Distribution of constitutive heterochromatin in Pachycoris torridus (Hemiptera, Scutelleridae) with different chromatic patterns.

The stink bug Pachycoris torridus is a pest of great agricultural importance due to its records on culture of physic nut (Jatropha curcas), which is the raw material for biodiesel production. An interesting feature of this insect is its high phenotypic variability, a characteristic that resulted in it being classified as a new species on eight separate occasions. In the suborder Heteroptera, the heterochromatin pattern is specific and often allows species to be differentiated. To confirm whether there is differentiation between specimens of P. torridus with different color patterns (yellow, orange, brown, and red), samples were analyzed cytogenetically using the C-banding method. During meiotic prophase, the four color patterns analyzed showed a large heterochromatic chromocenter, consisting of a combination of both sex chromosomes (X and Y). Thus, the present study reports chromosomal homogeneity in different color patterns of P. torridus and highlights the importance of this tool in the description of new species.

High genetic variability and polychromatism in Pachycoris torridus (Heteroptera: Scutelleridae).

The stink bug Pachycoris torridus is listed among the most polyphagous insects in the world and it is a major pest of diverse crops, in particular the physic nut Jatropha curcas, which is used as a raw material for biodiesel production. A peculiar characteristic of this species is its high phenotypic variability, a characteristic that makes identification difficult: P. torridus has been described as a new species eight times. Thus, to aid in identification, genetic characterization of this insect was performed. We verified that, due to the high genetic variability of P. torridus, several genetic patterns exist that result in the same phenotype.