Taxonomy, phylogeny and ecology of gall midges


Gall midges (family Cecidomyiidae) constitute the largest and most

diverse group of gall-inducing insects. Roughly 70% of the species in the

family develop in galls, which the larvae induce in plants from many different families. Some species form conspicuous and complex galls such as those seen in the picture above, others form simple or inconspicuous galls, and many others develop in plant tissues without gall formation. Most gall midges are very host specific, such that each species is associated with a single host plant or with a few closely related species of  plants. While the gall-midge fauna of Europe and North America isrelatively well known, that of other parts of the world is poorly studied and many species remain to be discovered and described.

     We study different groups of gall midges from Israel and other parts of the world, with special emphasis on taxa that are associated with the plant families Chenopodiaceae, Asteraceae and Fagaceae. Many of the species we work on are new to science and their basic life history is unknown yet. We use morphological and molecular methods to study their taxonomy and phylogeny, and conduct field and laboratory work to learn about their life history and ecology.

Speciation in phytophagous insects and their natural enemies

Phytophagous insects constitute one of the largest and most successful

groups in nature in terms of biological diversity. Many of them are

specialized herbivores and their adaptations to specific host plants can lead

to reproductive isolation and eventually to the formation of distinct species.

We study behavioral and ecological factors that contribute to reproductive

isolation in gall midges, such as mate choice, oviposition choice, allochronic

activity and hybrid fitness. We also investigate the role of natural enemies

in this process by documenting attack levels on galls in the wild and by testing

preference and performance of the enemies in greenhouse and laboratory experiments.

Ecology and taxonomy of galling insects on oaks

The diversity and complexity of cynipid galls is second only to those of

cecidomyiid galls. The great majority of gall wasps are associated with

oaks, and their galls on these trees are some of the most common and

striking in Mediterranean oak forests. The five native oak species in Israel

host at least 70 species of gall wasps and gall midges, the taxonomic status and basic life history for many of which is poorly known. We recently completed a study on the taxonomy of oak cynipids and the influence of habitat fragmentation on their populations on the Thabor oak (Quercus ithaburensis) in Israel. We plan further systematic and ecological studies on the rich community of natural enemies of galling insects on oaks as well as on the systematics and life history of gall-midges on these plants. 

Aquatic insects as bio-indicators for water quality

Mayflies (order Ephemeroptera) and caddisflies (order Trichoptera) are

insects whose nymphal stages develop in aquatic habitats, particularly

streams and rivers. Because the immature stages of many species are sensitive to changes in

environmental conditions, these insects play a major role in various indices

and other methods for the evaluation of aquatic ecological systems and for monitoring anthropogenic disturbances to such habitats. The mayfly fauna of Israel has been recently revised and is currently estimated at about 30 species from 8 families, although continuing study may raise this number. By contrast, the Israeli caddisfly fauna has not been studied for several decades and we currently initiate a comprehensive survey of this group in diverse aquatic habitats throughout Israel in order to substantiate the knowledge on the local fauna. We intend to revisit the systematics of Israeli caddisflies, associate the little known larvae with the adult stages, and characterize the ecological requirements of all species. This work is expected to promote the development of tools for the assessment of stream conditions based on mayfly and caddisfly community composition, as is customary in other parts of the world.

Biological control of invasive weeds

Biological invasions constitute one of the major threats to biodiversity

worldwide. Invasive weeds are plants that were introduced (accidentally

or deliberately) from their native land into other parts of the world and

now aggressively displace native plants and animals due to their

remarkable dispersal and reproduction abilities, lack of competition, and lack of local natural enemies. Such invasions often lead to fundamental changes in local ecosystems, including protected areas. Classical biological control is the prevailing practice for the biocontrol of weeds, especially when the invasive plant has spread out of control and cannot be eradicated locally. One of the most aggressive and notorious weeds in Israel is the Australian tree Acacia saligna, which was introduced for dune reclamation in the early 1900s and has quickly spread from the coastal plain to other parts of the country. For the past few years, we have been investigating the use of seed-destroying weevils as biological control agents against Acacia saligna in Israel with the hope that the beetles will help to stop the dispersal of trees and aid in their eradication from threatened habitats. Following successful quarantine experiments with the weevils over the past few years, we recently launched the second phase of this study, which includes the release of the beetles in Israel and monitoring of their establishment in disturbed natural habitats.