Egg laying behaviour, host plants and larval survival of Euphydryas aurinia provincialis (Lepidoptera Nymphalidae) in a Mediterranean population (central Italy)

Abstract

In this paper, we show the results of research that can inform conservation measures elsewhere in Europe for the endangered butterfly Euphydryas aurinia. A five year field study was undertaken to identify the host plant preference of larvae of Euphydryas aurinia provincialis in the Mediterranean and which signals are used by females to lay their eggs. The females oviposit on Gentiana cruciata, Scabiosa columbaria and Cephalaria leucantha; the larvae feed on all these plants and additionally on Lonicera caprifoliumin the wild and on Gentiana lutea in the laboratory. The females do not show any preference for a specific host plant and the larvae move from one species of plant to another without any difficulty. The most important factors in determining the female oviposition are the visibility, accessibility and sun-exposure of the host plants. The vegetative state of host plants is the key factor in larval use of plants during the pre- and post-diapause period. The large-sized host plants, G. cruciata and C. leucantha, are optimal for the growth and survival of the pre-diapause I-III larval instar, while they are unavailable to the larvae in Spring because of their delayed vegetative growth. The post-diapause larvae preferentially feed on plants of S. columbaria, and to lesser degree L. caprifolium, as they provide and abundant food source compared with G. cruciata and C. leucantha. The results also suggest that, there is an evolutionary advantage in large numbers of caterpillars feeding together, with the females of E. aurinia provincialis preferring to lay their eggs nearby or above egg batches laid previously by another female, and selecting large plants for oviposition. Despite the competition for food among caterpillars, the oviposition behaviour of females is advantageous and increases the larval survival rate on large plants. The gregarious larval behaviour provides several benefits during both pre-diapause period (avoiding starvation) and post-diapause period (efficiency in thermoregulation).

Make it simple: mating behaviour ofEuphydryas aurinia provincialis(Lepidoptera: Nymphalidae)

“…Our field-work was carried out on a population of E. a. provincialis discovered during a previous work on Lepidoptera around Vallemare (RI, Lazio) (Pinzari et al 2010). Here, the species occupies montane grasslands and sometimes steep and rocky slopes, within a mosaic of different habitats including wooded areas, hedgerows, fields and less steep areas occasionally ploughed and cultivated (Pinzari et al 2016).…”

“…In previous studies, we provided important information for the conservation of the populations living in Central Italy, where this species is in a better state than elsewhere. For several years we studied a population of E. a. provincialis (Boisduval, 1828) focusing on several aspects of the species biology and in particular on larval host plants preference (Pinzari et al 2016), predators (Pinzari 2016) and parasitoids (Pinzari et al 2017), adult population dynamics and, finally, on courtship and mating behaviour.…”

Notes on Life-History of Erycia Furibunda (Diptera Tachinidae), a Parasitoid of Euphydryas Aurinia Provincialis (Lepidoptera Nymphalidae)

“…The fourth instar larvae are still gregarious although not inside a silk nest; the fifth and sixth instar larvae are solitary. The pupal stage occurs in April and the adult emergence starts in May (PINZARI et al, 2016).…”

“…connected by adult dispersal (HULA et al, 2004); in addition, the species varies geographically in host plant use (see revisions in SINGER, 2003SINGER, , 2004PINZARI et al, 2016). However, relatively less emphasis has addressed to the role of parasitoids.…”

“…provincialis was recorded in the past (Umbria, FORD et al, 2000). Moreover, during our previous field-work on larval stages of E. a. provincialis in Central Apennines (PINZARI et al, 2016) we recorded the tachinid Erycia furibunda on larval nests of the butterfly.…”