Spatial Distribution and Minimum Sample Size for Overwintering Larvae of the Rice Stem Borer Chilo suppressalis (Walker) in Paddy Fields

Abstract

The rice stem borer, Chilo suppressalis (Walker), feeds almost exclusively in paddy fields in most regions of the world. The study of its spatial distribution is fundamental for designing correct control strategies, improving sampling procedures, and adopting precise agricultural techniques. Field experiments were conducted during 2011 and 2012 to estimate the spatial distribution pattern of the overwintering larvae. Data were analyzed using five distribution indices and two regression models (Taylor and Iwao). All of the indices and Taylor's model indicated random spatial distribution pattern of the rice stem borer overwintering larvae. Iwao's patchiness regression was inappropriate for our data as shown by the non-homogeneity of variance, whereas Taylor's power law fitted the data well. The coefficients of Taylor's power law for a combined 2 years of data were a = -0.1118, b = 0.9202 ± 0.02, and r (2) = 96.81. Taylor's power law parameters were used to compute minimum sample size needed to estimate populations at three fixed precision levels, 5, 10, and 25% at 0.05 probabilities. Results based on this equation parameters suggesting that minimum sample sizes needed for a precision level of 0.25 were 74 and 20 rice stubble for rice stem borer larvae when the average larvae is near 0.10 and 0.20 larvae per rice stubble, respectively.

Consequences of diapause on post‐diapause development, reproductive physiology and population growth of Chilo partellus (Swinhoe)

“…A diapause strategy helps insects to adapt to changing environments and enhance their survival capacity (Neal et al, 1997;Lehmann et al, 2015), although there can be a cost to diapause (Jiang et al, 2010;Arbab, 2014). Diapause costs could be determined in the form of a decrease in adult body weight, fecundity, longevity, reproductive performance and reproductive investment by adults (Irwin & Lee, 2000;Win et al, 2013;Win & Ishikawa, 2015).…”

Effects of seed mixture sowing with transgenic Bt rice and its parental line on the population dynamics of target stemborers and leafrollers, and non‐target planthoppers

“…7B and D), and there Fig. 6 The rate of dead heart and white head tillers caused by rice stemborers, Sesamia inferens (A-2013; C-2014) and Chilo suppressalis (B-2013; D-2014), in the paddyfields under six ratios of seed mixture treatments with transgenic Bt rice and its non-transgenic parental line from July 29 to September 30, 2013 and2014. was no significant difference between Bt 100 and Nt 05 Bt 95 (2013: 2096.6 g; 2014: 2175.5 g) (P > 0.05; Fig. 7B and D).…”

Random or clumped: How litter dwelling scorpions are distributed in a fragment of Brazilian Atlantic forest

“…How individuals in a population are distributed in their respective habitats (i.e., species distribution) can be determined either at the species-level (e.g., among different species) or at the population level (e.g., among populations of the same species) (Rodrigues et al, 2010;Arbab et al, 2014;Sujithra & Chander, 2016). Within a habitat, availability of resources (e.g., shelter, food) and environmental factors (e.g., dry and rainy periods) are likely to infl uence the distributions of species (Eterovick & Barata, 2006;Leal et al, 2016;Lira et al, 2018a).…”