Effect of salicylic acid and two pepper cultivars on population growth of Aphis gossypii (Hem.: Aphididae)

The melon aphid, Aphis gossypii Glover is one of the most important pests in pepper fields and greenhouses, which is of special economic importance due to its wide distribution and large host range. In this research, biological and reprodutive parameters of A.gossypii on two pepper cultivars (Poblano and Paprika) treated with salicylic acid, were investigated at laboratory conditions (25 ± 2 ˚C, 65 ± 5 % RH, and a photoperiod of 16L: 8D h). According to the results, the use of salicylic acid in both cultivars had a significant effect on most of the demographic parameters of the A.gossypii, compared to the control (spraying with distilled water) and decreased its life span, life cycle length, and Survival. The lowest and highest lifespan were 5.91 days (salicylic acid treatment in Paprika) and 10.25 days (control treatment in Poblano), respectively. Also, the use of this hormone had a significant effect on the reducing gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of the aphid. The minimum and maximum values of r  were obtained in salicylic acid treatment on Paprika and control treatment on Poblano (0.2570 and 0.4046 d-1 respectively). So, salicylic acid can considerably reduce biological and reprodactive parameters of A.gossypii in pepper and can be used in integrated pest management programs of melon aphid.