Elytra colour polymorphism and randomness of matings in Chauliognathus fallax Germar 1824 from southern Brazil (Coleoptera, Cantharidae)

Abstract

ABSTRACT. Beetles of the species Chauliognathus fallax Germar 1824 are polymorphic for elytron colouration with six morphs distinguished on the basis of black pigmentation on a yellow background. We investigated samples of C. fallax taken in eight consecutive weeks aiming to determine the frequency of the morphs which were grouped, for statistical analysis, into three classes according to elytra pigmentation as well as the possible occurrence of assortative mating. Our results showed a variation in the frequency of the classes throughout the season, both in males and females, with the maximum frequency of each class at the fourth and fifth week. The three classes (A, B, C) showed the same pattern of variation, and class B was always the more frequent. To test randomness of matings two approaches were taken: in the first, we compared the frequency of each class in copulating and non-copulating insects. In the second, the frequency of each class in the whole sample was taken as the probability of occurrence of the respective class; then, using the criterion of the probability of independent events we calculated the expected proportion of copulating insects for each pair of events. Both methods gave non-significant differences, suggesting that the matings were random.

Identification and Synthesis of the Male-Produced Sex Pheromone of the Soldier BeetleChauliognathus fallax(Coleoptera: Cantharidae)

“…6 However, the explanation for the maintenance of the polymorphism is still unclear and could be caused by assortative mating, natural selection or other natural processes. 7 The study of chemical ecology as well as other ecological aspects of this species could help on the discovery and development of an environmentally friendly approach to the control of chrysomelid beetles.…”

Analysis of the geographical variation of elytral color polymorphisms in three species of soldier beetles, Chauliognathus Hentz (Cantharidae) in southern Brazil

“…This would suggest that the persistence of the coloration patterns may be due to abiotic factors such as temperature, pressure and humidity but in the present state of our knowledge, we cannot be certain. However, MACHADO & ARAÚJO (1999, 2003 did not find any indication of preferential crossings in C. flavipes e C. fallax capable of explaining the color polymorphism.…”

Ecology and behavior of Pachycoris torridus (Hemiptera: Scutelleridae): new host plant, color polymorphism, maternal care and parasitism

“…Paleari (1992Paleari ( , 1994 detected different diapause length, parasite preference, offspring production, and even survival among the different phenotypes of the scutellerid Agonosoma flavolineatum. Besides, color polymorphism may influence patterns of communication between sexes and, hence, mating probability within different phenotypes (Machado & Araújo, 2003).…”