism selection to every instar for the host,but the parasitic rate was higher in low instar than other instars.(2)Using Scleroderma guani to control S.bjfasciatus,the suitable time was from mid May to mid June,the optimal ratio of host and parasite was 1∶1.Indoor experiment showed that Scleroderma guani had strong tropism toward middle-aged and elder larvae,the parasite linger around them and choose suitable position on hosts where they could lay eggs successfully.This behavior showed that Scleroderma guani had strict selectivity for their hosts.In experiment,the authors found a phenomenon that in one trap wood,both the Pyemotes sp.and Scleroderma guani could be found at the same time,they themselves did not affect each other and otherwise they could increase the parasitic rate for host.So,the authors suggested that in practice to control pests especially for boring pests,the Scleroderma guani and Pyemotes sp could be used at the same time.
The Asian longhorned beetle Anoplophora glabripennis is a wood-boring beetle that,upon severe outbreaks,causes great damage in the artificial shelter-forest of the Three-Northern Areas.The great spotted woodpecker Picoides major is one of the natural predators of A.glabripennis.P.major is also a common species in Wulate Qianqi of the Inner Mongolia Autonomous Region and is widely distributed in the artificial shelter-forest.The wood-boring beetle is an important food source of P.major,especially during the winter.Despite the potential of P.major to control A.glabripennis populations,surprisingly little is known about their predator-prey interactions.This information is essential to predicting the efficacy of P.major as a control agent to A.glabripennis.Therefore,it is important to study how the predator responds to changes in prey density.From 2006 to 2008,fifteen study plots were selected,and the predation of P.major on A.glabripennis was examined with sample plot and trace investigation,the latter being in the field.The results showed that the function response of P.major to A.glabripennis was Holling Ⅲ,with a non-linear regression equation.The increase in predation capacity correlated with the increase in A.glabripennis density,within a certain density range.As the density of A.glabripennis increased,the predatory capability had a positive acceleration phase,then a negative acceleration phase,and finally a saturation state.Likewise,as the density of A.glabripennis increased,the predation rate initially increased,peaked,and was reduced in the end,with a non-linear regression equation.The results indicated that the numerical response was a positive reaction to density.In other words,the population density of P.major increased as the density of A.glabripennis increased.
