In most cases, these studies involved lepidopteran species with a broad host range (generalists) such as Spodoptera exigua or Trichoplusia ni, and found that generalist insects were sensitive towards glucosinolate-based defenses.
The Metarhizium species complex is diverse, including generalist species with a broad host range and specialist species with narrow host ranges.
One of these strains is a generalist with a relatively broad host range, encompassing mammal species from a wide taxonomic spectrum.
By characterizing the molecular signature of host-parasite interactions, we stand to gain insight into the processes underway in a generalist parasite that facilitate a broad host range and learn about the molecular mechanisms that can facilitate the generalist parasite strategy.
The generalist fur flea with a narrower host range, L. agrippinae, displayed geographic mtDNA spatial genetic structure at the regional scale and this pattern is congruent with host vicariance.
The difference in genome size and protein-coding gene set complexity could be a cause or consequence of the differences in host range (specialist vs. generalist) and tissue tropism (narrow vs. broad).
Ordinarily, it is expected that a restriction in host range from a generalist such as C. parvum to a specialist such as C. hominis may be accompanied by selective loss of alleless; however, this study identified 334 putatively C. hominis-specific genes and 178 C. parvum-specific genes.
B. betularia definitely fulfills this prediction of wide host range: caterpillars are generalists and can rear off a tremendous range of host trees and shrubs, including Acer, Alnus, Amelanchier, Aster, Betula, Juglans, Larix, Malus, Prunus, Quercus, Rhus, Ribes, and Salix [e.g., 19].
Therefore, morphometric variability can have a major impact on parasite speciation processes regardless of host speciation by restricting specialists within a particular host and habitat, thereby giving generalists the capability to have a larger host range and/or colonize several habitats.
Bertheau, C., Bankhead-Dronnet, S., Martin, C., Lieutier, F. & Roux-Morabito, G. Lack of genetic differentiation after host range extension argues for the generalist nature of Pityogenes chalcographus (Curculionidae: Scolytinae).
