Thermal sensitivity of the Spiroplasma–Drosophila hydei protective symbiosis: The best of climes, the worst of climes

Abstract

The outcome of natural enemy attack in insects is commonly influenced by the presence of protective symbionts in the host. The degree to which protection functions in natural populations, however, will depend on the robustness of the phenotype and symbiosis to variation in the abiotic environment. We studied the impact of a key environmental parameter—temperature—on the efficacy of the protective effect of the symbiont Spiroplasma on its host Drosophila hydei, against attack by the parasitoid wasp Leptopilina heterotoma. In addition, we investigated the thermal sensitivity of the symbiont's vertical transmission, which may be a key determinant of the ability of the symbiont to persist. We found that vertical transmission was more robust than previously considered, with Spiroplasma being maintained at 25°C, at 18°C and with 18/15°C diurnal cycles, with rates of segregational loss only increasing at 15°C. Protection against wasp attack was ablated before symbiont transmission was lost, with the symbiont failing to rescue the fly host at 18°C. We conclude that the presence of a protective symbiosis in natural populations cannot be simply inferred from the presence of a symbiont whose protective capacity has been tested under narrow controlled conditions. More broadly, we argue that the thermal environment is likely to represent an important determinant of the evolutionary ecology of defensive symbioses in natural environments, potentially driving seasonal, latitudinal and altitudinal variation in symbiont frequency.

Wolbachia -Conferred Antiviral Protection Is Determined by Developmental Temperature

“…Temperature affects many insect-symbiont interactions and their phenotypes ( 1 ), including protective symbiosis ( 65 – 67 ). Therefore, this environmental factor may play a general critical role in determining the outcome of complex host-endosymbiont-pathogen interactions and shape the geographic distribution of insects and their symbionts.…”

The microbiome and mosquito vectorial capacity: rich potential for discovery and translation

“…In mosquitoes, the microbiome, which consists of bacteria, viruses, protozoans and fungi, profoundly alters host phenotypes. Acquisition and the composition of the microbiome are influenced by several abiotic and biotic factors, including host and microbial genetics [1][2][3][4] and the environment [5][6][7]. Therefore, microbiomes of mosquitoes can vary substantially between individuals, life stages, species and over geographical space [8,9], and this variation likely contributes to differences in host phenotypes [10].…”

Rapid divergence in independent aspects of the compatibility phenotype in a Spiroplasma–Drosophila interaction

“…Hy1 falls as an outgroup of S. poulsoni and shows no evidence of reproductive manipulation but enhances host survival following wasp attack [26]. This protective phenotype in the natural host was confirmed in contemporaneous studies in our laboratory [28]. Recipient fly strains, and their status with respect to Wolbachia infection, are detailed in .…”