Natural enemies may provide the solution to the giant whitefly problem |28 January 2008

In many places food plants can no longer be grown due to the effects of the whitefly and fruits are damaged, sometimes becoming inedible.  This problem affects many other countries and is a significant economic problem for areas with important fruit growing industries.

In places such as California much effort and expense has been invested in trying to find solutions to the problem.  Chemical control has been unsuccessful but there have been some limited successes with biological control through introducing parasites or encouraging the natural enemies of the whiteflies.

In Seychelles the giant whiteflies have spread unchecked, with few agricultural or garden plants immune from attack.  In December a large increase in lace-wings was noticed on Silhouette.  Further investigation by Nature Protection Trust of Seychelles found that the lace-wings were laying their eggs among the whiteflies.  Lace-wing larvae are voracious predators and will consume many small insects every day.  The whiteflies are also attracting large numbers of ladybird Chilocorus nigritis.  This species was introduced in the 1950s to attack scale insects, but is now turning its attention to whiteflies.  An unidentified predatory bug has also been found feeding on the whitefly.

It seems that after an initial delay, the predatory insects of Seychelles are starting to use the giant whitefly as a food resource.  It is to be hoped that they will soon bring it under control without the need for any new introductions or pesticide treatments.  These predators may also attack the rapidly spreading coconut whitefly, although there is no evidence of this so far.
 
   Contributed by Nature Protection Trust of Seychelles