Assessment of cotton aphids, Aphis gossypii, and their natural enemies on aphid‐resistant and aphid‐susceptible wheat varieties in a wheat–cotton relay intercropping system

Abstract

The cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), is an important cotton pest in northern China, especially in the seedling stage of cotton. After large scale commercial use of transgenic Bt cotton, cotton aphids became one of the most important cotton pests. A 2‐year study was conducted to evaluate the role of four winter wheat varieties that were resistant or susceptible to wheat aphid, Sitobion avenae Fabricius (Homoptera: Aphididae), in conserving arthropod natural enemies and suppressing cotton aphids in a wheat–cotton relay intercropping system in northern China. The results indicated that wheat–cotton intercropping preserved and augmented natural enemies more than a monoculture of cotton. The density of natural enemies in cotton was significantly different among relay‐intercropping fields with different wheat varieties. The highest density of natural enemies and low cotton aphid populations were found in the treatment of cotton in relay intercropped with the wheat variety Lovrin10, which is susceptible to wheat aphid. The lowest density of predators and parasitoids associated with high cotton aphid populations were found with the wheat variety KOK1679, which is resistant to wheat aphid. The results showed that wheat varieties that are susceptible or moderately resistant to wheat aphid might reduce cotton aphids more effectively than an aphid‐resistant variety in the intercropping system by enhancing predators to suppress cotton aphids during the cotton seedling stage.

Influence of Garlic Intercropping or Active Emitted Volatiles in Releasers on Aphid and Related Beneficial in Wheat Fields in China

“…In addition, it is important to take the resistant levels to aphids of a host plant into consideration. In an intercropping system, wheat varieties that are susceptible or moderately resistant to cereal aphids may reduce cotton aphids more effectively than an aphid-resistant variety by enhancing predators to suppress cotton aphids during the cotton seedling stage (Ma et al 2006). However, volatiles produced by non-host plants often affect the behavior of pests and their natural enemies, these may vary genetically among plants (Bai et al 2011).…”

Crop Diversification Affects Biological Pest Control

“…Intercropping or mixing different crops as a traditional agricultural technique is used for preventing pest infestation in different world geographical areas (Ma et al, 2006). The plant components of intercropping system do not necessarily have to be sown at the same time, but they should be grown simultaneously for a substantial part of their growth periods (Andrews & Kassan, 1976).…”

Temporal allocation of metabolic tolerance to transgenic Bt cotton in beet armyworm, Spodoptera exigua (Hübner)

“…When ingested by larvae, toxin proteins bind to specific receptors in the midgut region, and toxin binding in susceptible insects disrupts the midgut epithelium, thereby causing overall toxic effects and ultimately resulting in larval death [8]. Transgenic Bt cotton that expresses the Cry1Ac toxin is highly effective against the major lepidopterous cotton insect pests [9]. Multiple field trials have proven that Bt cotton exhibits high insecticidal efficacy against larvae of tobacco budworm, cotton bollworm and other target lepidopterous pests and decreases the population densities of these target pest species in cotton fields [10][11][12].…”