Host plant acceptance by the phytophagous mite Tetranychus kanzawai Kishida is affected by the availability of a refuge on the leaf surface

We used 11 wild plants to experimentally test the effects of leaf trichomes and leaf quality on host plant acceptance by a phytophagous spider mite, Tetranychus kanzawai , in the absence of predators. There was a positive correlation between leaf hair traits (height/density) and host plant acceptance. We used two model plants ( Phaseolus vulgaris and Phaseolus lunatus ; the former had higher and denser leaf hairs than the latter) to examine the effects of leaf hairs on the dispersal and fecundity of T. kanzawai in the presence of a predatory mite, Neoseiulus womersleyi . In the presence of N. womersleyi , significantly fewer T. kanzawai females dispersed from a P. vulgaris leaf than from a P. lunatus leaf. Moreover, in the presence of the predator the fecundity of T. kanzawai females on P. lunatus was significantly lower than on P. vulgaris , although in terms of host quality the two plants were equivalent. In the presence of N. womersleyi , T. kanzawai females on P. vulgaris spent more time on webs than those on P. lunatus . Moreover, webs seemed to be less accessible than leaf surfaces to the predator. These results suggest that leaf hairs provide a refuge for T. kanzawai adult females.