Drosophila suzukii update June 7, 2010

The current status of Drosophila suzukii is that although there have been no outbreaks fresh market strawberries or blueberries in Florida during the 2010 season, the population continues to steadily expand in the State.

 

Looking at the weekly number of positive traps since the first find on August 4, 2009, the numbers are constantly changing in response to factors limiting population growth such as weather and host availability (Fig 1).  Until late December 2009, the population began to increase dramatically when the first freezing weather of an unusually cold winter arrived in Florida.  The population remained low and did not begin to recover until after the prolonged freezes and cooler weather had subsided by week 27.  As the weather warmed and many fruit hosts became available in the spring the population again increase to record highs of above 50 positive traps weekly.  Then, as the warm weather began to intensify and many fruit hosts began to disappear, the local populations appear to be diminishing again.

 

A better indication of the general population trend is to look at the steady increase in the cumulative positive finds since the introduction of this new pest in Florida.  The population trend is good match for a power regression with an average weekly number of new positive finds at around 10.5 (Fig 1).

 

 

FIG 1

 

As we head into the hot and humid summer months, the number of Florida counties with positive finds for D. suzukii is now at 24.  There is now some seasonal fruit fly trapping occurring in the northern half of the state during the summer months.  We hope to be alert for them in our fruit fly multi-lure bait traps and look for possible new host plants, should the population continue to expand northward at the same rate that it has during the first 40 weeks since it was introduced into the State.

FIG 2

 

 

David Dean, Ph.D.

Entomologist

Fruit Fly Laboratory

923 10th Street East

Palmetto, FL 34221

(941) 721-6655