Metasequoia glyptostroboides Hu et Cheng, a rare deciduous conifer of the redwood family (Cupressaceae), was discovered from fossil material (Miki 1941) and formally described in scientific literature as a new, existing species in 1948 (Hu & Cheng 1948). Though with a limited natural range in western Hubei, northern Hunan and eastern Sichuan provinces in central China (Chu & Cooper 1950; Bartholomew et al. 1983), the species is at present planted throughout the world in botanical gardens and arboreta from as far north as Scandinavia to as far south as New Zealand (Satoh 1999). The genus Brevipalpus have attracted extensive attention worldwide for their involvement in vectoring plant viruses (Chagas et al. 2003; Childers et al. 2003; Kondo et al. 2003; Rodrigues et al. 2003) since their first description by E.W. Baker (1949). Among the 16 species known in China (Zhang 2010), Brevipalpus lewisi McGregor (Acariformes: Tenuipalpidae) is reported to be widely distributed in China, USA, Cuba, Japan, Egypt, Mexico, Spain, and Australia (Wang et al. 1981; Deng et al. 1989; Kerns et al. 2004; Lewis 1949; Rodriguez et al. 1987), with an extensive host range of citrus (Lewis 1949; Elmer & Jeppson 1957), pomegranate (Ebeling & Pence 1949), walnuts (Michelbacher 1956), grapes (Buchanan et al. 1980; Arias & Nieto 1985), and pistachios (Rice & Weinberger 1981).
Brevipalpus lewisi has been known as a pest of grapes in northern China such as Liaoning, Hebei, Shandong and Henan (Wang 1981; see also the review in Zhang 2010). However, in 2009, B. lewisi was found for the first time infesting M. glyptostroboides and inflicting considerable economic damage to the cities of Shanghai, Nanjing, and Wuhan in eastern China. The symptoms observed on the infested plants were leaf spots, color change from yellowish to brownish, as well as large numbers of mites and their exuviae on the lower surfaces of leaves (Fan et al. 2010).
Overwintering adult female B. lewisi feed on the new lower leaf surface of M. glyptostroboides and aggregate along the mid-vein in mid-May, depositing oval reddish eggs on the petiole in four to eight clusters. The population markedly decrease during the Meiyu season (East Asian rainy season) of June and early July, but increase and disperse over the plants in late July and early August. Afterwards, the population grow quickly and reach the highest density in late September. Finally, in late November, the adult female mites overwinter in the leaf sheath of current-year and one-year-old twigs. Premlinary observations suggest B. lewisi developmental rates are strongly influenced by the environmental conditions, especially temperature and rainfall. Dry and low-rainfall make the mites most virulent, leading to the outbreak period from August to October.
The cover image shows four active stages of B. lewisi growth: larva, protonymph, deutonymph, and adult. A physiologically active resting period exists between each active stage. The female adult is usually rufous amber in color with black pigmentation, while immature flat mites are slight red. B. lewisi reproduce by thelytokous parthenogenesis (Buchanan et al.1980), with females producingfemales and no males were found. Reference specimens are deposited in the Entomology Specimen Room of Nanjing Forestry University, and some specimens were also in Institute of Zoology, Chinese Academy of Sciences, Beijing.
We thank two anonymous reviewers and Dr Zhi-Qiang Zhang for the improvement to this paper.
