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HISPID BEETLE Promecotheca cumingi Baly -- Coleoptera, Hispidae (Contacts) ----- CLICK on Photo to enlarge &
search for Subject Matter with Ctrl/F. GO TO ALL: Bio-Control Cases In
a separate project the coconut leaf-mining beetle was accidentally introduced
into Sri Lanka where it was discovered in 1970 beginning to develop into a
devastating pest of coconuts (Simmonds 1976). In March, 1971, the Commonwealth Institute of Biological
Control was asked to advise on the possibilities of biological control, and
in view of the very successful control of P.
reichei Baly in Fiji in 1937
(Taylor 1937), it was suggested that Pediobius
parvulus (Férrière) and Dimmockia javan Férrière be tried.
In Fiji both of these parasitoids had been introduced, but Pediobius only was extremely
successful (by 1971, 35 years later, the former pest was difficult to find in
Fiji and naturally its parasite also.
Dimmockia javan following introduction
died out. In Sri Lanka there was no
reason to believe that the same pattern would not occur, but both Pediobius and Dimmockia were liberated in
large numbers. It soon became apparent,
however, that in Sri Lanka Dimmockia
was to become the dominant parasitoid, with Pediobius apparently becoming established but extremely
rare. Successful biological control
of Promecotheca was obtained
from this effort (Fernando 1972). Simmonds
(1976) suggests that in this example there was a complete reversal of roles
played by the two parasitoids in controlling Promecotheca in Sri Lanka and Fiji, although the ultimate
practical result was the same. Had
detailed ecological investigation preceded parasitoid introduction it is
possible that a consideration of details of climatic preferences,
host-preferences, life-cycle, etc. of both hosts and parasitoids might have
indicated the usefulness in Sri Lanka of Dimmockia
rather than Pediobius. But, this is by no means certain. What is certain is that such a detailed
study would have deferred the ultimate successful biological control of Promecotheca by more than a
year at least, during which time the increase of the pest and subsequent
losses from chemical control, etc. would have been considerable, and it would
have taken a longer time, with consequent increases losses, to effect
biological control and complete recovery of the palms (Simmonds 1976). Although it might be argued that the introduction
of natural enemies in this manner is scientifically unacceptable, it must be
born in mind that the ultimate unpredictability of the result of such
introductions should be left to the natural enemies themselves to determine
which is more suited to a new environment (Simmonds 1976). REFERENCES: [Additional references may be
found at: MELVYL
Library ] Fernando,
H. E. 1972. The coconut leaf
beetle Promecotheca cumingi and its control. Coconut Planters Rev. 6: 152-56. Simmonds, F. J. 1972. Approaches to
biological control problems. Entomophaga
17: 251-. Taylor, T.
H. C. 1973. The biological
control of an insect in Fiji. An
account of the coconut leaf-mining beetle and its parasite complex. Imperial Inst. Ent., London. 239 p. Simmonds, F. J. 1976. Some recent
puzzles in biological control.
Entomophaga 21: 327-32. |
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