ARS | Publication request: Biological and molecular characterization of Hessian fly (Diptera: Cecidomyiidae) from Israel

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 11, 2012
Publication Date: N/A

Interpretive Summary: Hessian fly is an important pest of wheat in the southeastern United States; however, its center of origin is the Fertile Crescent region of the Middle East where it coevolved with wheat. From this center of origin Hessian fly has been dispersed to Europe, the Mediterranean basin, and North America. The most effective and economical control of Hessian fly is through deployment of genetically resistant wheat. Unfortunately, the deployment of single dominant resistance genes places a selection pressure on Hessian fly field populations that leads to the appearance of biotypes that can overcome formerly resistant wheat. Understanding the ancestry of Hessian fly from the Middle East and its ability to overcome different genes for resistance in wheat will aid in understanding the ability of Hessian fly populations in the United States to overcome deployed genes for resistance. We have studied Hessian fly collections from five different locations in Israel. These studies have documented that Hessian fly from Israel is virulent to (can overcome) 11 resistance genes found in wheat. This is surprising since there has never been a program to deploy genes for resistance in Israel. The selection pressure that resulted in virulence in the Israeli Hessian fly is currently unknown; however, one hypothesis is that resistance genes in wild wheat in Israel may have been the source of the selection pressure. Studies are ongoing to clone genes for virulence from the Israeli Hessian fly to see how they compare structurally to genes for virulence in populations in the United States. Knowledge gained from this study will help breeders and scientists facing the challenge of ensuring the durability of resistant wheat better understand how Hessian fly overcomes resistance in wheat. The agricultural community (crop producers and commodity groups) will benefit from improved pest control that increases yield and quality without increasing costs.

Technical Abstract: Morphological evaluation of adults emerging in 5 field collections from Israel supported they were Hessian fly. One of the field collections from Israel was successfully established in culture and a free choice ovipositional preference test with barley and wheat documented females overwhelmingly preferred to oviposit on wheat. DNA Barcoding results using cytochrome c oxidase subunit I (COI) documented that 4 of the 5 Israeli collections averaged only 0.45% divergence compared to Hessian fly collections from the United States and Syria. However, barcodes for the Zikim, Israel collection showed on average 3.52% divergence from the other Israeli collections as well as the collections from the United States and Syria. In evaluations of virulence the Israeli Hessian fly in culture was virulent to 11 of the 19 resistance (R) genes tested and complementation analysis documented that for 4 of the R genes tested the Israeli Hessian fly shared loci for virulence with Hessian fly from the United States. Hessian fly infestations from 7 fields in Israel were all greater than the 5 – 8% levels that result in significant yield losses. Microsatellite genotyping of the 5 Hessian fly collections from Israel revealed two populations. One population was comprised of the 3 collections from the northern Negev and the other population comprised the 2 collections from the southern Coastal Plains Region. Results are discussed from the perspective of contrasting the Israeli Hessian fly collections with those from the United States and Syria.