Geographic host use variability and host range evolutionary dynamics in the phytophagous insect Apagomerella versicolor (Cerambycidae)

Abstract

The high diversity of phytophagous insects has been explained by the tendency of the group towards specialization; however, generalism may be advantageous in some environments. The cerambycid Apagomerella versicolor exhibits intraspecific geographical variation in host use. In northern Argentina it is highly specialized on the herb Pluchea sagittalis (Asteraceae), while in central and southern areas it uses seven Asteraceae species. To study host species geographical variation from ecological and evolutionary perspectives, we investigated field host availability and use across a wide latitudinal range, and performed laboratory studies on insect oviposition preference and larval performance and mitochondrial DNA (mtDNA) variation in a phylogeographical framework. Geographic variation in host use was unrelated to host availability but was highly associated with laboratory oviposition preference, larval performance, and mtDNA variation. Genetic studies revealed three geographic races of A. versicolor with gene flow restriction and recent geographic expansion. Trophic generalism and oligophagy within A. versicolor seem to have evolved as adaptations to seasonal and spatial unavailability of the preferred host P. sagittalis in cooler areas of the species' geographic range. No single genotype is successful in all environments; specialization may be advantageous in environments with uniform temporal and spatial host availability, while being a trophic generalist may provide an adaptive advantage in host-constrained environments.

2.4. Cerambycidae Latreille, 1802

“…However, the Asclepias cardenolides do suppress the rootfeeding larvae and the advantage of Tetraopes may in fact be its ability to escape competition in a plant inaccessible to other herbivores rather than the acquired protection of adults, which is doubt ful (see above). The supposedly conspe cific allopatric populations of widely distributed species often have more or less different (though usually overlapping) regional host associations; those differences can only be partly explained by the lack of potential hosts in certain regions (e.g., Logarzo et al 2011). More studies, such as that by Michaud & Grant (2005) (who found individuals of Dectes texanus LeConte developing in soybean and sunflower biologically compat ible although strongly differing in average mass), are needed to clarify whether, and at what rate, we may encounter host races or sympatric cryp tic hostspecific species.…”

Local Host Adaptation and Use of a Novel Host in the Seed Beetle Megacerus eulophus

“…We report here two traits, body size and longevity, supporting this hypothesis in the case of the seed beetle Megacerus eulophus . Other studies have not found evidence of host availability influencing local host adaptation in the seed beetle Stator limbatus [7], [8] and in the stem borer Apagomerella versicolor [52].…”

Potential for and consequences of naturalized Bt products: Qualitative dynamics from indirect intransitivities

“…While numerous phytophagous insects are specialists, some pest species have secondary resource plants that can provide some refuge (Logarzo et al, 2011). This would lower the negative effect pest individuals experience due to Bt individuals.…”