Temporal variation and spatial distribution of the pest insect Edessa meditabunda in cotton (Gossypium hirsutum) as an alternative host plant

Abstract

Cotton is an alternative host for Edessa meditabunda (Hemiptera: Pentatomidae), especially after the soybean harvest in surrounding areas, when large numbers of insects invade cotton fields and damage reproductive structures such as flowers and developing bolls. However, no studies on its occurrence and spatial distribution have been conducted in cotton. Therefore, this study was aimed to assess the temporal variation and spatial distribution of E. meditabunda in the alternative host plant, Gossypium hirsutum. The study was carried out in an area of 1.1 ha planted with cotton that was divided in 64 plots of 169 m 2 each, where entire cotton plants were examined weekly and E. meditabunda nymphs and adults were counted. Dispersion rates and theoretical frequency distributions were calculated and analyzed with significance level at 5%. Assessments were carried out from seedling emergence until the appearance of bolls, but E. meditabunda was present only during the reproductive stage of cotton plants. This study detected the dispersal of this stink bug from late-cycle soybean fields to cotton, indicating cotton's potential as an alternative host plant, providing shelter and food. Based on aggregation indices, the spatial distribution of nymphs and adults in cotton was aggregated at the beginning of the infestation, but tended toward randomness as bolls reached maturity. The occurrence of E. meditabunda in cotton was best described by the Poisson distribution with significance level at 5%.

Temporal variation and spatial distribution of Euschistus heros (Hemiptera: Pentatomidae) during the soybean grain formation period

“…The result obtained for the movement of nymphs in this study corroborates with that obtained by Weber et al (2018) when studying the distribution of E. heros nymphs in cotton, and Silva et al (2021), when studying the distribution of E. meditabunda nymphs in cotton, who observed a trend of infestation by the borders and randomness at the beginning of the infestation. However, the nymphs moved to the center of the experimental area in the following evaluations and remained aggregated.…”

“…However, only the distribution pattern of insects (random, aggregate, or uniform) is taken into account when only dispersion and frequency distribution indices are used, not considering the location of the insect in the field, which is obtained by spatial analysis (Silva et al, 2021).…”

“…Furthermore, the use of geostatistics can be a complementary tool to graphically visualize how these insects are distributed in the field, providing useful visual information about the shape and location of the spatial distribution of pests under field conditions (Sciarretta & Trematerra, 2014). Therefore, knowledge of spatial distribution can be an important tool when associated with the integrated pest management to be considered when choosing to carry out chemical control of this insect, aiming at higher efficiency and reduction of control costs and damage to the environment (Pereira et al, 2018, Silva et al, 2021. In addition, little information can be found in the literature on the spatial distribution of E. heros during the soybean grain formation period.…”

Journal of Plant Protection Research

“…The indiscriminate use of pesticides can also cause ecological and economic problems. Therefore, measures aimed at providing guidelines for the use of insecticides are essential (Silva et al 2021).…”

“…Based on these results, the species distribution can be described as aggregate, random and uniform. However, for confirmation of this distribution it is necessary to know how to adjust theoretical frequency for each species and for each specific crop (Silva et al 2021).…”