Pest Management in Miombo Fruit Trees - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 377

defoliate Uapaca kirkiana trees in parts of Malawi (Meke, 1998) while those of
Argema mimosae cause substantial defoliation of Sclerocarya birrea , which can
reduce growth and fruit production (Van Den Berg, 1990). In the miombo
woodlands of northern Zambia, caterpillars of the emperor moths Gynanisa maja
and Gonimbrasia zambesina defoliate Uapaca kirkiana , U. banguelensis , U.
sansibarica , Anisophyllea boehmii , Parinari curatellifolia and Syzygium guineense
(Mbata et al ., 2002), though their main hosts are the Julbernardia species.
Larvae of Imbrasia belina are known to defoliate Diospyros mespiliformis and
Sclerocarya birrea (Parker, 1978; Mughogo and Munthali, 1995), though its
preferred host is Colophospermum mopane . Several species of Deudorix
defoliate Parinari curatellifolia (Kroon, 1999). Damage by adult beetles and their
larvae is also widespread. For instance, the leaf beetle Mycrosyagrus rosae and
scarab beetles ( Euphoresia sp.) commonly defoliate Uapaca kirkiana in Zambia.
A mosaic of holed leaves, often showing 10-20% defoliation and occasionally up
to 50%, can be observed on U. kirkiana trees. However, by virtue of continued
foliar production through most of the year, U. kirkiana trees are remarkably
resilient to the effects of their defoliators (Parker, 1978).
A significant problem of crown dieback is associated with shoot-boring
Lepidoptera and Coleoptera, especially Curculionidae, Scolytidae and
Cerambycidae. The timber borer Euryops burgeoni has been recorded as a
pest of Parinari species in forests of eastern and central Africa. In Zambia it
burrows into a root of a living healthy tree, but apparently it is not yet a serious
problem (Parker, 1978). As often happens with tropical trees, any basal
damage to the trunk invites termite damage to the wood, which, together with
the activities of decay fungi, is likely to produce a hollow core in the butt.
Among insects with sucking mouth parts, the plant bugs, scale insects and
mealybugs commonly attack the leaves, shoots or branches of fruit trees. Many
of the plant bugs may not cause serious damage other than limited necrosis at
the sites where they feed, caused by toxic saliva. Sap-sucking by adults and
nymphs of the coreid bug Leptoglossus membranaceus can cause wilting of
branches in Uapaca kirkiana (Meke, 1998). Scale insects commonly infest leaves
and shoots throughout the year. On U. kirkiana , Ledaspis sp. and Ceroplastes
uapacae are abundant in Zambia and Malawi (Parker, 1978; G. Meke,
unpublished results; G. Sileshi, unpublished results). Ceroplastes uapacae sucks
sap from the lower surface of the leaf but also causes chlorotic flecks on the
upper surface, and thus may be a virus transmitter.
Mammals
Wild and domestic animals cause damage by browsing and trampling. This is
critical during the juvenile phase of fruit trees. In the eastern province of
Zambia, mortality of Sclerocarya birrea seedlings planted on farmers' fields was
high as a result of browsing by goats (A. Mkonda, personal communications).
In the wild, elephants, eland and zebra are the main browsers of Uapaca
kirkiana (Shorter, 1989). Though elephants have been widely reported as
browsing and damaging S. birrea , their impact has been described as negligible
(Hall et al ., 2002).