Intercropping garlic at different planting times and densities for insect pest or crop yield and value management in tobacco fields

Although the densities of tobacco pests have been decreased in garlic-tobacco fields, further studies are needed to judge the effects of garlic transplanting densities or times on tobacco pests in tobacco fields. Therefore, field experiments were conducted in Liancheng County in Longyan City, Fujian Province, in China in 2014 and 2015. Myzus persicae (Sulzer) abundance, the species or abundance ratios of enemies and pests, the intercropping effects and the tobacco yield and crop value showed that the effects of transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter on pests were stronger than those of other treatments. Aphid abundance was significantly lower in transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter than in the other treatments. The ratio between enemies and pests in transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter was higher than those in the other treatments. The intercropping effects of transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter on Myzus persicae, Spodoptera litura (Fabricius), Heliothis assulta Guenee and Nezara viridula Linnaeus were significantly stronger than those of the other treatments, whereas the effects of transplanting tobacco 15 days after garlic transplantation at a garlic density of 5.85 individual plants per square meter on Agrotis ypsilon (Rottemberg) were significantly stronger. Additionally, the yield and crop value of transplanting tobacco 10 days after garlic was transplanted at a density of 5.85 individual plants m(-2) were higher than those of the other treatments. Therefore, our study demonstrated that the model of transplanting tobacco 10 days after garlic was transplanted at a density of 5.85 individual plants m(-2) is an optimal management strategy to control flue-cured tobacco pests and to acquire higher crop yield in garlic-tobacco fields.