What limits the reproductive success of insects in the field?
Insects constitute a significant proportion of biological diversity on earth, and their influence on mankind is enormous. However, the small size and high mobility of many insects makes it difficult to study them under field conditions. This limits our ability to answer basic questions on insect ecology and evolution and to promote their use for our own benefit. We apply different methods to study limits to the reproductive success of insects in the field. These methods allow investigating the effects of individual variation (body size, physiological state), environmental conditions (temperature, food availability) and anthropogenic influences (land management) on the success, life history and behavior of insects in the field, while promoting their use for biological control.
What is the effect of bacterial endosymbionts on the reproductive success of insects?
Recent scientific developments emphasize the important role of bacterial endosymbionts on the development, ecology and evolution of their insect hosts. Bacterial endosymbionts may be virulent or beneficial for their host. These effects often depend on host state and on the environment. Therefore, it is important to study the effects of endosymbionts under varying, yet realistic, environmental conditions. We apply advanced methods to study the effect of endosymbionts on the success of insects under natural or semi-natural conditions, while promoting their use for biological control of pests and diseases.
The effect of Evrona oil-spill on insect communities
Desert environments are highly impacted by human disturbances such as habitat destruction, over-exploitation of water resources and spill-over of chemicals. Insects are good bio-indicators to detect the outcomes of human disturbances, due to their high diversity and rapid response. We study the effects of a recent oil-spill in Evrona natural reserve on insect communities. For this we compare insect communities on Acacia trees in oil affected vs. unaffected areas. This project is funded by Israel’s National Nature Assessment Program and by the National Park Authorities.
Insect communities in agricultural systems in the Negev
Agricultural desert systems are characterized by an extreme contrast between the green productive agricultural fields and the surrounding arid natural habitats. In this project we investigate the community and movement of insects between vineyards and the natural habitat surrounding them in the Negev Desert, while addressing the following questions: Where do the main pests species come from? Where do their natural enemies (predators and parasitoids) come from? What are the main limitations for insect success in agricultural vs. natural habitats? Do insects become locally adapted to these limitations? What can be done to promote efficient control of the pests by their natural enemies while reducing chemical applications?
Ecological tragedy: the collection of parasitized caterpillars by potter wasps
The potter wasp Delta dimidiatipenne lays its eggs in mud chambers provisioned with caterpillars to feed their young. Preliminary observations indicate that many of the caterpillars collected by this wasp are already parasitized by a small gregarious parasitoid wasp. As a result, all players in the interaction perish - the potter wasp young cannot fully exploit the caterpillars and presumably starve to death; and the small parasitoids complete their development, but cannot break out of the mud and remain trapped in the sealed pot. In this project we estimate the frequency of this striking phenomenon, and study mechanisms through which it is maintained, despite the high cost to all players.
Tri-party underground symbiosis between a desert plant, a weevil and their gut-bacteria
The weevil Conorhynchus pistor develops in a mud chamber affixed to the roots of Salsola plants in the Negev Desert. The weevil harbors nitrogen fixing bacteria, and plants with weevils on their roots were shown to have higher nitrogen contents. In this project we survey Salsola populations to characterize the frequency and distribution of this unique interaction and conduct manipulative field and lab experiments to explore the interaction between that plant and the weevil. Molecular and chemical tools are used to identify the nitrogen fixing bacteria and their activity.
Brown widow spider invasion genetics and species interactions
The brown widow spider, Latrodectus geometricus, is a spider with neurotoxic venom native to South Africa which currently has successfully established populations worldwide, including in Israel, where brown widows were introduced in 1980 and have since spread south into the Negev Desert. Parasitoid flies and wasps, which lay eggs in developing spider egg sacs, are among the main predators of Latrodectus spiders. In this project, we evaluate the mechanisms and ecology of parasitoid wasp infection and how it may differentially affect invasive brown widow spiders and native widow spiders in Israel. To understand how brown widows have been transported to and successfully colonized new habitats, we investigate connectivity and genetic differentiation among native and invasive populations using Single Nucleotide Polymorphisms (SNPs).