Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

Natural enemies
4.9
Dysmicoccus brevipes
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A number of coccinellid predators are recorded attacking D. brevipes (Table
4.9.1) and it is possible that some of these have a sufficiently narrow host
range to be considered for introduction. However, it is more likely that the
dipterous and lepidopterous predators will be more specific. The encyrtid
parasitoids would appear to be even more promising and it seems that the full
range of species attacking D. brevipes in Central and South America has not
yet been identified.
Attempts at biological control
HAWAII
A number of natural enemies, mainly encyrtid parasitoids and coccinellid
and dipterous predators have been successfully introduced, in particular into
Hawaii, Puerto Rico and the Philippines (Table 4.9.2). Details are provided
in the country accounts that follow. It will become clear that a substantial
degree of control of D. brevipes can be achieved in the absence of ants,
which clearly protect the mealybugs against parasitoids and predators.
The pineapple mealybug has, for many years, constituted the most serious
insect problem of the pineapple industry (Carter 1932; Beardsley 1959) and
it is also a minor pest of sugarcane and bananas. An encyrtid wasp
Euryrophalus schwarzi (= E. pretiosa)
was reared from D. brevipes
collected from sugarcane (Beardsley 1959).
In the early 1920s several natural enemies were introduced from Mexico
and Panama, but none became established (Rohrbach et al. 1988). Anagyrus
ananatis and Hambletonia pseudococcina from Central America and Brazil
were established in 1935Ð36 and were effective in Maui where the dominant
ant was the crazy ant Paratrechina longicornis.
Parasitisation was high and
pineapple wilt quite severe (Carter 1945). Other introductions known to
have become established are an encyrtid parasitoid ( Euryrhopalus
propinquus),
a cecidomyiid predator ( Vincentodiplosus pseudococci),
and
two less effective coccinellid predators ( Scymnus (= Nephus)
bilucenarius
and Scymnus uncinatus)
(Lai and Funasaki 1986).
Overall, although the biological control of the pineapple mealybug has
not been completely successful, a considerable reduction in abundance has
resulted from the combined action of the cecidomyiid predator
Vincentodiplosis and the encyrtid parasitoids Anagyrus ananatis and
Hambletonia pseudococcina.
They are highly effective only where ants are
adequately controlled (Clausen 1978). Coccinellids are important for short
periods, particularly in the middle of large plantings, where the absence of
ants renders D. brevipes exposed to attack (Carter 1935, 1944).