Comparison of the susceptibility of several cultivars of avocado to the persea mite, Oligonychus perseae (Acari: Tetranychidae)

We compared the susceptibility of seven cultivars of avocado, Persea americana, to feeding by Oligonychus perseae. Based on the percentage of leaf area damaged by mites in February 1998, cultivars were categorized into three groups: Hass and Gwen were `susceptible', Fuerte, Lamb Hass and Reed were `resistant', Esther, and Pinkerton were of `intermediate' susceptibility. A life table study in the laboratory showed no difference in mortality and rate of development of O. perseae of either the ®rst or second generation reared on either Hass, Pinkerton or Lamb Hass cultivars. Although O. perseae exhibited no difference across cultivars with respect to reproductive rates when reared on leaves collected in late spring (April) and early summer (June), net reproduction and intrinsic rate of increase were signi®cantly higher on Hass avocados in mid summer (July). A corresponding increase in percentage leaf area damaged by mite feeding was also observed in the ®eld on Hass in July. We suggest that seasonal changes in the nutritional quality of leaves may be the major factor determining susceptibility of avocado cultivars to O. perseae. # 2000 Elsevier Science B.V. All rights reserved.