Differences in Thrips¹ Population Density Under Different Spatial Arrangements of Mexican Marigold and Tomatillo

Tomatillo (Physalis philadelphica Lam) is native to the Americas, and thrips (Thysanoptera: Thripidae) are one of its main phytosanitary problems. These insects reduce yields by damaging photosynthetic capacity of leaves. Severe infestations also lead to floral buds remaining closed and drying prematurely. Thrips are generally controlled using synthetic insecticides and biological control. A possible additional measure of control is the use of spatial arrangements in combination with attractive or repellent plants, such as the Mexican marigold (Tagetes erecta L.). We evaluated the population dynamics of thrips on T. erecta and P. philadelphica in monoculture and in association with each other in three spatial arrangements in two localities in the Toluca Valley. Thrips abundance was greatest in T. erecta monoculture, significantly more than in P. philadelphica in monoculture, or in any of the spatial arrangements. All spatial arrangements had greater tomatillo yield compared to monoculture. We conclude that T. erecta acts as a natural attractant plant for thrips during all phenological stages of the life of the plant.