Association of insect life stages using DNA sequences: the larvae of Philodytes umbrinus (Motschulsky) (Coleoptera: Dytiscidae)

Abstract

Insect life stages are known imperfectly in many cases, and classifications are based often on only one or a few semaphoronts of a species. This is unfortunate as information in alternative life stages often is useful for scientific study. Although recent examples of DNA in taxonomy have emphasized the identification of indistinguishable species, such sequence data facilitate the association of life history stages and hold considerable promise in phylogenetic analysis, evolutionary studies, diagnostics, etc. These concepts are discussed here and an example is provided from diving beetles (Dytiscidae: Coleoptera). Three unknown larval specimens of an apparent species of Laccophilinae collected in Namibia were associated with the species Philodytes umbrinus (Motschulsky) using DNA sequence data. An 806-bp portion of the gene cytochrome oxidase I was sequenced from the unknown larvae. Several identified adult specimens of species of Laccophilinae from Namibia were also sequenced, including two P. umbrinus specimens and specimens from four Laccophilus Leach species. Additional species of Laccophilus from other areas of the world also were sequenced, as were specimens of Agabetes acuductus (Harris), Australphilus saltus Watts, Neptosternus boukali Hendrich & Balke and a species of Laccodytes Re´gimbart. Parsimony analysis resulted in two most parsimonious trees with the unknown larva unambiguously resolved in a group with both adult specimens of P. umbrinus (bootstrap value ¼ 100%). The average pairwise p-distance between the unknown larva and adult P. umbrinus specimens averaged 0.09% (0-0.14%), compared with an average divergence between other conspecifics in the analysis of 0.24% (0-0.82%) and an overall average divergence between species of 13.49% (1.90-19.86%). Based on this, the unknown larvae were assigned to P. umbrinus. The larvae are diagnosed and described and their relationship with other Laccophilinae is discussed.

Association of nymphs and adults of Ephemeroptera (Insecta) using the amplified fragment length polymorphism (AFLP) technique

“…1), and every terminal branch at the species level was supported 100% by bootstrap analysis, regardless of the location where they were collected. This result was in agreement with the association between larva and adult stages in other insects, when gene sequences were used (Miller et al, 2005(Miller et al, , 2007Fleck et al, 2006;Jeon and Ahn, 2007). In this research, the AFLP technique revealed advantages in relation to other molecular techniques; for instance, previous knowledge about the gene sequence of the organisms studied was not necessary and allowed exploration and comparison of the whole genome, despite its moderate cost (Ferna´ndez-Cuenca, 2004;Meudt and Clarke, 2007).…”

“…In this research, the AFLP technique revealed advantages in relation to other molecular techniques; for instance, previous knowledge about the gene sequence of the organisms studied was not necessary and allowed exploration and comparison of the whole genome, despite its moderate cost (Ferna´ndez-Cuenca, 2004;Meudt and Clarke, 2007). In contrast, the association using sequences required more expensive molecular strategies in order to obtain previous knowledge about the entire extent of variation in the target gene (Miller et al, 2005).…”

“…A complete knowledge of the life stages of species provides important information for the progress of ecological, phylogenetic and evolutionary studies (Miller et al, 2005;Jeon and Ahn, 2007). There are currently different molecular biology techniques that have used DNA as a taxonomic character in the association of immature and adult stages of insects (Miller et al, 2005(Miller et al, , 2007Fleck et al, 2006;Jeon and Ahn, 2007).…”

“…There are currently different molecular biology techniques that have used DNA as a taxonomic character in the association of immature and adult stages of insects (Miller et al, 2005(Miller et al, , 2007Fleck et al, 2006;Jeon and Ahn, 2007). For example, Miller et al (2005) developed strategies for the association of unknown larvae and known adults of Dytiscidae (Coleoptera) using DNA sequence data, with an 806-bp portion of the gene cytochrome oxidase I. In 2007, Jeon and Ahn used the partial cytochrome oxidase II gene (375 bp) to associate unknown larvae and identified adults of the Staphilinidae (Coleoptera).…”

DNA barcoding demystified

“…The identification of insect larvae (the stage that most often damages crops) is often problematic, but DNA barcodes can be used to match larvae with identified adults (Miller et al 2005;Caterino & Tishechkin 2006;Rojo et al 2006;Ahrens et al 2007). This can have immediate practical application in taxonomy, resource management and biosecurity.…”