Abstract
Recently, the Neotropical brown stink bug, Euschistus heros (Pentatomidae: Hemiptera), has been detected in cotton in the Brazilian Cerrado. Several reliable surveys have been conducted on the spatial distribution of stink bugs in soybean; however, few studies have examined the behavior of this insect in cotton in Brazil. Thus, this study examined the spatial distribution of E. heros in cotton using aggregation indices based on the variance-to-mean ratio, Morisita index, exponent k, Poisson and negative binomial distributions. Inverse Distance Weighting interpolation maps were also used to represent insect density. The study was conducted in a 1.1 hectare experimental cotton field in which 64 equally-sized plots were sampled on a weekly basis. Our findings revealed that stink bugs presented an aggregate distribution in 2 sampling weeks based on aggregation indices, and this pattern was best described by a negative binomial distribution. Maps showing the density of pests can be an important tool for sampling pests in crops and control measures in early stages of infestation, when there is an edge effect on the distribution of E. heros, can be an efficient strategy in cotton.
Highlights
The Neotropical brown stink bug, Euschistus heros (Hemiptera: Pentatomidae) (F.), usually occurs in the cotton and is becoming an economically important pest for Brazilian cotton growers (Soria et al 2009)
In the first and second sampling dates, insects were found in the plots on the edge of the cotton field (Fig. 2), indicating the arrival of the pest from adjacent areas planted with corn
The results suggest that E. heros adults were aggregated in the cotton field, and is best described by the negative binomial distribution, since variance values were higher than the mean, besides the negative binomial values were lower than those obtained for the Poisson distribution, approaching zero
Summary
The Neotropical brown stink bug, Euschistus heros (Hemiptera: Pentatomidae) (F.), usually occurs in the cotton and is becoming an economically important pest for Brazilian cotton growers (Soria et al 2009). The high incidence of E. heros is caused by the simultaneous sowing of soybean and cotton, in which stink bugs migrate from the former to the latter. This occurs due to an inefficient pest control in soybean, high density of insects, and dispersion of the pest population from one area to another in search of food, and the attacks coincide with the formation of bolls, the most critical stage in the development of cotton (Soria et al 2010, 2009). Spatial distribution models can identify when a species has a regular, random, or aggregated spatial distribution in field, in which probabilistic models of Poisson, positive and negative binomial distributions are respectively used to describe the types of pattern of a pest (Young and Young 1998)
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