부산대학교 도서관

Lorryia formosaCooreman (Acari: Tydeidae) is a species of mite commonly associated with citrus in many countries including the United States. A survey report in 1957 suggested phytophagous nature, while other studies claimed that L. formosapopulations are associated with honeydew producing insects and sooty mold and it acts as a sanitizing agent. We investigated the effect of various diets on the survival and progeny production of L. formosaon excised leaves and the survival and potential to cause feeding damage to leaves of potted plants in a greenhouse study. A 2-yr field survey of a mandarin orchard was also conducted to elucidate the seasonal infestation, damage potential and population structure of L. formosain a natural habitat. Results showed that all L. formosaadults and immatures died in less than 14 d on excised leaves, did not survive beyond 7 d on potted citrus plants alone, and caused no observable feeding damage to leaves or fruit. When sugar water, honeydew, or cottony cushion scale, Icerya purchasiMaskell (Hemiptera: Margarodidae), was present, adults and immatures survived the duration of the experiments and produced additional generations. The field survey showed that all stages of L. formosawere present in a mandarin orchard throughout the year and insecticide applications affected but did not eliminate mite populations. Fruit generally had a greater percentage infestation of mites (44.8 ± 4.0) than leaves (16.0 ± 4.7). These studies confirmed that L. formosacannot sustain a population on leaf tissue alone and is nondamaging to citrus in California.