Oviposition Substrate of the Mountain Fly Drosophila nigrosparsa (Diptera: Drosophilidae)

Abstract

The survival of insect larvae often depends on the mother’s choice of oviposition substrate, and thus, this choice is an essential part of an insect species’ ecology. Especially species with narrow substrate preferences may suffer from changes in substrate availability triggered by, for example, climate change. Recent climate warming is affecting species directly (e.g., physiology) but also indirectly (e.g., biological interactions) leading to mismatching phenologies and distributions. However, the preferred oviposition substrate is still unknown for many drosophilid species, especially for those at higher elevations. In this study, we investigated the oviposition-substrate preference of the montane-alpine fly Drosophila nigrosparsa in rearing and multiple-choice experiments using natural substrates in the laboratory. Insect emergence from field-collected substrates was tested. More than 650 insects were reared from natural substrates, among them 152 drosophilids but no individual of D. nigrosparsa. In the multiple-choice experiments, D. nigrosparsa preferred ovipositing on mushrooms (> 93% of eggs); additionally, a few eggs were laid on berries but none on other substrates such as cow faeces, rotten plant material, and soil. The flies laid 24 times more eggs per day when mushrooms were included in the substrates than when they were excluded. We infer that D. nigrosparsa is a mushroom breeder with some variation in oviposition choice. The flies favoured some mushrooms over others, but they were not specialised on a single fungal taxon. Although it is unclear if and how climate change will affect D. nigrosparsa, our results indicate that this species will not be threatened by oviposition-substrate limitations in the near future because of the broad altitudinal distribution of the mushrooms considered here, even if the flies will have to shift upwards to withstand increasing temperatures.

Wolbachia affect behavior and possibly reproductive compatibility but not thermoresistance, fecundity, and morphology in a novel transinfected host, Drosophila nigrosparsa

“…Drosophila nigrosparsa is a species restricted to montane and alpine areas in Central and Western Europe with its main distribution around 2,000 m above sea level (Bächli & Burla, 1985; Bächli, Vilela, Escher, & Saura, 2004). Under simulated conditions of alpine summer, these flies have around 60 days of development time from embryos to adults (Kinzner et al, 2016). Several life history traits and physiological limits of D. nigrosparsa have been studied before (Kinzner et al, 2016, 2018; Tratter Kinzner et al, 2019).…”

“…Under simulated conditions of alpine summer, these flies have around 60 days of development time from embryos to adults (Kinzner et al, 2016). Several life history traits and physiological limits of D. nigrosparsa have been studied before (Kinzner et al, 2016, 2018; Tratter Kinzner et al, 2019). Drosophila nigrosparsa is less fecund and relatively long living compared with other Drosophila species, and it is well adapted to current cold and hot temperatures (Kinzner et al, 2018).…”

Chemosensory adaptations of the mountain fly Drosophila nigrosparsa (Insecta: Diptera) through genomics’ and structural biology’s lenses

“…These changes could affect the ion channel formation and functioning once the heterodimer is formed 6 . Drosophila nigrosparsa is a mushroom breeder (with more than 93% of eggs deposited on them in experiments) but not specialised on a single fungal taxon 23 . Modifications in DnigOr56a receptor may thus possibly reflect important adaptation towards different types of toxic compounds possibly present in fungi, and their recognition in non-suitable fungi species might inhibit positive chemotaxis, avoiding the oviposition 40 .…”

“…Among the distinctive ecological niches occupied by the multitude of Drosophila species, D. nigrosparsa is a habitat specialist, restricted to the European montane/alpine zone with a maximum density at about 2000 m above sea level, and most abundant at the timber line 22 . Its life history starts being revealed, and its preferred oviposition substrate are fungi 23 . Given the harsh conditions of the habitat, the fly likely evolved particular adaptations to inhabit the alpine ecosystem.…”

Differential gene expression inDrosophila melanogasterandD. nigrosparsainfected with the sameWolbachiastrain

“…Drosophila (Drosophila) nigrosparsa is an alpine species found at around 2000 m above sea level in Central and Western Europe (Bächli et al ., 2004). Due to the habitat specificity of D. nigrosparsa , molecular and physiological traits and potential effects of warming temperatures on this species have been studied (Arthofer et al ., 2015; Kinzner et al ., 2016, 2018, 2019; Cicconardi et al ., 2017; Tratter Kinzner et al ., 2019). Wild populations of D. melanogaster are commonly infected with Wolbachia (Verspoor and Haddrill, 2011), while no wild population of D. nigrosparsa infected with Wolbachia has been found to date (M. Detcharoen, unpubl.).…”