Is the cereal rust mite, Abacarus hystrix really a generalist? - Testing colonization performance on novel hosts

Area of Science:

• Agricultural Entomology
• Plant-Insect Interactions
• Eriophyoid Mite Biology

Background:

• Eriophyoid mites typically exhibit high host specificity.
• The cereal rust mite (Abacarus hystrix) has been considered an exception, with a broad host range.
• Its vagrant nature and aerial dispersal led to its classification as a host generalist.

Purpose of the Study:

• To test the hypothesis that Abacarus hystrix populations are specialized on local host plants, potentially representing distinct host races.
• To investigate the host specificity of A. hystrix beyond its commonly perceived generalist nature.

Main Methods:

• Females of A. hystrix from two host populations (quack grass and ryegrass) were experimentally transferred to their native and novel host plants.
• Mite survival and fecundity (fitness) were assessed on both normal and novel host plants.

Main Results:

• A. hystrix females failed to colonize novel host plants.
• Significantly higher survival and fecundity rates were observed on the normal (native) host compared to the novel host.
• Results align with observations of host-dependent phenotypic variation and acceptance.

Conclusions:

• Abacarus hystrix populations demonstrate significant specialization to their local host plants, challenging the host generalist view.
• These findings suggest A. hystrix may comprise a species complex of highly specialized host races.
• This specialization has implications for understanding host specificity in eriophyoid mites and the viruses they transmit.