Physiological Responses of Avocado Leaves to Avocado Brown Mite 1 Feeding Injury

Effects of various levels of feeding injury caused by the avocado brown mite, Oligonychus punicae (Hirst) (Acari: Tetranychidae), on avocado leaves were examined. Mite feeding from the upper leaf surface reduced chlorophyll content of the upper mesophyll layer of avocado leaves, whereas chlorophyll content remained unchanged in the lower spongy parenchyma layer. Stomatal and mesophyll conductance values, photosynthesis, and transpiration were found to be negatively correlated with increasing levels of spider mite injury. Avocado photosynthesis rates were reduced 56% when 100% feeding injury was sustained on the upper leaf surface.