Spatial distribution pattern and sampling technique of the larvae of European sunflower moth, Homoeosoma nebulellum

Abstract：  The European sunflower moth, Homoeosoma nebulellum Denis et Schiffermüller is a serious pest of sunflower crops. Six aggregation indexes were used to identify the spatial distribution pattern of H. nebulellum larvae. The results show that this pest has an aggregated distribution pattern. The formula of the logarithm of the mean (m) and variance (S2) was:lgS2=lg0.2130+0.5639lgm, which meant that the distribution pattern of the larvae became progressively more even with increasing density. According to Iwao’s regression:m*=8.1177+0.1447m, the basic element of distribution was an individual colony in the field, individuals attract each other and individual colonies are evenly distribution. The aggregation mean λ (λ<2) indicated that the cause for the aggregated distribution was the environment. A theoretical sampling formula for the larvae of H. nebulellum was established as followed. n=911.77/m-85.53 (D=0.1) and n=227.94/m-21.38 (D=0.2). The sequential sampling formula were T1(n),T0(n)=7.40n±4.54 n (Confection sunflower) and  T1(n),T0(n)=10.05n±2.29 n (Oil sunflower).
Key words   sunflower, sunflower moth, Homoeosoma nebulellum, Homoeosoma electellum, spatial distribution pattern, sampling technique