Narrow oviposition preference of an insect herbivore risks survival under conditions of severe drought

Abstract

<jats:title>ABSTRACT</jats:title><jats:p><jats:list list-type="order"><jats:list-item><jats:p>Understanding species’ habitat preferences are crucial to predict organisms’ responses to the current climate crisis. In many insects, maternal habitat selection for oviposition essentially determines offspring performance. Whether changes in climatic conditions may pose future mismatches in oviposition preference and offspring performance when mothers continue to prefer microhabitats that now threaten offspring survival is an open question.</jats:p></jats:list-item><jats:list-item><jats:p>To address this, we tested if oviposition preferences put offspring at risk in the Glanville fritillary butterfly (<jats:italic>Melitaea cinxia</jats:italic>) under drought stress. Mainly, we focus on identifying the microhabitat determinants for oviposition and the variation of conditions experienced by the sessile offspring, using field observations from 12 populations collected over 2015-2018. These data are combined with ten years of larval nest and precipitation data to understand within-population patterns of habitat selection. We tested whether the preferred microhabitats maximized the extended larval performance (i.e. overwinter survival).</jats:p></jats:list-item><jats:list-item><jats:p>We found that females preferentially oviposited in microhabitats with higher host plant abundance and higher proportion of host plants with signs of drought stress. In most years, larval nests had higher survival in these drought-stressed microhabitats. However, in an extremely dry year, only two nests survived over the summer.</jats:p></jats:list-item><jats:list-item><jats:p>Our results highlight that a failure to shift habitat preference under extreme climate conditions may have drastic consequences for the survival of natural populations under changing climatic conditions.</jats:p></jats:list-item></jats:list></jats:p>

The effect of summer drought on the predictability of local extinctions in a butterfly metapopulation

“…These data suggest that the severe drought negatively affected the quality and availability of the host plants of these herbivorous insects, making resources scarce when demands were high. These results are in line with detailed observations made in 12 focal patches in 2018, where despite observing large numbers of clutches in early summer, only 2 larval nests were found in autumn (Salgado et al 2020). The host plants are known to recover quickly from drought, and the proportion of desiccated host plants in the habitat, as assessed during the survey in autumn, is a poor predictor of plant condition during larval development (Tack et al 2015).…”

Metabarcoding reveals massive species diversity of Diptera in a subtropical ecosystem

“…Our study suggests that turnover of Diptera communities is strongly structured by three abiotic factors, aspect, season, and elevation. Significantly higher species richness and diversity per sampling plot were observed on the north‐facing compared to the south‐facing slope, presumably related to variation in sun exposure that influence environmental variables differently by altering the light, temperature, humidity, and food resources of the habitat (Bartlett et al, 2020; Giersch et al, 2017; Jeffries et al, 2006; Salgado et al, 2020; Weiss et al, 2013). In this study area of subtropical secondary broadleaf forest, the south‐facing slope receives more solar radiation and has closed canopy cover with a moist forest floor, while the north‐facing slope is often shaded, with a relatively open canopy and dry forest floor.…”

Multidimensional plasticity in the Glanville fritillary butterfly: larval performance curves are temperature, host and family specific

“…Alternatively, when immature life-stages are largely immobile, such as in the case of the Glanville fritillary butterfly, the optimal thermal environment for development can be realized through selective oviposition choices of the female. As is true for many butterfly species, Glanville fritillary mothers could regulate the thermal environment of their offspring by preferring sunny or shady environments for oviposition [28, 29]. Averaged over the families, our data showed a clear initial increase in growth rate with increasing temperature, with an optimum around 32 °C.…”

“…Adult females produce large egg clutches, and the selection of suitable oviposition sites is known to be a hierarchical process [26, 27]. In the field, gravid females of the Glanville fritillary appear to first choose habitats that are hot, dry and sunny [28, 29]. Host plant discrimination, with individuals typically preferring one host species over the other, occurs subsequently [30, 31].…”