Spatial distribution pattern and sampling technique for larvae and galls of Procecidochares utilis Stone

ObjectiveThe paper clarified the distribution characteristics of the larvae and galls of Procecidochares utilis Stone in the field to provide theoretical guidance of applying P. utilis on the biological control of Eupatorium ade-nophorum Spreng and improve its prevention effects.MethodChessboard sampling methods was used to investigate the distribution of larvae and galls in three selected plots near Songhua Village,Chenggong District,Kunming City,Yunnan Province where the invasion of E. adenophorum was very serious. The spatial distribution pattern of P. utilis larvae and galls in the field was analyzed by six aggregation indices(diffusion coefficient,clumping index,aggregation index,index of patchiness,La index and parameter of negative binominal)and two regression models(Iwao regression equation and Taylor power law),while aggregation mean was used to test and determine the reasons for the aggregation of those larvae and galls. Finally,according to Iwao theoretical sampling formula and sequential sampling theory formula,the theoretical sampling model and sequential sampling model were established.ResultThe results showed that the spatial distribution pattern of those larvae and galls belonged to the aggregation distribution,and their basic components were individual groups. In larvae population,individuals attracted each other,but among the galls,the individuals excluded. Aggregation mean analysis suggested that the gather reason of those larvae and galls was caused jointly by its oviposition,feeding habits and the environment. The theoretical sampling models of P. utilis larvae and galls were set up:N=(9.919/m+1.033)/D2, N=(6.632/m+0.015)/D2. Their sequential sampling models were as follows:T0=10n ± 1.9617.24n+0.4 ,T0=10n ± 1.966.77n+4 .ConclusionThe spatial patterns of P. utilis larvae and galls are aggregation distribution in the field. The aggregation of larvae and galls is mainly caused by its oviposition,feeding habits and the environment.