The Parasitoid Eretmocerus hayati Is Compatible with Barrier Cropping to Decrease Whitefly (Bemisia tabaci MED) Densities on Cotton in China.

The whitefly, Bemisia tabaci (Gennadius) cryptic species Mediterranean (MED), is a destructive insect pest worldwide. In order to contribute to controlling B. tabaci by non-chemical methods, we examined the possibility of using a combination of trap/barrier crops and a parasitoid natural enemy in cotton. We performed field experiments using cantaloupe (Cucumis melo) and sunflower (Helianthus annuus) as trap crops and maize (Zea mays) as a barrier crop combined with periodic releases of the parasitoid Eretmocerus hayati in Hebei Province, Northern China. All treatments significantly reduced immature whitefly densities. Parasitism rate was significantly higher in cotton plots intercropped with sunflower and with perimeter-planted cantaloupe. Adult whitefly density was negatively related to parasitoid abundance and was significantly lower in cotton plots intercropped with maize than in the control plots. Intercropping was more effective than perimeter-planting at reducing B. tabaci densities and increasing yield. Parasitoid dispersal was not hampered by barrier crops, indicating that the two methods of control are compatible. These results contribute to the development of integrated pest management methods against this important pest.

The potential of trap and barrier cropping to decrease densities of the whitefly Bemisia tabaci MED on cotton in China.

BACKGROUND: The whitefly, Bemisia tabaci (Gennadius) MED, is a destructive insect pest in many countries of the world. Although the use of insecticides for controlling B. tabaci has been effective to a certain extent, pesticides are not an acceptable long-term control method, and alternatives should be sought. This paper focuses on the possibility of controlling B. tabaci on cotton using trap and barrier crops. We performed field experiments using cantaloupe (Cucumis melo) and sunflower (Helianthus annuus) as trap crops, and maize (Zea mays) as a barrier crop in various configurations in Hebei Province, North China. RESULTS: The main activity periods were shortest on cantaloupe and ranged between 16-32 days for immatures and 14-33 days for adults. Adult whitefly densities were not significantly reduced by any treatment. During the main activity period, maize intercropping reduced densities of immature whiteflies from 24.2 individuals (ind.) 100 cm-2 to 4.0 ind.100 cm-2 , but all treatments were successful in significantly reducing immature B. tabaci densities. This resulted in a significant yield premium. CONCLUSIONS: Intercropping reduced B. tabaci densities on cotton more than perimeter planting. Maize was more effective to reduce densities of immature whiteflies on cotton than cantaloupe. The results will contribute to the development of more effective and practical approaches for protecting cotton from B. tabaci and lowering chemical pressure on this crop. © 2019 Society of Chemical Industry.