Common name: Citrus bud mite.
Geographical distribution: Almost wherever citrus is grown. Commonwealth Institute of Entomology Map #127, 1980 (revised).
Host plants: Citrus spp., especially lemons
Symptoms and economic importance: The bud mites lives in and feed on the buds, blossoms and flowers of the host. They sometimes occurs in very large numbers. Their feeding kills the cells and causes the blackening of the buds and irregular growth of leaves, branches and fruit. The damaged buds proliferate and produce irregular and twisted growth of leaf clusters. Twigs are foreshortened and broomed and the fruit deforms into various distorted shapes, including finger-like forms. Further damage is caused by fruit drop. Although the pest attacks all citrus varieties, it causes the most serious damage to lemons, whose yield may be seriously affected.
Morphology: The body of the adult citrus bud mite is yellow to pink, about 0.17 mm in length, cylindrical, with a similar number (70-80) of dorsal and ventral opisthosomal rings. The prodorsum bears a pair of backwards-pointing setae and two parallel ridges along its entire length. The featherclaw is five-rayed.
Life cycle: The citrus rust mite reproduces by arrhenotoky, each female deposits about 50 eggs, and its entire cycle (egg to egg) requires about 15 days in summer, twice that much in winter. The pest thus raises about 20 annual generations. The sex ratio is male-biased in spring and female-biased during fall. Although the mite lacks eyes, it is attracted to yellow and red, not to blue or green. The pest develops throughout the year, mostly in milder and more humid regions, with peaks in the spring and autumn. Dispersal takes place during the spring growth of most citrus trees and the several growth flushes of lemons. Young, elongating twigs are rapidly colonized by the mite, its infestations increasing as the twigs age. Temperatures below 8°C or above 35°C, and relative humidity below 40% are lethal to the mite.
Chemical control: When necessary, the mite can be controlled by most acaricides as well as by white oil, but the cost of such control may exceed the its economic benefit.
Biological control: Several predatory mites have been found to be associated with the citrus bud mite, but due to being protected inside the buds, none appear to effect the populations or the damage caused by the pest.
Sternlicht, M. 1969. A study of fluctuations in the citrus bud mite population. Annales de Zoologie-Écologie animale 1: 127-147.
Sternlicht, M. 1969. Effect of different wave lengths of light on the behaviour of an eriophyid bud mite, Aceria sheldoni. Entomologia Experimentalis et Applicata 12: 377-382.
Sternlicht, M. and Goldenberg, S. 1971. Fertilisation, sex ratio and postembryonic stages of the citrus bud mite _ Aceria sheldoni_ (Ewing) (Acarina, Eriophyidae). Bulletin of Entomological Research 60: 391-397.
Walker, G.P., Voulgaropoulos, A.L. and Phillips, P.A. 1992. Effect of citrus bud mite (Acari: Eriophyidae) on lemon yields. Journal of Economic Entomology 85: 1318-1329.
Walker, G.P., Voulgaropoulos, A.L. and Phillips, P.A. 1992. Distribution of citrus bud mite (Acari: Eriophyidae) within lemon trees. Journal of Economic Entomology 85: 2389-2398.