Cannibalism and potential predation in larval drosophilids

Abstract

1. Although yeast encompasses the major food source of Drosophila melanogaster, a recent study demonstrated that D. melanogaster larvae can complete their development on an exclusively cannibalistic diet. If cannibalism is an adaptive behaviour under nutritional stress, not only conspecific larvae but also allospecific larvae could be the target of predation. Under natural conditions, stings of parasitoids can cause a larval injury that attracts cannibalistic larvae, however, the effect of parasitism on larval cannibalism has never been investigated in drosophillids. 2. Here, we investigated the cannibalistic and predatory behaviour of four frugivorous Drosophila species (Drosophila simulans, D. melanogaster, Drosophila auraria, Drosophila triauraria) towards the conspecific or allospecific source of attraction (SOA) larvae. We also investigated their attraction to parasitised conspecific SOA larvae. 3. The present study demonstrates that the cannibalism observed previously could be potentially extended to predation in D. simulans and D. melanogaster, leading to intra‐guild predation that has not been previously observed. Although D. auraria and D. triauraria were not significantly attracted to conspecific SOA, some level of attraction was suggested for allospecific SOA. In agreement with this, larvae of these species did not complete their development to adulthood when reared on an exclusively cannibalistic diet. The injury inflicted by parasitoid wasps was shown to attract cannibals in some cases. 4. The current results indicate that cannibalistic behaviour might not be a general feature in drosophilids. The environmental conditions or selective pressure that drives the evolution of cannibalism within this group should be a target of future studies.

Density-by-Diet Interactions during Larval Development Shape Adult Life History Trait Expression and Fitness in a Polyphagous Fly

“…Surprisingly though, we found that while lipid reserve was negatively associated with larval density in protein-rich and standard diet (as expected), lipid reserves increased with larval density in sugar-rich diets. The mechanisms underpinning this effect is unclear and there is no evidence of larval cannibalism [as in Drosophila species (Vijendravarma et al 2013;Kakeya and Takahashi 2020)], but it is possible that protein limitation and high intraspecific competition combined triggered stress responses that resulted in individuals having lower body weight but higher lipid storage. In mice, stress is known to stimulate lipid synthesis but deactivate protein synthesis (Fu et al 2011)].…”

Relatedness modulates density‐dependent cannibalism rates in Drosophila

“…Although it is impossible to dismiss the potential for a lab environment to select for cannibalistic individuals, cannibalism has been observed repeatedly across Drosophila spp. (Bhattacharyya, 2015; Kakeya & Takahashi, 2021; Vijendravarma et al, 2013). Also, several of these observations were of individuals that had been collected from the wild only weeks before experimentation (Bhattacharyya, 2015).…”

“…For the relatedness trials, a third‐instar victim from the WT and GFP families was selected from their respective ‘early’ vials and each was secured by being impaled on equally sized entomological pins at either end of a 55‐mm diameter Petri dish (15 mm from the centreline) containing agar. Previous work has shown that cannibals are preferentially attracted to injured over non‐injured victims (Kakeya & Takahashi, 2021; Vijendravarma et al., 2013); thus, pinning the larvae likely sped up the onset of cannibalism. Also, pinning the victims in this way ensured that they remained equidistant from the centre of the dish.…”

Behaviour of two fly species reared for livestock feed: optimising production and insect welfare

“…In D. melanogaster cannibalism occurs in crowded conditions, where young larvae will attack and consume pre-pupation larvae which are in the 'wandering-stage' (Vijendravarma et al, 2013). Larvae of D. melanogaster and Drosophila simulans Sturtevant (Diptera: Drosophilidae) form aggregations mediated by chemical cues from the injured prey larvae (Kakeya and Takahashi, 2021). The larvae of D. melanogaster and D. simulans are able to sustain themselves, develop normally and reach adulthood on a solely cannibalistic diet, unlike other Drosophila species (Kakeya and Takahashi, 2021;Vijendravarma et al, 2013).…”

“…Larvae of D. melanogaster and Drosophila simulans Sturtevant (Diptera: Drosophilidae) form aggregations mediated by chemical cues from the injured prey larvae (Kakeya and Takahashi, 2021). The larvae of D. melanogaster and D. simulans are able to sustain themselves, develop normally and reach adulthood on a solely cannibalistic diet, unlike other Drosophila species (Kakeya and Takahashi, 2021;Vijendravarma et al, 2013). Therefore, cannibalistic behaviour is likely not a general feature of the whole Drosophila genus.…”