Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

ISRAEL
4.15 Planococcus citri 303
Releases of Cryptolaemus montrouzieri on a coffee estate in Kerala
virtually eliminated P. citri, but the coccinellid could not be found thereafter
for some 6 months, when it reappeared about 10 km distant and virtually
eliminated mealybugs from an infestation (Chacko et al. 1978). The
requirement that each female consume at least 8 P. citri for normal egg
production (192 eggs/female) was suggested as the reason for the poor
establishment of C. montrouzieri when only low populations of P. citri are
available (Reddy et al. 1991).
The citrus mealybug is a serious pest of citrus and ornamentals of tropical
origin. It develops on the fruit and roots of young trees, the main damage
being caused by individuals settling beneath the sepals of citrus fruit and
injuring the fruit: honeydew produced also attracts fruit-piercing moths
(Mendel et al. 1992).
Two native encyrtids, Anagyrus pseudococci and Leptomastidea
abnormis, attack P. citri which is, nevertheless, an important pest of citrus
and some other crops (Rosen and Ršssler 1966).
Unsuccessful attempts were made to establish Cryptolaemus
montrouzieri in 1924 from Egypt (Bodenheimer and Guttfeld 1929; Mason
1941) and 1958 (Rosen 1967a), but a Spanish strain introduced in the 1980s
finally established (Mendel et al. 1992). Leptomastix dactylopii imported
from Canada in 1941 was only briefly established (Rivnay 1960). Clausenia
purpurea, a parasitoid of Pseudococcus citriculus introduced from Japan in
1940, attacks P. citri, but has little effect on its density (Rosen 1964).
P. citrus became a serious pest on recently established grapefruit in
southern Negev. The encyrtid Anagyrus pseudococci was present in very
low numbers and Chrysoperla carnea was active, but only in spring. The
coccinellid Chilocorus bipustulatus was more abundant and was considered
to have potential as a biological control agent (Berlinger et al. 1979). Seven
parasitoids and 10 predators have been recorded, of which Anagyrus
pseudococci (Encyrtidae) and Sympherobius sanctus (Chrysopidae) were
found in significant numbers by Mendel et al. (1992). However,
development of A. pseudococci is restricted by winter temperatures. Its
development threshold is 13¡C and no eggs are laid below 15¡C, whereas
P. citri still lays eggs at 13¡C and its development threshold is 8.4¡C. By the
time in late spring when the population of A. pseudococci starts to built up,
P. citri has already settled under the sepals, where it is well protected from
the parasitoid. Climatic conditions were thus regarded as unfavourable for
existing natural enemies (Mendel et al. 1992).