The effect of intercropping of tomato and clover on control of melon aphid, Aphis gossypii Glover

Background and Objectives:

 The melon aphid, Aphis gossypii Glover, is one of the most important pests of tomato in Iran. This aphid causes severe damage on tomato crop in northern Iran. 

Materials and Methods:

 Present study was conducted in an experimental field, 0.3 h, in Behshahr region in Mazandaran province based on a randomized completely block design. In this study, the effectiveness of intercropping tomato (T) with clover (C) in the three combinations: (1) one row of tomato with two rows of clover (1T:2C), (2) two rows of tomato with two rows of clover (2T:2C), and (3) three rows of tomato with two rows of clover (3T:2C) along with sole tomato were assessed on the densities of melon aphid, Aphis gossypii Glover, diversity of its natural enemies and yield of both crops in 2016 and 2017.

 Results:

 The density of nymphs and adults of A. gossypii were significantly higher in sole tomato compared with intercrops. Among intercrops, the lowest density of nymphs and adults of A. gossypii were observed in 1T:2C intercrop. In present study, 13 predator species were collected and identified on aphid-infested plants of tomato in the experimental field. Among the predators, Coccinella septempunctata L., Chrysoperla carnea (Stephens) and Episyrphus balteatus DeGeer had more abundance in the two studied years.  The Shannon diversity index (H´) and the Pielou’s evenness index (J´) for composition of predator species were significantly higher in intercrops compared with sole tomato crop. Moreover, more nymphs and adults of A. gossypii were parasitized in all intercrops compared with sole tomato crop in 2016 and 2017. The highest value of land equivalent ratio was found in 1T: 2C (LER = 1.28 in 2016 and 1.30 in 2017) among intercrops in the two cropping seasons.   

Discussion:

 All the three intercropping patterns of tomato with clover including 1T:2C, 2T:2C and 3T:2C, especially 1T:2C could be recommended in management programs of the melon aphid in tomato fields.