Data from: Oviposition strategies of Pieridae butterflies in nature and the role of an egg-killing plant trait therein

Most herbivorous insects are host-plant specialists that evolved
detoxification mechanisms to overcome their host plant’s toxins. In the
evolutionary arms-races between Pieridae butterflies and Brassicaceae
plants, some plant species have evolved another defence against the
pierids: egg-killing. Underneath the eggs, leaves develop a so-called
hypersensitive response HR-like cell death. Whether some butterflies have
evolved oviposition strategies to counter-adapt against egg-killing
remains to be studied. In this study, we assessed the oviposition site
location of pierid butterflies on their natural host plants. We described
the plant tissue on which we located the eggs of the most common Pieridae
in the Netherlands: Gonepteryx rhamni, Anthocharis cardamines, Pieris
rapae, P. napi, P. brassicae, and P. mannii. Additionally, we assessed
expression of HR-like cell death in response to the deposited butterfly
eggs. We found that both A. cardamines and G. rhamni mainly oviposited on
the floral stem and the branch, respectively, and oviposited on host
plants from lineages not expected to express HR in response to pierid
eggs. Accordingly, no HR responses were seen. All Pieris eggs found were
located on leaves of their host, the only tissue found to express HR-like
cell death. Furthermore, each Pieris species was found to at least
occasionally oviposit on Brassica nigra. This was the only plant species
in this survey that expressed HR-like cell death in response to the eggs
of P. rapae, P. napi and P. brassicae. Our observations demonstrate that
HR-like cell death remains an effective defence strategy against these
Pieris species and as such did not find evidence for the hypothesised
counterstrategies. Surveying certain key species and disentangling the
micro-evolution of oviposition strategies within a species would allow us
to further  investigate potential counter-adaptations that evolved against
HR-like cell death. This study provides the basis for further
investigation of potential counter-adaptations to egg-killing defences.