Agriculture Reference
In-Depth Information
their eggs in the developing fruit as it starts to ripen. Larvae produced by these
eggs feed on the pulp and move through the fruit, causing premature ripening,
rotting and fruit drop. The larvae eventually leave the fruit and bury into the
ground to become pupae; this phase lasts until the adults emerge, and the cycle
is repeated. Control measures include early harvest to shorten exposure time,
eliminating other host plants, collecting and burying fallen fruit, and the use
of traps to monitor adult populations. The release of sterile males can be very
useful in isolated areas or valleys or islands where in-migration of new fl ies is
dii cult. Chemical control based on Malathion and hydrolysed protein bait is
also used. Bagging is used in some countries (Fig. 10.8b); though expensive
it results in fruit without fl y injury, very little or no anthracnose, better colour
and about 95% of the harvested fruit is saleable.
The mango seed weevil has been a major deterrent to mango export
to some countries. The weevil is an Old World pest, but is found now in
some parts of the New World: St Lucia, Guadeloupe and Martinique in the
Caribbean region (Pollard and Alleyne, 1986). Field sanitation, chemical
sprays, host-plant resistance, pest-free zones, fruit culling, using X-ray
technology and irradiation are possible solutions to this problem, unless
markets are found in temperate countries that do not require disinfestation. All
cultivars are susceptible, with some cultivars showing lower seed infestations
of 17% to a high of 86%. The weevil deposits its eggs on the surface in the
sinus region of small green fruit in the lower 2 m of the tree. Upon hatching,
the larva burrows through the soft pulp into the seed, goes through the pupal
stages feeding on the developing seed and then fi nally develops into an adult
weevil. When the fruit ripens and pulp decomposes, the adult beetles bore their
way out of the endocarp and enter diapause in cracks and crevices on the tree
until the next season. Since there is no external evidence of infestation and
the fruit normally remains edible, the consumer is unaware of their presence.
The weevil can af ect the appearance of the fl esh if the mature weevil burrows
out, causing decay, which hastens ripening and may even cause premature
fruit drop.
The mango hopper is a serious pest in India, the Philippines and some
other areas. The hopper sucks the sap from fl owering stems, causing them
to wilt. In serious cases, most of the panicles are damaged. Mango fl owers
are destroyed by four mango blossom midge species and others attack the
leaves (Table 10.6). One of these midges is a serious pest of mango fl owers
throughout the state of Hawaii, with several cultivars having 91% of the buds
infested, leading to perfect-fl ower abortion. Eradication by chemical sprays is
not feasible, due to the wide distribution and the large size of the trees, and
biological control is not an alternative as no predators have been reported in
the native habitats.
In Central America, cutting ants (
Atta
) can be a serious problem,
especially for young plants because they can completely defoliate the tree.
Control can include surrounding plants with an old tyre split in half and
