Examining the spatial distribution pattern of corn planthopper, Peregrinus maidis in corn - sunn hemp intercropping system and corn monoculture

Sampling procedures designed for scouting pests often assume that the population is distributed randomly across the field. However, there is growing evidence that suggests this assumption is unjustified and may affect pest management practices used, based on sampling results. Here, we study spatial distribution pattern of corn planthopper, Peregrinus maidis in corn – sunn hemp intercropping system and compared with corn monoculture. We assume that corn grown inbetween rows of sunn hemp will alter the dispersion pattern of P. maidis, resulting in lower populations within the field. Adults of macropterous P. maidis were counted in corn whorls on spatially referenced corn plants at weekly intervals. Count data were spatially analyzed to compute distance indices using Spatial Analysis for Distance IndicEs (SADIE) software. The following parameters: distance to regularity (D), aggregation index (I_a), and clustering index (n) were compared between the cropping systems using ANOVA. Results showed the population distribution of P. maidis often found to be aggregated with conspicuous patches and gaps. Intercropping corn inbetween the sunn hemp rows did not reduce the dispersal of P. maidis. In conclusion, the dispersing P. maidis were rarely randomly distributed and sunn hemp did not help in minimizing P. maidis populations within the field. This study suggests a new approach for sampling P. maidis, which can be used for identification of hot spots for appropriate use of pest management practices.