University of Florida, Department of Entomology and Nematology, Florida Medical Entomology Laboratory, Vero Beach, Florida, United States of America.
PLoS Negl Trop Dis. 2020 Nov 17;14(11):e0008846. doi: 10.1371/journal.pntd.0008846. eCollection 2020 Nov.
Zika virus (ZIKV) is an emerging mosquito-borne pathogen that can cause global public health threats. In the absence of effective antiviral medications, prevention measures rely largely on reducing the number of adult mosquito vectors by targeting juvenile stages. Despite the importance of juvenile mosquito control measures in reducing adult population size, a full understanding of the effects of these measures in determining mosquito phenotypic traits and in mosquito-arbovirus interactions is poorly understood. Pyriproxyfen is a juvenile hormone analog that primarily blocks adult emergence, but does not cause mortality in larvae. This mechanism has the potential to work in combination with other juvenile sources of mortality in nature such as predation to affect mosquito populations. Here, we experimentally evaluated the effects of juvenile exposure to pyriproxyfen and predatory mosquito Toxorhynchites rutilus on Aedes aegypti phenotypes including susceptibility to ZIKV infection and transmission. We discovered that combined effects of pyriproxyfen and Tx. rutilus led to higher inhibition of adult emergence in Ae. aegypti than observed in pyriproxyfen or Tx. rutilus treatments alone. Adult body size was larger in treatments containing Tx. rutilus and in treatments mimicking the daily mortality of predation compared to control or pyriproxyfen treatments. Susceptibility to infection with ZIKV in Ae. aegypti was reduced in predator treatment relative to those exposed to pyriproxyfen. Disseminated infection, transmission, and titers of ZIKV in Ae. aegypti were similar in all treatments relative to controls. Our data suggest that the combination of pyriproxyfen and Tx. rutilus can inhibit adult Ae. aegypti emergence but may confer a fitness advantage in survivors and does not inhibit their vector competence for ZIKV relative to controls. Understanding the ultimate consequences of juvenile mosquito control measures on subsequent adults' ability to transmit pathogens is critical to fully understand their overall impacts.
寨卡病毒（ZIKV）是一种新兴的蚊媒病原体，可能对全球公共卫生构成威胁。在缺乏有效抗病毒药物的情况下，预防措施主要依赖于通过针对幼虫阶段来减少成蚊媒介的数量。尽管减少成蚊数量的控制措施对于降低成虫种群规模非常重要，但人们对这些措施在确定蚊子表型特征和蚊-虫媒病毒相互作用方面的影响的了解还很有限。吡丙醚是一种保幼激素类似物，主要阻止成虫出现，但不会导致幼虫死亡。这种机制有可能与自然中其他幼虫致死源（如捕食）结合使用，从而影响蚊子种群。在这里，我们通过实验评估了幼虫接触吡丙醚和捕食性蚊子三带喙库蚊对埃及伊蚊表型（包括对寨卡病毒感染和传播的易感性）的影响。我们发现，吡丙醚和三带喙库蚊联合作用导致埃及伊蚊成虫出现率的抑制率高于单独使用吡丙醚或三带喙库蚊处理时的抑制率。含有三带喙库蚊的处理以及模拟捕食每日死亡率的处理中的成蚊体型比对照或吡丙醚处理中的成蚊体型更大。与暴露于吡丙醚的蚊子相比，感染寨卡病毒的埃及伊蚊的易感性在捕食者处理中降低。寨卡病毒在埃及伊蚊中的播散感染、传播和滴度在所有处理中与对照相比相似。我们的数据表明，吡丙醚和三带喙库蚊的组合可以抑制埃及伊蚊成虫的出现，但可能会赋予幸存者生存优势，并且不会像对照那样抑制它们对寨卡病毒的媒介效能。了解对幼蚊控制措施对随后成虫传播病原体能力的最终影响，对于全面了解其总体影响至关重要。
