Population Fluctuations of Thrips (Thysanoptera) and Their Relationship to the Phenology of Vegetable Crops in the Central Region of Mexico

Abstract

The presence of thrips in vegetable crops has become an important phytosanitary issue in Mexico. Their direct injuries to plants are the result of the feeding by their immature and adult stages, whereas their indirect injuries are caused by the transmission of various viruses. The objective of this study was to identify the species of thrips associated with 6 vegetable crops in order to determine their population fluctuations and to ascertain the effects of temperature and rainfall on their populations. Samples were collected from zucchini, onion, pepper, cucumber, tomato, and tomatillo in Puebla and Morelos from Feb 2010 to Feb 2011. Three species were identified: Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) on all vegetables, Frankliniella fortissima (Priesner) on zucchini and cucumber, and Thrips tabaci (Lindeman) (Thysanoptera: Thripidae) on onion and pepper. The highest population level for thrips coincided with the presence of flowers on the crops, except in the case of onion. In general, 2 to 6 generations of thrips were present in each crop cycle, and the levels of populations decreased when the plants were near senescence. The main suppressive effect of weather on thrips populations was caused by rainfall.