פרופ' ינון שרף

I completed my Ph.D. at Ben-Gurion University in 2009 and studied the hunting behavior, its consequences for growth and comparison of populations of antlions – small insects that dig pit-traps in the sand and ambush their prey. I then continued in a three-year post-doc training at the University of Munich and the University of Mainz, Germany, studying the interactions between different parasites and their cavity-dwelling ant hosts, living in sticks and acorns in the European forest. I joined the Faculty of Life Sciences in October 2012. My lab studies the behavior, life history and ecology of insects. We currently focus on three main themes: learning & foraging, habitat selection and the ecology of stress (please .see below for more).

We study the behavior and ecology of insects using various insect models, such as antlions, ants, flies, and beetles. We engage with various questions, such as what is the optimal way to obtain food, when should an insect mate and reproduce, and how to balance between conflicting energetic demands, such as feeding and reproduction. Our lab mainly asks why animals behave the way they do, and how the observed behaviors help maximize survival and reproduction. We mostly perform controlled lab experiments. We nevertheless also work in the field, in the natural habitat of the studied animals, and use modeling and other methods to answer our questions.

Our recent work deals with three main topics:

(1) Learning & foraging: Do animals improve their performance while searching for food with experience? If yes, do they also later forget? Do animals learn in the absence of a reward? What is the effect of motivation on learning? What is the value of learning as a mechanism to win over food resources? What is the effect of group size on learning?

An example includes our project of spatial learning in desert ants. Desert ants are excellent navigators and searching in mazes is a suitable way to test their navigation and learning abilities. They improve their maze-solving time with experience but also forget after some days how to solve the maze. Learning to solve the maze assists the ants while competing against other colonies.

(2) Habitat selection: Do animals choose to settle in habitats that maximize their success? Do they move out when the habitat starts deteriorating? Do animals base their decisions on a single criterion or take several ones into consideration? What happens if such criteria contradict each other? What is the cost of choosing a habitat of low quality?

An example includes the habitat selection procedure of wormlions. Wormlions are insects that dig pit-traps in the sand to hunt other insects. Before hunting, they need first to decide where to dig their pit-trap. Wormlions prefer habitats that maximize their hunting success and take into account several considerations when choosing their habitat.

(3) Ecology of Stress. How do insects respond to stressful conditions? Do they acclimate to such conditions? If yes, at which cost? Stress is clearly harmful, but can it be beneficial under some circumstances? Do stressed parents produce stressed offspring?

An example includes the effect of starvation and exposure to low temperatures on the behavior, survival, and reproduction of the red flour beetles. The red flour beetle is a common pest of grain and flour and an excellent insect to study these questions. Stressed parents even change the phenotype of their offspring.

Selected recent publications (June 2021):

For a full list of publications, please visit our website here: http://inonscharflab.weebly.com

Learning & foraging in ants:

(1) Saar M, Gilad T, Kilon-Kallner T, Rosenfeld A, Subach A, Scharf I (2017) The interplay between maze complexity, colony size, learning and memory in ants while solving a maze: a test at the colony level. PLoS One 12:e0183753.

(2) Bega D, Samocha Y, Yitzhak N, Saar M, Subach A, Scharf I (2020) Non-spatial information on the presence of food elevates search intensity in ant workers, leading to faster maze solving in a process parallel to spatial learning. PLoS One 15: e0229709 

(3) Saar M, Eyer PA, Kilon-Kallner T, Hefetz A, Scharf I (2018) Within-colony genetic diversity differentially affects foraging, nest maintenance, and aggression in two species of harvester ants. Scientific Reports 8:13868.

Habitat selection in wormlions and other sit-and-wait predators:

(1) Adar S, Dor R, Scharf I (2016) Habitat choice and complex decision making in a trap-building predator. Behavioral Ecology 27:1491-1498.

(2) Scharf I, Gilad T, Bar-Ziv MA, Katz N, Gregorian E, Pruitt JN, Subach A (2018) The contribution of shelter from rain to the success of pit-building predators in urban habitats. Animal Behaviour 142:139-145.

(3) Scharf I (2020) Factors that can affect the spatial positioning of large and small individuals in clusters of sit-and-wait predators. American Naturalist 195: 649-663.

Ecology of stress in flour beetles:

(1) Gilad T, Koren R, Moalem Y, Subach A, Scharf I (2018) Effect of continuous and alternating episodes of starvation on behavior and reproduction in the red flour beetle. Journal of Zoology 305:213-222.

(2) Scharf I, Wertheimer KO, Xin J, Gilad T, Goldenberg I, Subach A (2019) Context-dependent effects of cold stress on behavioral, physiological, and life-history traits of the red flour beetle. Insect Science 26:142-153.

(3) Gilad T, Scharf I (2019) Separation between maternal and paternal effects on offspring following exposure of adult red flour beetles to two stressors. Ecological Entomology 44:494-501.