Data from: Phenotypic variation in overwinter environmental transmission of a baculovirus and the cost of virulence

A pathogen's ability to persist in the environment is an ecologically important trait, and variation in this trait may promote coexistence of different pathogen strains. We asked whether naturally occurring isolates of the baculovirus that infects gypsy moth larvae varied in their overwinter environmental transmission, and whether this variation was consistent with a tradeoff or an upper limit to virulence that might promote pathogen diversity. We used experimental manipulations to replicate the natural overwinter infection process using 16 field-collected isolates. Virus isolates varied substantially in the fraction of larvae infected, leading to differences in overwinter transmission rates. Furthermore, isolates that killed more larvae also had higher rates of early larval death in which no infectious particles were produced, consistent with a cost of high virulence. Our results thus support the existence of a cost that could impose an upper limit to virulence even in a highly virulent pathogen.

病原体在环境中的持续存活能力是一项具有重要生态学意义的性状，该性状的变异或可推动不同病原体菌株的共存。我们旨在探究感染舞毒蛾（gypsy moth）幼虫的杆状病毒（baculovirus）天然分离株，其越冬环境传播能力是否存在差异，且该差异是否与可能促进病原体多样性的毒力权衡效应或毒力上限相符。我们借助实验操控手段，利用16株野外采集的病毒分离株复刻了自然越冬感染过程。各病毒分离株的幼虫感染率存在显著差异，进而导致越冬传播速率各不相同。此外，致死幼虫数量更多的分离株，其未产生感染性粒子的幼虫早期死亡率也更高，这与高毒力存在适应性代价的结论一致。因此，本研究结果证实存在这样一种适应性代价：即便对于高毒力病原体而言，该代价也可能为毒力设定上限。