Maps Predict Path of Destructive Citrus
Pest By Alfredo
Flores May 22, 2007
The distribution of diaprepes root weevils (Diaprepes
abbreviatus) is constrained by temperature, a key finding that could be
vital to predicting and limiting the spread of this pest, according to
Agricultural Research Service (ARS)
scientists in Ft. Pierce, Fla.
The team of researchers, led by entomologist
Lapointe at the ARS Subtropical Insects Research Unit (SIRU)
in Fort Pierce, used probability maps to make the discovery.
Since its arrival in 1964, the diaprepes root weevil has been a major
contributor to the decline of Florida's citrus industry. The pest's ability to
feed on more than 200 host plant species has aided its spread throughout
citrus-producing areas of peninsular Floridathe southern two-thirds of
The probability maps use a combination of soil and air temperatures to
delineate the current distribution of both the diaprepes root weevil and of
parasitoid insects that attack its eggs and have potential to serve as
biological controls of the pest.
The researchers have shown that adult female weevils stop producing
eggs at 59 degrees Fahrenheit, and the eggs themselves are highly susceptible
to cold. Eggs already laid become nonviable when exposed to 53 degrees F for
4.2 daysabout 100 hours. This explains why egg parasitoids of D.
abbreviatus haven't been able to establish themselves in northern Florida.
Using this knowledge, Lapointe and his team worked with scientists
from the Animal and Plant Health Inspection
Service's Center for Plant Health
Science and Technology to develop probability maps to describe the current
diaprepes distribution in Florida and in portions of Texas, Arizona and
California that are most susceptible to its establishment. The maps will be
used to guide survey and control efforts in those states.
Already, the parasites Quadrastichus haitiensis from Puerto
Rico and Aprostocetus vaquitarum from the Dominican Republicboth
introduced into southern Florida to control the weevilare considered to
be successfully established there.
about the research in the May/June 2007 issue of Agricultural Research
ARS is the U.S. Department of
Agriculture's chief in-house scientific research agency.