Applied Entomology and Phytopathology
Year:2016 | Volume:83 | Issue:2|Papers Count:6

Study on the genetic structure ofFusarium verticillioides populations, provides different levels of information in management of root rot disease in rice farms. Simple Sequence repeat (SSR) markers were used to determine genetic structure and genetic diversity in 39F.verticillioidesisolates from five different regions in Ilam province, such as: Tangehghir, Lomar, Shirvan, Sarableh and Darehshahr. Average number of alleles in populations were 10.6, the number of alleles in populations varied from 9 allele in Tangehghir and Darehshahr as the lowest to 13 allels in Lomar as the highest. Observed number of alleles (Na) and effective number of alleles (Ne) were higher in Lomar (Na= 1; Ne=1.276) compared to other populations. The genetic diversity (H) and Shannon's Information index (I) were also higher in Lomar (H= 0.167; I=0.254) but lower values were estimated for Darehshahr (He=0.141; I=0.204). The lowest genetic distance was found between Tangehghir and Lowmar (0.00) and then Shirvan, while the highest genetic distance was revealed between Darehshahr and Tangehghir (0.018). Total gene diversity (Ht) and gene diversities between subpopulations (Hs) were estimated 0.125 and 0.116, respectively. Gene diversity attributable to differentiation among populations (Gst) was 0.072, while gene flow (Nm) was 6.368. Cluster analysis based on UPGMA showed the lowest genetic distance between Tangehghir and Lomar and then between Shirvan. The dendrogram indicated a high genetic distance between Darehshahr and four remaining populations. Results from this study will be useful in developing necessary control methods for Rice crown and root rot disease.

Crowds of the false chinch bugsNysius cymoides appear in many canola fields of the country at pod ripening stage. To develop sequential sampling plans for eggs, immature stages and adults of the bug, samples were taken during two years from a canola field in the Broojerd Agricultural Research Station. Samples were randomly collected twice a week using a 5 × 5 cm quadrat and an aspirator. Then, the specimens were carried to the lab in alcohol tubes for counting the different stages. Taylor’s power law parameters were used to create Green’s sequential sampling plans at 10, 15 and 25 percent precision levels. The results showed that sample size for eggs was larger than nymphs and adults for different levels of precision. Sample sizes were dramatically reduced by increasing population density in different sequential models. Generally, sequential sampling models at 25 percent precision level are recommended for monitoringN. cymides populations due to reducing sample sizes to less than half, compared with those at 15 percent precision level. However, the 10 percent precision level models were not applicable because of large sample size estimations.

Melon is a valuable crop in agriculture. Several pests are effective in reducing production. In order to reduce the use of chemical insecticides in melon fields and improve non-chemical methods, Kurkmelon (Cucumis melo var. flexuosus) and Samsoori muskmelon (Cucumis melo var. reticulata) were chosen as a trap crop for some of pests. This research was carried out with randomized complete block design in three replications and various ratios of melon bushes to trap crops. The results showed that, trap crops were able to reduce the damage of all important melon pests according to the type and the number of trap crops in experimental plots and increased the amount of healthy product at 17.92-36.12% (13.9-30.76% for Baluchistan melon fly, 8.14-12.24% for lesser pumpkin fly and 5.67-8.69% for cucurbit weevil in comparison with check treatment.

In this study, infected seeds of pasture legume plants (Fabaceae) were collected from different regions in East-Azarbayjan province during 2010-2013. Host plants and their seed feeder pests were determined by field collecting and laboratory rearing of insects on the respective hosts. Thus, a total of 124 legume specimense (belonging to 32 species) were collected from 7 sites across rangelands of which 71 specimense (belonging to 26 species) was positive for seed-eating insects. Based on identification study, many extracted granivores from infected seeds, were Hymenoptera and Coleoptera. Among the seed-eating species, 13 Bruchidae species belonging to 3 genera (Bruchidius, Bruchus and Paleoacanthoscelides) were identified as follows: Bruchidius annulicornis (Allard), Bruchidius longulus Schilsky, Bruchidius nanus(Germar), Bruchidius pusillus (Germar), Bruchidius sp., Bruchus nikdeli Delobel & Sadeghi, Bruchus emarginatus Allard, Bruchus hamatusMiller, Bruchus concinnus Klug, Bruchus sibiricus Germar, Bruchus libanensis Zampetti, Bruchus lugubris Fahraeus, Paleoacanthoscelides gilvus(Gyllenhal).