Colony‐level chemical profiles do not provide reliable information about colony size in the honey bee

Abstract

1. Chemical communication facilitates colony function across social insects, providing workers with information about individual and colony state. Although workers use chemical cues to detect developmental transitions in individuals, it is unknown whether workers can also use colony‐level chemical profiles to detect the developmental state of their colony. Indeed, it is largely unknown how colony‐level chemical profiles change as colonies grow and develop.2. Reproductive onset is a major developmental transition and, in the honey bee, Apis mellifera, colonies must surpass a threshold colony size before workers will invest in reproduction. Given the ubiquity of chemical communication, the present study investigated whether colony‐level chemical profiles change with colony size.3. Chemical compounds deposited by workers of three colony sizes (5000, 10 000, 15 000 workers) collected over a 4‐day time‐series (0, 12, 24, 48, 72, and 96 h), as well as worker cuticular lipids, were sampled.4. In total, 26 compounds deposited on nest surfaces and 20 compounds in worker cuticular lipids were identified; it took up to 24 h for sampled nest surfaces to reach saturation in the number and amount of deposited compounds.5. Among these compounds, no qualitative or quantitative indicators of colony size were found, suggesting that deposited chemical compounds are not semiochemicals in this context. Volatile pheromones have also been shown previously to not play a role in signaling colony size. Therefore, honey bee workers are unlikely to use deposited chemical cues to detect colony size, and must rely instead on other modalities, such as physical cues of worker density.