In 1993 people on the Caribbean
island of Grenada noticed extensive damage to a large number of trees,
shrubs and vegetables, caused by a previously unknown pest—the pink
mealybug (PMB), Maconellicoccus hirsutus. Grenada’s
horticultural production has been badly affected and earlier this year
the mealybug found its way to neighbouring Trinidad. It has now been
confirmed in St. Kitts. Applying selective pesticides and burning
affected material only offers a short-term solution so a sustainable
programme has been launched to introduce natural enemies of the
mealybug from its native range.
Supported by FAO, the International Institute of
Biological Control (IIBC) is collaborating with Caribbean Ministries
of Agriculture to study the mealybug and select promising control
agents. Several species of Anagyrus parasite wasp have proved
effective. In Egypt Anagyrus kamali provides very good control
of the mealybug with para-sitization levels ranging from 66-98%. The
PMB was accidentally introduced into Hawaii in 1983 and has been kept
under natural control by A. kamali and another Anagyrus
species, apparently introduced at the same time as their host. As an
internal parasitoid with a strong preference for mealybugs in general
and the PMB in particular, A. kamali will not pose a risk to
non-target organisms and is the logical choice for the Caribbean.
Live wasps were hand-carried to Grenada in October
1995 and are being multiplied on established mealy bugs in an
insectary. Ministry staff are being trained in rearing methods and
made the first pilot field releases of 1,000 adults in November. The
programme plans to train farmers and agricultural industries to adopt
biological control and reduce their reliance on chemical methods.
For more information contact
Tony Cross at IIBC, Silwood Park, Ascot, Berks SL5 7TA, UK.
[This article first appeared in Pesticides News No. 31,March 1996, page 18]