Influência da infestação de Oligonychus ilicis (McGregor, 1917) (Acari: tetranychidae) sobre a taxa de fotossíntese potencial de folhas de cafeeiro

Abstract

Oligonychus ilicis (McGregor, 1917), is one of the main phytophagous mites of the coffee plant (Coffea spp.), although it is not reported among the primary pests. They live on the upper surface of the leaves, puncturing the epidermis and mesophyll cells to absorb and feed on the extravasated cellular content. In consequence, the leaves lose their natural shine and become tan. The objective of this work was to quantify the photosynthetic rate of coffee-plant leaves presenting different infestation levels of O. ilicis. The study was carried out in potted three-year-old coffee plants (Coffea arabica L., Catuaí cultivar), kept in a greenhouse. Infestations were accomplished at five different levels (0, 15, 30, 60 and 120 adult mite females/leaf), with mites coming from a stock rearing, on leaves of the third pair starting from the apex and totally expanded, located in branches from the middle third of the plant, with five repetitions. The potential photosynthesis was measured through the photosynthetic oxygen produced, using an oxygen monitor with a Clark type electrode coupled to a CB1 electric flow control box. The evaluations were made 7 and 21 days after the infestation with the mites, and the data obtained were submitted to regression analysis. There was a negative correlation between levels of infestation and potential photosynthesis, whereas at levels 15, 30, 60 and 120 mites/leaf, the photosynthetic rates were reduced in relation to the control treatment, in 37.2, 38.7; 46.0 and 50.1% respectively.