Animals have evolved foraging strategies to acquire blends of nutrients that maximize fitness traits. In social insects, nutrient regulation is complicated by the fact that few individuals, the foragers, must address the divergent nutritional needs of all colony members simultaneously, including other workers, the reproductives, and the brood. Here we used 3D nutritional geometry design to examine how bumblebee workers regulate their collection of 3 major macronutrients in the presence and absence of brood. We provided small colonies artificial nectars (liquid diets) and pollens (solid diets) varying in their compositions of proteins, lipids, and carbohydrates during 2 weeks. Colonies given a choice between nutritionally complementary diets self-selected foods to reach a target ratio of 71% proteins, 6% carbohydrates, and 23% lipids, irrespective of the presence of brood. When confined to a single nutritionally imbalanced solid diet, colonies without brood regulated lipid collection and over-collected protein relative to this target ratio, whereas colonies with brood regulated both lipid and protein collection. This brood effect on the regulation of nutrient collection by workers suggests that protein levels are critical for larval development. Our results highlight the importance of considering bee nutrition as a multidimensional phenomenon to better assess the effects of environmental impoverishment and malnutrition on population declines.

A major difficulty in studying the behaviour of social insects, such as bees, is to collect quantitative data on large numbers of individuals and over long periods of time, in sometimes dark and not easily accessible nests. Over the past decade, connected hives equipped with large sets of sensors to monitor real-time data about bee colony health and environmental conditions have been increasingly used in fundamental research, precision beekeeping and outreach programs. Here, we argue that combining these connected hive systems with automated movement tracking devices to obtain long-term data about the behaviour of bees inside and outside the hive can lead to major breakthroughs by helping discover new behaviours and compare data across labs and species. First, we describe the main sensors and hive parameters commonly used in connected hives used for honey bee and bumblebee colonies. Next, we discuss how developing more integrated systems connecting bees, hives and their environment, will help ask novel fundamental questions on bee behaviour and ecology.

Insect diet refers to the food usually eaten by an insect for growth, tissue maintenance, and reproduction, as well as the energy necessary to main-tain these functions.