Phenological matching rather than genetic variation in host preference underlies geographical variation in host plants used by orange tip butterflies

Abstract

An insect species that shows variation in host species association across its geographical range may do so either because of local adaptation in host plant preference of the insect or through environmentally or genetically induced differences in the plants, causing variation in host plant suitability between regions. In the present study, we experimentally investigate the host plant preference of Anthocharis cardamines (orange tip butterfly) in two populations from the UK and two from Sweden. Previous reports indicate that A. cardamines larvae are found on different host plant species in different regions of the UK, and some variation has been reported in Sweden. Host plant choice trials showed that females prefer to oviposit on plants in an earlier phenological stage, as well as on larger plants. When controlling for plant phenological stage and size, the host species had no statistically significant effect on the choice of the females. Moreover, there were no differences in host plant species preference among the four butterfly populations. Based on our experiment, the oviposition choice by A. cardamines mainly depends on the phenological stage and the size of the host plant. This finding supports the idea that the geographical patterns of host-plant association of A. cardamines in the UK and Sweden are consequences of the phenology and availability of the local hosts, rather than regional genetic differences in the host species preference of the butterfly.

Multiple temperature effects on phenology and body size in wild butterflies predict a complex response to climate change

“…Anthocharis cardamines is a phenological specialist, in the sense that oviposition is restricted to host plants at a specific phenological stage (St alhandske et al 2016); polyphagy may have evolved in this species partly to alleviate the risks associated with this strategy (Wiklund and Friberg 2009). Anthocharis cardamines is a phenological specialist, in the sense that oviposition is restricted to host plants at a specific phenological stage (St alhandske et al 2016); polyphagy may have evolved in this species partly to alleviate the risks associated with this strategy (Wiklund and Friberg 2009).…”

“…Larvae develop in late spring/ early summer on the seed pods of their hosts, and can be regarded as phenological specialists (St alhandske et al 2016). The emergence period begins in April or May (more recently in late March) and lasts for about 6 weeks.…”

“…These effects may lead to complex feedbacks and interactions at the individual, population, and community levels, rendering their long-term impact on species abundance within ecosystems challenging to predict. In phytophagous insects, phenological mismatching will be particularly dangerous when host specialization (monophagy/oligophagy) is accompanied by phenological specialization (St alhandske et al 2016), in which larvae are adapted to a specific stage in the life-history of their hosts, for example, bud burst (Singer and Parmesan 2010) or seed-pod production (St alhandske et al 2016). Within communities, unequal phenological shifts between trophic levels can disrupt both mutualistic and antagonistic interactions (Rafferty et al 2015(Rafferty et al , K} or€ osi et al 2018.…”

Variation in adult stress resistance does not explain vulnerability to climate change in copper butterflies

“…Epigenetic processes are fast and may be important under changing environmental conditions (Bossdorf et al, 2008;Johannes et al, 2009;Nicotra et al, 2010;Franks & Hoffmann, 2012). Finally, while we here exclusively looked at direct effects of temperature, indirect effects may be equally important through changes in host-plant quality (Bauerfeind & Fischer, 2013) or phenology (e.g., Navarro-Cano et al, 2015;Stålhandske et al, 2016).…”

Host plant phenology, insect outbreaks and herbivore communities – The importance of timing

“…Phenological variation has proven important in determining larval growth rate (Schwartzberg et al, 2014), insect fitness (Tikkanen & Julkunen-Tiitto, 2003) and the structure of insect communities (Crawley & Akhteruzzaman, 1988;Sinclair et al, 2015). Since plant and insect phenology are sensitive to temperature (Parmesan, 2007;Thackeray et al, 2016), an asymmetrical response to temperature at different trophic levels (Thackeray et al, 2016) could lead to a shift in interaction strength, resulting in a weakened (Burkle, Marlin, & Knight, 2013;Kharouba et al, 2018;Stalhandske et al, 2016) or a strengthened interaction (Kharouba et al, 2018;Schwartzberg et al, 2014).…”