A Fixed-Precision Sequential Sampling Plan for the Potato Tuberworm Moth, Phthorimaea operculella Zeller (Lepidoptera: Gelechidae), on Potato Cultivars

Abstract

Phthorimaea operculella Zeller is an important pest of potato in Iran. Spatial distribution and fixed-precision sequential sampling for population estimation of the pest on two potato cultivars, Arinda and Sante, were studied in two separate potato fields during two growing seasons (2013-2014 and 2014-2015). Spatial distribution was investigated by Taylor's power law and Iwao's patchiness. Results showed that the spatial distribution of eggs and larvae was random. In contrast to Iwao's patchiness, Taylor's power law provided a highly significant relationship between variance and mean density. Therefore, fixed-precision sequential sampling plan was developed by Green's model at two precision levels of 0.25 and 0.1. The optimum sample size on Arinda and Sante cultivars at precision level of 0.25 ranged from 151 to 813 and 149 to 802 leaves, respectively. At 0.1 precision level, the sample sizes varied from 5083 to 1054 and 5100 to 1050 leaves for Arinda and Sante cultivars, respectively. Therefore, the optimum sample sizes for the cultivars, with different resistance levels, were not significantly different. According to the calculated stop lines, the sampling must be continued until cumulative number of eggs + larvae reached to 15-16 or 96-101 individuals at precision levels of 0.25 or 0.1, respectively. The performance of the sampling plan was validated by resampling analysis using resampling for validation of sampling plans software. The sampling plant provided in this study can be used to obtain a rapid estimate of the pest density with minimal effort.

Spatial Distribution Pattern and Sampling Plans for Two Sympatric Tomicus Species Infesting Pinus yunnanensis during the Shoot-Feeding Phase

“…Therefore, there is an opportunity to test field experiments using the push–pull strategy based on aggregation and anti-aggregation pheromones of Tomicus to develop potential IPM techniques. The present results were not consistent with those from other insects; for example, Shahbi and Rajabpour [ 44 ] showed that the spatial distribution of Phthorimea operculella Zeller (Lepidoptera: Gelechidae) tended toward randomness with low egg and larval densities.…”

Effect of weedy culture on population densities, spatial distributions and sampling procedures ofSpodoptera exiguaandSesamia cretica(Lep., Noctuidae) in corn fields

“…The regression slope ‘ b ’ is an index of species spatial pattern. When b < 1, b = 1, and b > 1, the spatial distribution pattern of the larvae is uniform, random, and aggregated, respectively (Southwood, 1978; Shahbi & Rajabpour, 2017; Kafeshani et al ., 2018). Also, the regression coefficient ( r 2 ) was calculated to obtain goodness of fit of TPL.…”

“…The sequential sampling plan was validated by Resampling for Validation of Sampling Plans (RVSP) software based on Naranjo & Hutchison's (1997) method. The software requires independent data sets to serve as validation data sets (Shhabi & Rajabpour, 2017; Kafeshani et al ., 2018). Hence, ten independent data sets with a range of low-, medium-, and high-density levels of each pest larvae were randomly selected from a total of 38 data sets, which were collected from two growing seasons in the non-weedy and weedy corn cultures.…”

“…Information about biological aspects of pests, e.g., seasonal population dynamics and spatial distribution, is critical for developing integrated pest management (IPM) program (Pedigo, 2002; Rajabpour & Yarahmadi, 2012; Yarahmadi & Rajabpour, 2013). Appropriate sampling plan, i.e., easy to implement and suitable for the rapid decision-making process, is needed to establish successful IPM program (Namvar et al ., 2012; Shahbi & Rajabpour, 2017; Kafeshani et al ., 2018). In comparison with conventional sampling plan, where a fixed number of samples are used for population estimation, sequential sampling plan can result in a 35–50% reduction in sampling effort (Binns, 1994).…”

Morphological and molecular identification of four isolates of the entomopathogenic fungal genus Akanthomyces and their effects against Bemisia tabaci on cucumber

“…The application of synthetic insecticides such as imidacloprid is the main strategy to control B. tabaci in many regions of the world (Palumbo et al ., 2001). Pesticide resistance, side effects on non-target organisms, pest resurgence, and secondary pest outbreak are some limitations of the chemical control (Pedigo, 2002; Safaei et al ., 2016; Shahbi and Rajabpour, 2017).…”