Repellent testing: efficacy of methiocarb for protecting sorghum from
house sparrow damage

Prior work by DWRC staff indicates that chemical repellents and
frightening agents offer a promising strategy for reducing quelea
damage to African grain crops. Methiocarb is one of these chemicals.
It is widely used as a bird repellent in the U. S. and has been
registered for several crop applications. In laboratory tests, quelea
were found to be six times more sensitive to methiocarb than red-
winged blackbirds.

Cage tests conducted in Sudan during 1977 (see 1977 Annual Report)
showed that good protection could be achieved by applying methiocarb
to sorghum with a hand sprayer. Additional testing is necessary but
fieldwork in Sudan is hindered by factors such as weather, logistics,
and seasonal movements of the quelea population. To overcome some of
these hindrances, interim field testing will be done in the U. S.
These trials were initiated in July, at the Texas A&M Agricultural
Experiment Station, Weslaco, Texas. A variety of sorghum (TX 623),
which is comparable to the Daber variety common in Sudan, was heavily
damaged in 1976 by house sparrows (same family as quelea).

The bird damage situation at Weslaco was believed to be similar enough
to Sudan situations that information of importance to future field
testing in Sudan could be obtained relatively easily. The most impor-
tant data sought were: (1) the optimum concentration of methiocarb to
apply to the sorghum heads, and (2) the optimum concentration of adhe-
sive to use in combination with the repellent.

Three caged test plots were established and treated as follows: (1)
reference (no treatment), (2) hand-sprayed methiocarb at 3 Ib/acre,
and (3) hand-sprayed methiocarb:adhesive at 3:1 Ib/acre. House spar-
rows were introduced into each caged test plot along with alternate
food and water.

After 120 bird days of exposure, damage to the untreated (reference)
plot was about 27 percent. Damage to the methiocarb:adhesive-treated
plot was about 18 percent and the methiocarb-treated plot was evi-
dently not damaged. The apparent relative effectiveness of each
treatment was confirmed by direct observation of bird activity. Birds
in the untreated test cage began to feed on sorghum heads immediately
and did not disturb the alternate food available to them. In con-
trast, birds in the methiocarb (no adhesive) cage spent little time on
the sorghum heads and consumed or spilled much of their alternate
food. Some feeding on heads was observed in the methiocarb:adhesive
plot.