Yoshida Mizuki, Convey Peter, Hayward Scott A L, Lee Richard E, Denlinger David L, Teets Nicholas M, Goto Shin G
Graduate School of Science, Osaka City University, Osaka, Japan.
Department of Entomology, Ohio State University, Columbus, OH, USA.
Sci Rep. 2025 Feb 12;15(1):3890. doi: 10.1038/s41598-025-86617-4.
The Antarctic midge, Belgica antarctica, is a unique insect endemic to Antarctica. It has a 2-year life cycle, with larvae overwintering in two different instars and adults emerging the following summer. This seasonality is crucial for adaptation to Antarctica's harsh climates and ephemeral growing seasons; however, the underlying mechanisms remain unclear. We found that, under summer-like conditions, larvae could develop from egg to the fourth-instar larval stage without interruption, but they never pupated. Spontaneous developmental arrest at this stage suggests that they overwinter in obligate diapause, a genetically determined period of dormancy. The winter cold can terminate this diapause, and long-term cold exposure is more effective. Although this species can utilise two alternative cold tolerance strategies with diapause for overwintering, freezing was more successful than cryoprotective dehydration in allowing survival and developmental resumption in our experimental conditions. In contrast, the first three larval instars continued their development under the same conditions as the fourth-instar larvae. Although we do not exclude the possibility of facultative diapause, they likely overwinter in a quiescent state, an immediate developmental arrest in response to adversity, to maximise exploitation of the short Antarctic summer. Diapause and quiescence ensure developmental and reproductive success in this extremophile insect.
南极蠓（Belgica antarctica）是南极洲特有的一种独特昆虫。它有一个两年的生命周期，幼虫在两个不同的龄期越冬，成虫在次年夏天出现。这种季节性对于适应南极洲恶劣的气候和短暂的生长季节至关重要；然而，其潜在机制仍不清楚。我们发现，在类似夏季的条件下，幼虫可以从卵不间断地发育到四龄幼虫阶段，但它们从不化蛹。在这个阶段的自发发育停滞表明它们以专性滞育越冬，这是一个由基因决定的休眠期。冬季的寒冷可以终止这种滞育，长期暴露在寒冷中更有效。虽然该物种可以利用两种替代的耐寒策略通过滞育越冬，但在我们的实验条件下，冷冻比抗冻脱水在允许存活和恢复发育方面更成功。相比之下，前三龄幼虫在与四龄幼虫相同的条件下继续发育。虽然我们不排除兼性滞育的可能性，但它们可能以静止状态越冬，即对逆境的立即发育停滞，以最大限度地利用南极短暂的夏季。滞育和静止确保了这种极端嗜热昆虫的发育和繁殖成功。
