Investigating the role of sexual conflict in parasitoid- host eco-evolutionary dynamics

Finding ways to grow enough food to sustain the ever-growing human population while
minimising detrimental impacts on the natural environment is a pressing global challenge
[1,2]. Current food production systems rely heavily on the use of agro-chemicals for pest
control, the negative impacts of which are extreme for species, ecosystems and for
climate change [3-7]. Integrated pest management (IPM) is one strategy that will be
critical if we are to feed the human population without inflicting irreversible environmental
damage. IPM prioritizes biodiversity-based pest control and considers the use of chemical
pesticides only as a last resort [8].
Parasitoid wasps are a large group of insects, which are commonly used as a chemical-free means of controlling insect pests (biological control). Adults are free-living, females
lay their eggs on or in other species and their offspring feed on this host, typically another
insect, invariably killing it. In addition to their economic value, parasitoid wasps have long
been used by blue skies researchers to understand fundamental questions about
evolution, ecology and physiology [9,10]. This research has supported their use in crop
protection and assisted biocontrol practitioners in selecting the most appropriate species
to control a given pest [9,10].
Despite the abundance of studies on parasitoid behavioural ecology, these species have
received little attention in studies of sexual selection and sexual conflict [11]. Sexual
conflict occurs when the optimum strategy or trait is different for males and females [12].
For instance, the optimal mating rate is generally higher for males than females. This can
result in reduced fitness for females if accepting or resisting superfluous male copulation
attempts is costly [12, 13]. If these costs manifest as reduced offspring production, there
can be consequences for recruitment and even population viability [13]
For parasitoid wasps in natural and agricultural settings, sexual conflict may have
profound consequences for parasitism rates. Understanding the extent to which sexual
conflict influences individual and population fitness in these insects provides new and
valuable information on how aspects of these species' mating systems can influence
host-parasitoid dynamics and coevolution as well as the efficacy of pest control under
different IPM scenarios.