Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

296 Biological Control of Insect Pests: Southeast Asian Prospects
The citrus mealybug is also attacked in most regions by encyrtid and
sometimes by platygasterid parasitoids (Table 4.15.2), several of which are
capable of having a significant effect in warm climates. If the origin of
P. citri is really China, it is surprising that there are not reports of a number
of specific or near specific parasitoids from that region. Indeed the species
most commonly employed for biological control is Leptomastix dactylopii
which is believed to be native to Brazil.
A few fungi attack P. citri under humid conditions (Table 4.15.3).
Attempts at biological control
Any account of the biological control of P. citri is complicated by the facts that
(i) it has been confused with other species on a number of occasions, so that
early records are often unreliable, (ii) documentation of some introductions is
poor or lacking, and (iii) natural enemies (that also attack it) have often been
introduced in programs aimed at other mealybugs. Table 4.15.4 summarises
the main introductions for biological control of P. citri.
CALIFORNIA
It is convenient to outline, first, the prolonged attempts against P. citri in
California, since programs elsewhere almost always draw extensively on
experience there. Furthermore, since the first introduction of Cryptolaemus
montrouzieri from Australia to California in 1891Ð92, there have been few
parasites or predators used in the control of any economically important
mealybug anywhere in the world that have not also been tested against
P. citri in California, in the hope that they might attack it also (Bartlett
1978).
C. montrouzieri was mass reared and released in California against
P. citri with some success, but repeated releases were required to achieve
satisfactory control. Another coccinellid Nephus (= Scymnus) bipunctatus
(under the name of Cryptogonus orbiculus) was introduced in 1910 from the
Philippines, but did not become established (Bartlett 1978). However,
establishment followed the introduction from Sicily in 1914 of the parasitoid
Leptomastidea abnormis, although control was only partly successful
(Viereck 1915; Smith 1917). The coccinellid Scymnus binaevatus from
South Africa was established in 1921, but persists only in small numbers.
Unsuccessful attempts were made to establish the encyrtid
Coccidoxenoides peregrinus from Hawaii where it was having a major
impact on P. citri, misidentified at the time as Planococcus kraunhiae.
However, progeny of a single female from South China in 1950 allowed the
species to become established, although at a low level (Flanders 1957).