Dengue is the most important mosquito-borne viral disease. No specific treatment or vaccine is currently available;
traditional vector control methods can rarely achieve adequate control. Recently, the RIDL (Release of Insect carrying
Dominant Lethality) approach has been developed, based on the sterile insect technique, in which genetically engineered
‘sterile’ homozygous RIDL male insects are released to mate wild females; the offspring inherit a copy of the RIDL construct
and die. A RIDL strain of the dengue mosquito,
Aedes aegypti
, OX513A, expresses a fluorescent marker gene for
identification (DsRed2) and a protein (tTAV) that causes the offspring to die. We examined whether these proteins could
adversely affect predators that may feed on the insect.
Aedes aegypti
is a peri-domestic mosquito that typically breeds in
small, rain-water-filled containers and has no specific predators.
Toxorhynchites
larvae feed on small aquatic organisms and
are easily reared in the laboratory where they can be fed exclusively on mosquito larvae. To evaluate the effect of a predator
feeding on a diet of RIDL insects, OX513A
Ae. aegypti
larvae were fed to two different species of
Toxorhynchites
(
Tx.
splendens
and
Tx. amboinensis
) and effects on life table parameters of all life stages were compared to being fed on wild
type larvae. No significant negative effect was observed on any life table parameter studied; this outcome and the benign
nature of the expressed proteins (tTAV and DsRed2) indicate that
Ae. aegypti
OX513A RIDL strain is unlikely to have any
adverse effects on predators in the environment.