Kutch Ian C, Sevgili Hasan, Wittman Tyler, Fedorka Kenneth M
University of Central Florida, Biological Sciences Building, 4110 Libra Drive, Orlando, FL 32816, USA.
Ordu University, Faculty of Arts & Sciences, Department of Biology, Cumhuriyet Campus, 52200 Ordu, Turkey.
J Exp Biol. 2014 Oct 15;217(Pt 20):3664-9. doi: 10.1242/jeb.106294. Epub 2014 Aug 21.
As temperatures change, insects alter the amount of melanin in their cuticle to improve thermoregulation. However, melanin is also central to insect immunity, suggesting that thermoregulatory strategy may indirectly impact immune defense by altering the abundance of melanin pathway components (a hypothesis we refer to as thermoregulatory-dependent immune investment). This may be the case in the cricket Allonemobius socius, where warm environments (both seasonal and geographical) produced crickets with lighter cuticles and increased pathogen susceptibility. Unfortunately, the potential for thermoregulatory strategy to influence insect immunity has not been widely explored. Here we address the relationships between temperature, thermoregulatory strategy and immunity in the fruit fly Drosophila melanogaster. To this end, flies from two separate Canadian populations were reared in either a summer- or autumn-like environment. Shortly after adult eclosion, flies were moved to a common environment where their cuticle color and susceptibility to a bacterial pathogen (Pseudomonas aeruginosa) were measured. As with A. socius, individuals from summer-like environments exhibited lighter cuticles and increased pathogen susceptibility, suggesting that the thermoregulatory-immunity relationship is evolutionarily conserved across the hemimetabolous and holometabolous clades. If global temperatures continue to rise as expected, then thermoregulation might play an important role in host infection and mortality rates in systems that provide critical ecosystem services (e.g. pollination), or influence the prevalence of insect-vectored disease (e.g. malaria).
随着温度变化，昆虫会改变其表皮中黑色素的含量以改善体温调节。然而，黑色素在昆虫免疫中也起着核心作用，这表明体温调节策略可能通过改变黑色素途径成分的丰度间接影响免疫防御（我们将这一假设称为体温调节依赖性免疫投入）。蟋蟀Allonemobius socius可能就是这种情况，在温暖的环境（包括季节性和地理性）中产生的蟋蟀表皮颜色较浅，对病原体的易感性增加。不幸的是，体温调节策略影响昆虫免疫的可能性尚未得到广泛研究。在这里，我们研究了果蝇Drosophila melanogaster中温度、体温调节策略和免疫之间的关系。为此，将来自两个不同加拿大种群的果蝇饲养在类似夏季或秋季的环境中。成虫羽化后不久，将果蝇转移到一个共同的环境中，测量它们的表皮颜色和对细菌病原体（铜绿假单胞菌）的易感性。与Allonemobius socius一样，来自类似夏季环境的个体表皮颜色较浅，对病原体的易感性增加，这表明体温调节与免疫的关系在渐变态和全变态类群中在进化上是保守的。如果全球气温继续如预期那样上升，那么体温调节可能在提供关键生态系统服务（如授粉）的系统中的宿主感染和死亡率中发挥重要作用，或者影响昆虫传播疾病（如疟疾）的流行率。
