EFFECT OF ETHERIC ACORUS-CALAMUS OIL AND BETA-ASARONE ON THE LARGER CORN-BORER PROSTEPHANUS-TRUNCATUS (HORN) (COL BOSTRICHIDAE)

In the early 1980s, Prostephanus truncatus (Horn) spread out uncontrollably in areas south of the Sahara, having been brought in by imported maize from tropical regions of America. Its main diet is maize; it reproduces at a great rate in stored maize cobs. Attempts were made to control this pest using Acorus calamus oil and its main ingredient beta-asarone, as the use of similar oils has been shown to arrest the development of other insects. Vapourising the maize kernels and cobs was unsuccessful and in some cases led to a significant increase in the destruction of maize and the reproduction of beetles. However vapourisation killed hungry beetles within 3 days; short periods of treatment achieved a high rate of pest destruction, leaving the survivors with a reduced appetite and reproductive rate. Spraying of maize cobs did not prevent infestation; beetles able to infect these cobs reproduced normally. Success was only achieved by spraying maize kernels, using Acorus calamus oil dosed at 750 mg per kilo maize; damage was then restricted to 5 %.