Mosquito control and Florida beekeepers

As Florida continues to recover from the effects of Hurricane Irma, many mosquito control districts in the state are temporarily stepping up their spray programs. It is important to realize how and why this is an important response to strong storms that bring rain and flooding. According to UF urban entomologist Dr. William H. Kern,

The purpose of mosquito control is to protect human and livestock health.  Most of the upcoming spraying or larviciding is to control floodwater mosquitoes… Areas that were dry before the storm and now hold water, are the concern with flood water mosquitoes and these are the areas that are likely to be sprayed.  Swales, depressions, road ruts are examples of places that flood water mosquitoes breed in huge numbers due to the lack of fish to eat the larvae.  Areas flooded by expanding streams, lakes, ponds, and canals produce fewer mosquitoes because mosquito fish are good at spreading with these expanding waters.

What Beekeepers Can Do
Following the below steps can help protect your bee colonies from mosquito sprays.
  1. Temporarily cover your colonies: When you know that your area will be sprayed for mosquito control, loosely cover your colonies during that time. This can be done with a piece of plywood or with a tarp (“tented” like a roof over the colony). DO NOT completely seal up or wrap your colonies! They can quickly overheat and die. Alternatively, colonies can be moved to more protected locations, for example, under a roof overhang or in a garage with a fan blowing.
  2.  Communicate with your local mosquito control district: Widening communication between beekeepers and mosquito control districts can be very beneficial. Make sure that your local district knows where your bees are located; some districts even maintain a list of local apiary locations so that they can notify beekeepers before spraying. You can learn what mosquito control district you are located in here.
  3. Do your research: Not all species of mosquitoes are controlled with the same compounds and not all mosquito controls are harmful to bees. Some impact adult bees but not immature bees; other compounds do not affect honey bees at all! Read the information below from Dr. Kern on how various mosquito controls impact honey bees.

A new female mosquito emerges from a pupal casing in the water. UF/IFAS File Photo

 

Mosquito Treatment Effects on Honey Bees

Mosquito larvicides with no impact on Honey Bees

  • Bacillus thuringiensis var. israelensis (Bti)
  • Bacillus sphaericus 2362  (Culex and Anopheles mosquito larvae are most susceptible.)

Mosquito larvicides with no impact on adult honey bees

  • These could impact bee larvae if brought into the hive with water by foraging workers. Supplying clean water close to the hives can reduce possible risk.
  • Methoprene -Insect Growth Regulator, Juvenile Hormone Analog (e.g. Altosid, Metalarv)
  • Pyriproxyfen -Insect Growth Regulator, Juvenile Hormone Mimic (e.g. Sumilarv)

Other compounds that could be used for mosquito control

  • Temephos OP larvacide (Skeeter Abate, Abate) -Registration Cancelled by EPA.  Can no longer be used (sold) after December 31, 2016.
  • Naled – Dibrom is an Organophosphate insecticide (adulticide).  Naled has a half-loss time on soil in sunlight of about 30 minutes. The label says that it should be applied at night unless a disease pathogen has been detected in the area.  Aerial ULV spray rate is 0.5-1.0 oz./acre.
  • Malathion, Fyfanon is an ULV Organophosphate insecticide (adulticide). The organophosphate insecticides  are used alternately with pyrethroids to control resistance in the mosquito populations  to the pyrethroids.
  • Pyrethroids (Pyrethrum, Resmethrin) are short lived compounds that break down quickly in sunlight.  Persistent pyrethroids like Permethrin are occasionally used but would have a greater effect on foraging honey bees because they persist longer on surfaces.

 

Additional Resources

UF extension documents on mosquito control

Florida Department of Agriculture and Consumer Services -mosquito control

Florida mosquito control directory map

Mosquito species and habitats