Are body size and volatile blends honest signals in orchid bees?

Abstract

Secondary sexual traits may convey reliable information about males’ ability to resist pathogens and that females may prefer those traits because their genes for resistance would be passed on to their offspring. In many insect species, large males have high mating success and can canalize more resources to the immune function than smaller males. In other species, males use pheromones to identify and attract conspecific mates, and thus, they might function as an honest indicator of a male's condition. The males of orchid bees do not produce pheromones. They collect and store flower volatiles, which are mixed with the volatile blends from other sources, like fungi, sap and resins. These blends are displayed as perfumes during the courtship. In this study, we explored the relationship between inter‐individual variation in body size and blend composition with the males’ phenoloxidase (PO) content in Euglossa imperialis. PO content is a common measure of insect immune response because melanine, its derived molecule, encapsulates parasites and pathogens. Body size and blend composition were related to bees’ phenolic PO content. The inter‐individual variation in body size and tibial contents could indicate differences among males in their skills to gain access to some compounds. The females may evaluate their potential mates through these compounds because some of them are reliable indicators of the males’ capacity to resist infections and parasites.

The Birth-and-Death Evolution of Cytochrome P450 Genes in Bees

“…Male orchid bees collect a wide range of chemical compounds, many of which are expected to be toxic to bees. Collection of these compounds, therefore, could act as an indicator of male quality, through their ability to handle and detoxify these compounds ( Eltz et al 1999 ; Arriaga-Osnaya et al 2017 ). We may expect adaptation at the molecular level, perhaps in the form of an increased P450 repertoire, or increased expression levels, to be able to detoxify such a wide range of compounds.…”

Steep converse Bergmann's cline in a carrion beetle: between‐ and within‐population variation in body size along an elevational gradient

“…Outstanding pivotal position of body size in evolutionary biology and ecology research is given in particular by close relationships between body size and fitness components. For example, larger females are more fecund (Sota, ; Honěk, ; Marshall et al ., ; Pincheira‐Donoso & Hunt, ), whereas larger males often have a higher mating success (Savalli & Fox, ; Arriaga‐Osnaya et al ., ; Avila, Withers & Holwell, ). In addition, larger sized insects are frequently able to cope better with stressful environments.…”

Social Behavior, Ovary Size, and Population of Origin Influence Cuticular Hydrocarbons in the Orchid Bee Euglossa dilemma

“…S4). This has been used elsewhere to serve as a rough estimate of the total abundance of material in a chemical sample (Arriaga-Osnaya et al, 2017). Given that all behaviors were extracted and analyzed with the same approach, this suggests that newly emerged females are likely still in the process of secreting CHCs and have not reached the amount typical of most females performing normal adult nest behaviors.…”