Oviposition-site preferences of a declining butterfly Erebia medusa (Lepidoptera: Satyrinae) in nutrient-poor grasslands

Abstract

Abstract. Butterflies belong to one of the most intensively studied invertebrate groups. However, detailed information on the larval ecology is still lacking in many species. This is especially true for the grass-feeding subfamily Satyrinae, to which our study species, the Woodland ringlet (Erebia medusa Fabricius, 1787), belongs. At the habitat level, E. medusa exhibits a clear preference for abandoned grasslands with litter accumulation. In this study, we assessed the host-plant and oviposition preferences of E. medusa at the microhabitat level, i.e., within occupied habitat patches, in the Diemel Valley (Central Germany). Only two species of grass, Festuca ovina agg. and F. rubra agg., were systematically used for oviposition. Egg density was positively correlated with patchiness of herb layer, potential daily length of sunshine, and abandonment. However, the explanatory power of these parameters was low. We attribute this primarily to an ample supply of host plants growing under suitable conditions in the occupied habitat patches of E. medusa. The positive effect of abandonment is probably due to the fact that the average height of oviposition sites of E. medusa is greater than in most other satyrine species, which renders the eggs more vulnerable to mechanical disturbance. Moreover, thick layers of litter, which develop after the cessation of grazing or mowing, might be important as they modify the microclimate at the locations of the immature stages.

Vegetation composition and structure are important predictors of oviposition site selection in an alpine butterfly, the Mountain Ringlet Erebia epiphron

“…Oviposition on and selection for sites with abundant cover of Nardus stricta is documented (Boyd-Wallis 1994) and is consistent with the long-held view that this grass is a key larval food plant for Mountain Ringlets in Britain (Asher et al 2001). Selection of Festuca ovina for egg-laying, in contrast, is a relatively novel finding for the species in Britain, having only been indicated by one prior small-scale study of Mountain Ringlets in the Lake District (Shannon 1995), although we note that F. ovina and related fescues are important host plants of other Mountain Ringlet subspecies and congeneric Erebia species in continental Europe (Kuras et al 2001, Stuhldreher andFartmann 2015). The preference for egg sites dominated by Nardus stricta and Festuca ovina was a consistent feature across all studied Mountain Ringlet colonies (see Fig.…”

“…Other vegetation characteristics associated with egg site selection of Mountain Ringlets were vegetation height and density, and the cover of tussocks. Sites selected for egg-laying had shorter and sparser vegetation (also see Stuhldreher and Fartmann 2015). Short, sparse grass swards permit ovipositioning females easy access to the surface layer to deposit their eggs on suitable low-growing hostplants, and they also ensure a warm microclimate by minimising the potential shading effects of taller vegetation (e.g.…”

New approach for butterfly conservation through local field‐based vegetational and entomological data

“…Herbage removal by ruminants and mowing has a strong effect on vegetation structure and composition (Kohler et al, 2004), and it was assumed that a high presence of litter is an indicator of low recent grazing intensity or mowing frequency. Litter abundance has already been seen as a possible factor influencing butterfly oviposition (Ewing et al, 2020; Stuhldreher & Fartmann, 2015), highlighting its microclimate function that reduces extreme temperature fluctuations. Here, we used litter for its additional indicator of management intensity, suggesting that butterfly presence was favored by a low management intensity (corresponding to a high presence of litter; Orlandi et al, 2016), probably related to occasional mowing or low‐intensity grazing.…”

Not Too Warm, Not Too Cold: Thermal Treatments to Slightly Warmer or Colder Conditions from Mother’s Origin Can Enhance Performance of Montane Butterfly Larvae

“…In Lepidoptera, the larvae, especially during the early immature stages (egg, larva, pupa), have limited or zero mobility [ 14 ] and may be unable to move to alternate habitats. Hence, the mother’s oviposition locations determine the conditions that the offspring will experience, and these consequently influence larval development and survival [ 15 , 16 ].…”