Spatial distributions and sampling of cotton arthropods with special reference to sequential sampling
Loading...
Files
Date
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Discrete frequency distributions obtained from samples of various arthropods commonly found in Texas cotton fields were fitted to 6 discrete mathematical frequency distribution models. The observed frequency distributions most frequently fit the negative binomial expectations which suggests a clumped pattern of dispersion. These same arthropods were seldom observed to be randomly dispersed as indicated by poor agreement with the Poisson expectations. Two indices were used to quantify the aggregation of cotton arthropods: the parameter K of the negative binomial distribution and Morisita's index of dispersion I[subscript delta]. Using frequency distribution data the average value of these indices were calculated. In general there was a close agreement between K and I[subscript delta]. Cotton fleahopper, Pseudatomoscelis seriatus (Reuter), nymphs were more aggregated than fleahopper adults. A greater degree of aggregation was observed for boll weevil, Anthonomus orandis Boheman, eggs than for boll weevil adults. Bollworm, Heliothis zea (Boddie) and tobacco budworm H. virescens (Fabricius), eggs exhibited more aggregation than Heliothis spp. larvae. Aggregation continued to decrease as the Heliothis spp. larvae became full grown. Among the predatory arthropods, lady bettles and minute-flower bugs, Orius spp. displayed the greatest amount of aggregation. Big-eyed bugs, Geocoris spp. were less aggregated and the spatial distributions of spiders were the least aggregated of the predatory arthropods. ...
Description
Keywords
entomology