Current research in the lab:

The regulation of reproduction in social insects. Reproduction in social insect societies is dominated by one or a few females and exhibits one of the most fascinating phenomena in social behavior. Such an extreme reproductive skew is maintained by sophisticated behavioral and chemical mechanisms and requires the transfer of genetic traits which encode behaviors that seemingly sabotage their own inheritance, posing a significant challenge to Darwin’s natural selection theory. Research in the lab focuses on the multiple regulatory mechanisms underlying worker reproduction in a social colony, including the queen, nestmates and the brood and the behavioral and chemical means they use in order to regulate reproduction. We are especially interested in how these regulators depend on the social context and in the perception of workers of these signals. This project is funded by NSF CAREER IOS-1942127 to E. Amsalem.

The evolution of reproductive signaling. Insects exhibit remarkably diverse social organizations, from solitary to eusocial, in which a few to millions of individuals form groups and perform tasks collectively. These complex social structures rely on effective communication to properly function. The most common and ancient means of communication, occurring widely among social insects, are chemical signals (pheromones); these are produced by one individual (sender) and are detected by and induce a response in another individual (receiver) of the same species. Pheromones regulate every aspect of social organization, including reproductive division of labor, the signature trait of social societies, and nest maintenance tasks such as brood care, foraging, and defense, which are typically performed by non-reproductive females. But how did reproductive signaling evolve in insects?
Research in the lab focuses on the perception, production, social regulation and biosynthesis of compounds in reproductive signal-producing glands in bees. We are especially interested in the role of ester signaling in bees.

The genetic and physiological factors underlying successful diapause in bumble bee queens. Insects can use diapause to cope with extremes in seasonal environments. However, diapause is a physiologically demanding life-stage that can result in mortality. Research in the lab focuses on the intrinsic and extrinsic factors affecting winter diapause survival in annual social bees, the role of nutrition in regulating successful diapause, and the mechanisms underlying these phenomena.
Picture
We focuses on both the basic science related to diapause in insects and to the ways by which this knowledge can be translated to  conservation strategies. This project is funded by Predoctoral NIFA AFRI ELI Fellowships Grant Program to E. Treanore.
The impact of pesticides on mating behavior. Insect populations are declining worldwide, and exposure to agricultural pesticides is a major contributing factor. Often, this exposure does not cause immediate mortality, but produces sublethal effects that reduce the fitness of non-target insects by affecting their ability to learn, fly, and thermoregulate. A crucial event in the life of insects is mating, which is predominately regulated through specific pheromone blends that guide insects to potential mates and indicate their quality. How pesticides affect mating behavior is unknown, and could have large impacts on insect fitness.

Research in the lab focuses on the effects the neonicitinoid imidacloprid has on mating behavior in bumble bees, and the chemical and physiological mechanisms underlying this effect.
The impacts and underlying mechanisms of carbon dioxide narcosis in bumble bees. Bumble bees are important pollinators of agriculture and wild crops and suffer from global decline in health and productivity of both managed and wild pollinators. Year-round production of bumble bee colonies is managed either by extended cold storage that simulates the natural winter-diapause or by a treatment with CO2 that causes the queens to bypass diapause, initiate ovarian activation and found a colony. Exposure to CO2 has dramatic behavioral and physiological effects in many insect species, including bumble bees. However, the short- and the long-term effects of CO2 treatment on bumble bee queen health and performance, and mechanistic details of CO2-induced onset of reproduction are largely unknown. Research in the lab focuses on the physiological impacts and mechanisms underlying CO2 narcosis in bumble bee queens. This study is funded by the US-Israel Binational Agricultural Research and Development Fund US-5182-19 R to E. Amsalem (Penn State) and Eran Levin (Israel), with R, Schilder (Penn state) as a collaborator.

Larva development and caste determination in bumble bees and the evolution of castes in social insects. Larva development in social insects is largely dependent on the social environment. Totipotent eggs in the honeybee, for example, will develop into either workers or queens depending on the queen presence and the food provided by workers, and in some species of ants, caste is determined by genetic and environmental factors. However, the mechanisms underlying caste determination in other primitively eusocial insects are still mostly elusive. In bumble bees, colony age, location of development within the colony, and the queen presence have all been shown to affect female final body size and caste. However, the larva development and how it is affected by these factors remain unknown. Research in the lab focuses on the development of eggs, larvae and pupae under different social conditions, the way they are affected by nutrition and the social environment, and more broadly on the  social regulation of developing brood and castes in a primitively eusocial species. An exciting project we currently work on is to develop a method for the in-vitro rearing of Bombus impatiens brood.

​Why social insects?

Social groups where reproduction is skewed in favor of selected females represent a fascinating phenomenon that reached its most extreme form in social insects, with a single female dominating reproduction and sterile individuals functioning as helpers. Such an extreme reproductive skew requires the transfer of genetic traits which encode behaviors that seemingly sabotage their own inheritance, posing a significant challenge to Darwin’s natural selection theory. Particularly, why would individuals carry traits that reduce their own fitness and how do genes for altruism spread in the population given that the individuals that carry them do not reproduce. In order to address these questions we study the evolutionary development of complex social behavior and reproductive division of labor, particularly key events that occur in the transition between different social organizations or social phases and the mechanisms regulating and maintaining social complexity and reproduction.


​Why bumble bees?

​among other bees and social insects, bumblebees are the main model system we use in the lab. Primitively (eu)social insect species are great models to study how social complexity evolved and is maintained. They exhibit characteristics of both primitively and advance eusocial insects, and thus, can be used to study the evolutionary transitions from solitary to simple- to complex- sociality and the mechanisms by which such behaviors and reproduction are regulated.
Bumble bees also provide critical commercial and wild pollination services throughout the world. There is an urgent need to improve the health of bumble bee colonies due to world-wide population declines and a documented reduction in health, fertility and productivity of both wild and managed bumble bee colonies. To address this need we study critical life history traits (like diapause and caste determination) underpinning health, performance and productivity of managed bumble bees.