Department of Statistics and Mathematics, Acharya NG Ranga Agricultural University, Rajendranagar, Hyderabad - 500 030, Andhra Pradesh, India. E mail: akjangam@yahoo.com
The distribution pattern of rice brown planthopper (BPH), Nilaparvata lugens Stal. was studied by taking the data of on farm trials. Observations on variance and mean revealed that the pest followed the negative binomial distribution. The dispersion parameter ‘K’ calculated by the proportion of zeros and also by the trial and error method conclusively proved that the distribution of rice BPH was aggregated in nature. A similar type of distribution was observed by computing the data for the tests like ÷2, U and T statistics. The various indices of dispersion used in the study such as Cole's index, David and Moore's index and Morisita's index further confirmed the contagious distribution of the rice BPH.
Ecological studies, distribution pattern, rice pests, brown planthopper, indices of dispersion, negative binomial distribution
