جستجوی مقالات مرتبط با کلیدواژه "pymetrozine" در نشریات گروه "گیاهپزشکی"

Wheat is the most important strategic crop in Iran and the world. Sunn pest Eurygaster integriceps Puton (Hemiptera: Scutelleridae) causes a lot of damage annually. Currently, two groups of IRAC insecticides including pyrethroids and organic phosphorus compounds are recommended against this pest in Iran and other countries infested with the Sunn pest. In this research, different insecticides were selected from the eight insecticide groups of IRAC, and contact bioassay was carried out on two life stages of the Sunn pest. The results showed that among the tested insecticides, Deltamethrin (LC50=2.93 mg a.i./L) as a pyrethroid group, had the most contact toxicity among chemical compounds against overwintered adults of the Sunn pest, and Fenitrothion as an organic phosphorus compound  (LC50=19.4 mg a.i./L) was ranked in the second group. But on the new generation of the Sunn pest, both insecticides were ranked in the same group at 72 hours after exposure (LC50=4-4.6 mg a.i./L). Further investigations revealed that among neonicotinoid insecticides, Thiamethoxam had more contact toxicity and ranked in the next group. Mortality comparison of different insecticides in high concentration (60-20000mg/L) based on commercial formulations showed that Deltamethrin and Fenitrothion insecticides caused 90-100% mortality in both life stages of the Sunn pest. The new insecticides, Spirotetramat, Flonicamid, and Chlorantraniliprole did not show acceptable effectiveness 72 hours after exposure on overwintered and new-generation adults (3.3-43%). Therefore, most of the new insecticides tested for the chemical control of the overwintered and the new generation adults did not have acceptable mortality, and only thiamethoxam insecticide can be studied on Sunn pests in field conditions.

Due to various economical and health drawbacks of high pesticide residue levels, monitoring them on food stuff is very important. In the greenhouses of Isfahan province various pesticides are being used of which highest consumption and toxicity is of the insecticides, therefore presence of high residue levels on their products is not far from expectation. To trace the residue levels of four insecticides (Dichlorovus, Deltamethrin, Imidacloprid and Pymetrozine) on cucumber, samples were collected every thirty days from the greenhouses of four cities, Falavarjan (4 greenhouses), Esfahan (4 greenhouses), Dehaghan (2 greenhouses) and Shahreza (2 greenhouses) during the cultivation season. A total of 192 samples (combination of greenhouse, Insecticide, City) were collected and analyzed. Samples collected from Isfahan city showed levels of Dichlorovus, Deltamethrin, Imidacloprid and Pymetrozine to be 70, 55, 12 and four times the Maximum Residue Levels (MRLs) respectively. Similarly high levels of Dichlorovus and Imidacloprid were detected on the samples of other cities. Percentages of highly contaminated samples with all four insecticides in different cities were 34, 39, 34 and 46 for Isfahan, Falavarjan, Shahreza and Dehaghan cities respectively. Therefore it is clear that all the cities have about 35-45 percent of their cucumber samples under investigation having insecticide residue levels higher than the MRLs. Overall the results show that in Isfahan, Falavarjan, Shahreza and Dehaghan about 33, 33, 35 and 41 percent of the samples analyzed have higher levels of one or more insecticides checked higher than the MRLs respectively. Therefore consumption of this produce could be a threat to the health of the consumers.