Spatial dispersion and sequential sampling plan for black bean aphid, Aphis fabae Scopoli, on faba bean fields in Veis region, Ahvaz

Black bean aphid، Aphis fabae Scopoli، is the most important pest of faba bean that causes economic damage on this crop. Spatial dispersion of the aphid using Taylor power law and Iwao patchiness indices was studied by weekly sampling in faba bean fields of Veis region، Ahwaz، during 2010-2012. Taylor''s power law and Iwao patchiness were used to investigate spatial dispersion of A. fabae and a resampling for validation of sampling technique (RVSP) was used to develop a Green''s fixed precision sequential sampling for this aphid population at precision levels of 0. 25 and 0. 1. Results showed that A. fabae had aggregation dispersion on faba bean and Taylor''s power law had more fitness to the obtained data. The Optimum sample size to estimate the population density of A. fabae ranged from 25 to 2 and 73 to 10 samples depending on population densities at precision levels of 0. 25 and 0. 1، respectively.