Date August 1992

Title of Project Aerial Transmission of Foliar Bacterial Pathogens by Fungus Gnats and Shore Flies

Institution where work is being conducted University of Arizona

Amount of Endowment Grant $ 16,000
Covering Period Jan. 1992 to Dec. 1992

Anticipated Date of Project Completion/Final Report February 1993

Individual(s) Conducting Project:

(List Project Leader First)

M.E. Stanghellini - Title Professor of Plant Pathology

Telephone Number 602-621-7163

Aerial Transmission of Foliar Bacterial Pathogens by Fungus Gnats and Shore Flies

M. E. Stanghellini

University of Arizona

Progress Report to the American Floral Endowment, 8/92

A. Project Objectives:

To elucidate the role of fungus gnats and shore flies as

aerial vectors of bacterial pathogens which cause foliar diseases

of greenhouse crops.

B. Data Suitable for Dissemination:

We have shown that plant pathogenic bacteria can be

transmitted by adult shore flies. We are in the process of

showing that transmitted bacteria can cause disease.

C. Results to Date (new information):

Larvae of shore flies ingest pathogenic bacteria and the

bacteria persisted,in the gut of the larvae, through pupation and

emerging adults are internally infested. Frass produced by such

adults contained the bacteria. Frass deposits were visually

observed on leaves of test plants frequented by infested adults,

thus establishing that shore flies can transmit these bacteria.

Bacteria tested were Erwinia carotovora and Pseudomonas chicorii.

Spontaneous mutant strains of each bacterium, resistant to

rifampicin, were employed in these studies which facilitated their

identification and biology.

D. Future Plans Covered by the Endowment Grant:

We have had unexpected difficulties in maintaining fungus gnat

colonies and need to verify that these insects, in addition to

shore flies, can acquire and transmit these bacteria. Our next

objective is to prove that bacteria contained in frass and

deposited on leaves of host plants are, in fact, the source

responsible for leaf infection. Such studies are currently under

investigation.

E. Anticipated Benefits for Floral Industry:

Knowledge of the role of shore flies and fungus gnats in the

epidemiology of foliar bacterial pathogens will result in

recognition of the necessity for the control of greenhouse

infestations by these insects.

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