Reproductive Strategies in Paternal Care and Remarkably Low Paternity Level in a Giant Water Bug

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Reproductive strategies

Background:

• Parental care is a key reproductive strategy influencing organism fitness.
• Paternal care, where males solely care for offspring, is rare, especially in invertebrates, due to high reproductive costs.
• The evolution and maintenance of paternal care in males remain poorly understood.

Purpose of the Study:

• To investigate the evolution and maintenance of paternal care in the giant water bug, *Appasus japonicus*.
• To assess actual paternity rates in a species known for paternal care.
• To challenge established theories on insect reproductive strategies.

Main Methods:

• Laboratory mating trials with *Appasus japonicus*.
• Development and application of sensitive molecular markers for paternity testing.
• Analysis of mating behaviors and offspring care patterns.

Main Results:

• Unexpectedly low actual paternity rates were observed in males providing care.
• Most males cared for eggs sired by other males, with evidence of cuckoldry.
• Paternity rates in belostomatid insects were previously thought to be high, contrary to these findings.

Conclusions:

• The study overturns the established theory of paternal care evolution in insects.
• Findings suggest complex reproductive strategies and potential costs associated with paternal care in giant water bugs.
• Further research is needed to fully understand the evolutionary dynamics of paternal care in this species.