Populational fluctuation of tomato leafminer in the sub-meddle São Francisco Valley

Abstract

The tomato leafminer Scrobipalpula absoluta (Meyrick, 1917) (Lepidoptera, Gelechiidae) has caused severe damages to tomato crop in the sub-middle region of the São Francisco Valley (Petrolina, Pernambuco State, Brazil). Some studies were carried out to determine the tomato leafminer populational fluctuation and its relations to temperature, air relative humidity, rainfall, wind speed and solar radiation. Tomato crop, variety IPA-2, was planted in a 500 m² plot every month from April 1983 to September 1984. Weekly sampling, beginning 20 days from transplanting the seedlings, was made to evaluate the number of eggs and larvae of S. absoluta. The pest populational was evaluated by sampling 90 folioles from the upper, the middle and the lower parts of the plants and 100 fruits picked out at random in each harvest. Among the climatic parameters studies it was observed that the rainfall had the greatest influence on the populational fluctuation of S. absoluta. The pest attack was more intense in July, August and September when rainfall in the region is very low.