Date September 5, 1991

Title of Project Developing Temperature Regimes to Limit Whitefly and Aphid Population Growth

Institution where work is being conducted University of Minnesota

Amount of Endowment Grants $10,213
Covering Period 1/91 to 12/91

Anticipated Date of Project Completion/Final Report September 1991

Individual(s) Conducting Project:

(List Project Leader First)

John Erwin - Title Assistant Professor

Telephone Number 612-624-9703

Mark Ascerno - Title Associate Professor

Developing Temperature Regimes to Limit Whitefly and Aphid Population Growth

John E. Erwin and Mark Ascerno

University of Minnesota

Progress Report to the American Floral Endowment, 9/5/91

A. Project Objectives:

1) To determine how day/night temperature, regimes affect the rate of development and the

reproductive potential of the white fly and aphid.

2) To distribute this information in a timely fashion in the form of publications and

presentations.

B. Summary of Work Conducted:

White fly have been raised in growth chambers under 16 different day/night temperature

regimes. Photoperiod was maintained at 12 hours.

C. Results to Date:

1) Functions have been developed which predict the rate of each stage of white fly

development as related to temperature and establish predictive functions for insecticide application

which maximizes white fly mortality. These functions can be used by growers using greenhouse

environmental control computers and/or growers with ‘hand’ calculators who monitor their

greenhouse temperatures to help control white fly populations.

2) An 86′F night temperature is detrimental to white fly development when raised under a

12 hour photoperiod.

3) Results of this experiment were presented at The American Entomology Association

Meetings this winter. The American Floral Endowment was recognized for its contribution to this

work.

D. Future Plans Covered by the Endowment Grant:

1) We are currently conducting the experiment to determine day/night temperature effects

on aphid growth and development under a 12 hour photoperiod.

2) We are currently conducting experiments on day/night temperature effects on both white

fly and aphid development under an 8 hour photoperiod. This work is in addition to the original

work funded by the American Floral Endowment. We feel that the additional experiments will

allow us to predict white fly and aphid development in a greater range of environmental conditions.

In addition, it is very possible that the response of the white flies and aphids to day/night

temperature regime may vary depending on the photoperiod.

3) Lastly, we will run a single experiment to look at how a cool morning pulse in

temperature affects white fly and aphid development.

4) Funding for items 2 and 3 is beyond that requested from the Endowment and will be

acquired for the Minnesota Agriculture Experiment Station. We feel that this work should be

included in this project to complete the study.

E. Anticipated Benefits for Floral industry:

1) An understanding of how day/night temperatures can be used to help control white fly

and aphid development may allow us to decrease pesticide applications. Alternative temperature

regimes may be developed which maximize inhibition of insect development while not greatly

affecting crop production.

2) Information on how day/night temperature effect white fly and aphid development will

allow us to predict when the potential for white fly and aphid infestation and population growth is

greatest.

3) We may be able to apply some of this information for control of other pests such as

thrips and red spider mite.

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