Incidencia de trips y mosca blanca en tomate de cáscara (Physalis philadelphica L.), solo y en asociación con cempaxóchitl (Tagetes erecta L.)

Abstract

The tomatillo (Physalis philadelphica L.) is an important vegetable in the mexican diet; in 2017, 43,172.56 ha were planted in Mexico, with Sinaloa as the main producer. Tomatillo production faces phytosanitary problems including thrips (Frankliniella occidentalis) and whitefly (Bemicia tabaci L.). Thrips are small insects, measuring 0.8 to 3 mm long, that over the last few decades have become the main insect pest worldwide for several horticultural, agricultural, and ornamental crops. The genus Frankliniella is the largest in the family Thripidae. Whitefly is a disease vector for the tomatillo, and for that reason is a pest that requires careful attention and control. One of the main causes of pest increase is the expansion of monocultures and frequent use of synthetic agrochemicals that affect beneficial and entomophagous insects. One of the control measures used in agroecological management is the diversification of crops in a given space, including the use of associated crops, polyculture, and other alternatives such as living fences, repellent crops, attractants or trap plants, etc. In horticulture, these alternatives are infrequently, used especially in open-air crops. With the objective of quantifying the repellent or attractant effect on thrips and whitefly of tomatillo in association with Mexican marigold, an experiment was carried out in the summer of 2019 to determine the density of both insects in tomatillo in monoculture, tomatillo in association with Mexican marigold, and Mexican marigold in monoculture. Using the data of density by sampling date, we estimated the progression of the pest population over time using the program R. A completely randomized block experimental design was used to distribute the four treatments and ten experimental units. In each experimental unit a monochromatic (yellow) trap was placed to capture insects and estimate their density by date and area under the curve, as well as the final tomatillo yield. The density by date data as well as the final area under the curve value were analyzed using SAS. The results showed that thrips had a preference for Mexican marigold in monoculture during the whole growing cycle, compared to the other treatments, since this insect had both a larger population and higher area under the curve value in this treatment. Meanwhile, the tomatillo in monoculture had the lowest thrip population and lowest area under the curve. In whitefly, there was no attractant or repellent effect, allowing us to conclude that Mexican marigold is a natural attarctant for thrips, but not for whitefly. The tomatillo yield was not affected by the treatments, though the tomatillo in monoculture had a numerically higher yield.