Gordon Johnalyn M, Šobotník Jan, Chouvenc Thomas
Entomology and Nematology Department Ft. Lauderdale Research and Education Center Institute of Food and Agricultural Sciences University of Florida Davie FL USA.
Faculty of Tropical AgriSciences CULS Prague Czech Republic.
Ecol Evol. 2020 Aug 16;10(18):10095-10104. doi: 10.1002/ece3.6669. eCollection 2020 Sep.
Cuticular hydrocarbons (CHCs) have, in insects, important physiological and ecological functions, such as protection against desiccation and as semiochemicals in social taxa, including termites. CHCs are, in termites, known to vary qualitatively and/or quantitatively among species, populations, castes, or seasons. Changes to hydrocarbon profile composition have been linked to varying degrees of aggression between termite colonies, although the variability of results among studies suggests that additional factors might have been involved. One source of such variability may be colony age, as termite colony demographics significantly change over time, with different caste and instar compositions throughout the life of the colony. We here hypothesize that the intracolonial chemical profile heterogeneity would be high in incipient termite colonies but would homogenize over time as a colony ages and accumulates older workers in improved homeostatic conditions. We studied caste-specific patterns of CHC profiles in colonies of four different age classes (6, 18, 30, and 42 months). The CHC profiles were variable among castes in the youngest colonies, but progressively converged toward a colony-wide homogenized chemical profile. Young colonies had a less-defined CHC identity, which implies a potentially high acceptance threshold for non-nestmates conspecifics in young colonies. Our results also suggest that there was no selective pressure for an early-defined colony CHC profile to evolve in termites, potentially allowing an incipient colony to merge nonagonistically with another conspecific incipient colony, with both colonies indirectly and passively avoiding mutual destruction as a result.
在昆虫中，表皮碳氢化合物（CHCs）具有重要的生理和生态功能，例如防止脱水以及作为包括白蚁在内的社会性类群中的信息化学物质。在白蚁中，已知CHCs在物种、种群、品级或季节之间存在质和/或量的差异。碳氢化合物谱组成的变化与白蚁群体之间不同程度的攻击性有关，尽管研究结果的变异性表明可能涉及其他因素。这种变异性的一个来源可能是群体年龄，因为白蚁群体的种群统计学特征会随着时间显著变化，在群体的整个生命周期中具有不同的品级和龄期组成。我们在此假设，初建的白蚁群体中群体内化学谱的异质性会很高，但随着群体变老并在改善的稳态条件下积累年长的工蚁，这种异质性会随着时间推移而趋于同质化。我们研究了四个不同年龄组（6个月、18个月、30个月和42个月）群体中CHC谱的品级特异性模式。在最年轻的群体中，CHC谱在不同品级之间存在差异，但逐渐趋向于全群体同质化的化学谱。年轻群体的CHC特征不太明确，这意味着年轻群体对非巢伴同种个体的接受阈值可能较高。我们的结果还表明，白蚁中不存在促使早期确定的群体CHC谱进化的选择压力，这可能使一个初建群体能够与另一个同种初建群体非对抗性地合并，结果是两个群体都间接且被动地避免了相互毁灭。
