Natural breakage of the very long intromittent organ of the seed bug Lygaeus simulans (Heteroptera: Lygaeidae)

The male intromittent organ of the seed bug Lygaeus simulans ends in a long, sclerotized structure which is used to transfer sperm during mating. Observations suggest that this structure becomes brittle and is liable to breakage after being artificially exposed to the air for an extended period of time. In this study we investigate the frequency of intromittent organ breakage in L. simulans. We first examined the intromittent organ of a sample of males that mated once, and found that breakage was rare. We hypothesised that breakages are likely to be more frequent if a male is able to mate multiple times, and so we next paired males with a female for 21 days in order to provide the opportunity for multiple mating. Almost a quarter (22.5%) of these males exhibited signs of genital breakage. The point of breakage varied: for six males only the tip of the structure (around 6% of its length) was missing, whereas for three males over 50% of the structure was missing. However we were unable to locate any fragments of male genitalia in the reproductive tracts of any females that came into contact with these males. This suggests that breakages do not necessarily occur during mating itself, but instead probably occur as the intromittent organ is being retracted into the genital capsule following mating. In this species breakage may not significantly reduce male reproductive fitness as sperm transfer may still be possible.