Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/25/2007
Publication Date: 1/8/2007
Citation: Skoracka, A., Kuczynski, L., Rector, B.G. 2007. Divergent host-acceptance behavior suggests host specialization in populations of the polyphagous mite Abacarus hystrix (Acari: Prostigmata: Eriophyidae). Environmental Entomology. 36(4):899-909. Interpretive Summary: The grain rust mite, Abacarus hystrix, is a pest of many cereal crops and has been recorded from more than 70 different plant hosts in the grass family. Recently, two populations of this mite, which were collected in western Poland on ryegrass and quackgrass, have been found to be much more host-specific than what would be expected in such a highly polyphagous species or what had previously been observed for this species in particular. This study used behavioral data to assess the host specificity of these two populations. The data show that each population is much less accepting of the other population's host plant in comparison to its own, familiar host plant. In conclusion, the authors propose that these two populations of the grain rust mite be considered as host races. Implications on host-acceptance behavior, host-specificity, speciation are discussed.
Technical Abstract: For phytophagous arthropods, host-acceptance behavior is a key character responsible for host-plant specialization. The grain rust mite, Abacarus hystrix (Nalepa), is an obligately phytophagous, polyphagous eriophyid mite recorded from at least 70 grass species. In this study the hypothesis that two host populations of this mite (one collected from quackgrass, the other from ryegrass) are highly host-specific was tested using behavioral data. For this purpose, female behavior when exposed to familiar and novel host plants was observed in no-choice cross experiments. Altogether, 13 variables were used to describe mite behavior. Data were subjected to Principal Component Analysis and host-acceptance behaviour was subsequently tested with Generalized Estimating Equations (GEE). Distinct variation in female behavior between familiar and novel hosts was observed. Females from neither population accepted novel hosts. This was recorded as significant differences in the occupation of and overall activity on particular plant parts. On the familiar host females were not very active and showed little tendency to move. On novel hosts females were more active and mobile, spent more time walking, running and climbing on the whole plant surface, and showed a tendency to disperse. Differences in behavior between ryegrass and quackgrass populations were also observed. Thus, the results suggest that mites of these two populations 1) differ in their behaviors during plant exploitation, and 2) can quickly distinguish between their familiar host and that used by the other population. These findings support the hypothesis of narrow host specialization of ryegrass and quackgrass populations of this highly polyphagous species.