Reproductive barriers between the partially sympatric Colorado and false potato beetles

The partially sympatric Colorado potato beetle (CPB), Leptinotarsa decemlin eata (Say), and the false potato beetle (FPB), Leptinotarsa juncta (Germar) , were shown to possess a series of reproductive barriers that protect spec ies integrity. A strongly stereotyped sequence of courtship behaviour insur es that more than 85% of encounters between these congeneric species are te rminated before copulation. The courtship behaviour of the FPB, described h ere for the first time, is similar to that for the CPB. However, the male F PB is more Likely to walk off the female FPB and will repeat antennal tappi ng more frequently than the CPB before moving on to palp tapping and mating . Observations suggest that both species first use antennal tapping for an initial olfactory assessment of the object as a female insect of a given fa mily or species and palp tapping for final sex recognition. If courtship be haviour fails to break up the hybridization pairs, there is no mechanical b arrier to mating and sperm transfer takes place. However, there is gametic mortality. The FPB is more fecund than the CPB and seems less dependent tha n the CPB on multiple matings to reach its full reproductive potential.