Sublethal effects of flonicamid and dichlorvos insecticides on life-table parameters of the melon aphid Aphis gossypii(Hemiptera: Aphididae) under greenhouse conditions

Abstract

Aphis gossypii Glover is considered as the most important and damaging pest with wide host range and distribution on plants in fields and greenhouses. Common cotton aphid management in fields depends on the use of chemical insecticides in order to prevent economic damage. In the present study, lethal and sub-lethal concentrations of flonicamid and dichlorvos insecticides were assessed through bioassays and the effect of sub-lethal concentrations (LC10 and LC25) of each of them was investigated on life table parameters of cotton aphid on pinto beans under greenhouse conditions. Considering the contact effect of these insecticides, the insecticide spraying method was used on leaves containing aphids. According to the results, the female lifespan/longevity was significantly reduced by sub-lethal concentration, compared to the control and its lowest value (7.42 days) was recorded in LC25 concentration of flonicamid. The average number of nymphs produced per female aphid was significantly reduced in the treatments compared to the control. The highest and the lowest values of intrinsic rate of increase (r) were 0.38 per day in control and 0.21 per day in LC25 of flonicamid, respectively. A significant decrease was observed in sub-lethal concentrations of insecticides compared to the control in net reproductive rate (R0) and finite rate of increase (). The mean generation time (T) was significantly increased in flonicamid treatment compared to the control. Based on the findings of the present study, flonicamid had a better and more efficiency in controlling and reducing the population of aphids compared to dichlorvos.

Keywords

• chemical insecticides
• life table
• aphid
• lethal and sub-lethal