A Fixed-Precision Sequential Sampling Plan for the Potato Tuberworm Moth, <Emphasis Type="Italic">Phthorimaea operculella</Emphasis> Zeller (Lepidoptera: Gelechidae), on Potato Cultivars

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.     

Chromosome aberrations in peripheral blood lymphocytes of individuals living in high background radiation areas of Ramsar,Iran

In order to investigate the biological effects of exposure to low-dose radiation and to assess the dose–effect relationship in residents of high background radiation areas (HBRAs) of Ramsar, cytogenetic investigation of unstable-type aberrations was performed in 15 healthy elderly women in a HBRA of Ramsar, Talesh mahalle, and in 10 elderly women living in a nearby control area with normal background radiation. In total, 77,714 cells were analyzed; 48,819 cells in HBRA residents and 28,895 cells in controls. On average, 3,108 cells per subject were analyzed (range 1,475–5,007 cells). Significant differences were found in the frequency of dicentric plus centric rings in 100 cells (0.207 ± 0.103 vs. 0.047 ± 0.027, p < 0.0005), total chromosome-type aberrations per 100 cells (0.86 ± 0.44 vs. 0.23 ± 0.17, p < 0.0005), and chromatid-type aberrations per 100 cells (3.31 ± 2.01 vs. 1.66 ± 0.63, p = 0.01) by the Mann–Whitney U test between HBRA and the control, respectively. Using chromosomal aberrations as the main endpoint to assess the dose–effect relationship in residents of HBRAs in Ramsar, no positive correlation was found between the frequency of dicentric plus centric ring aberrations and the cumulative dose of the inhabitants estimated by direct individual dosimetry; however, obvious trends of increase with age appeared in the control group. Based on these results, individuals residing in HBRAs of Ramsar have an increased frequency of detectable abnormalities in unstable aberrations.     

Cytogenetic effects of radiation and genetic polymorphisms of the XRCC1 and XRCC3 repair genes in industrial radiographers

Radiation and Environmental Biophysics - Different types of DNA damages caused by ionizing radiation may enhance the cancer risk in exposed individuals. Inherited variations in DNA repair genes...     

Chemical compositions of leaf extracts from Conocarpus erectus L. (Combretaceae) and their bioactivities against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae)

Botanical insecticides have long been considered as alternatives to synthetic chemical insecticides in IPM programs. Effects of aqueous and ethanolic extracts obtained from buttonwood, Conocarpus erectus L. (Combretaceae), leaves on a major kind of stored product pests, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), were evaluated under laboratory conditions. For this purpose, LC₅₀, repellency, antifeedant properties, and some biological effects (including body weight, immature developmental time and survival) of the insect were determined. The aqueous and ethanolic extracts were highly toxic to the larvae and adults. Calculated LC₅₀ values ranged between 2.6 and 193.4 (g/kg). Both extracts had repellent and antifeedant properties against the adults. The extracts adversely affected the larval and pupal weights, developmental time, and survival. Aqueous extracts were more effective only for the LC₅₀ values and only in females. All other measured parameters do not differ between the two extracts. The bioactive properties might be related to high amounts of alkaloid, phenol and tannin. Aqueous extract of the plant leaves may be a useful alternative for chemical insecticides.