There are pockets of Pink Hibiscus Mealybug in all districts in Grand Cayman and in Cayman Brac, but so far Little Cayman remains free of the pest.
‘I should point out that in Cayman Brac, the infestation that was found on the western end of the Island has not spread since it was first discovered last October,’ said Plant Protection Officer for the Department of Agriculture Ms Joan Steer.
A Florida laboratory first confirmed the presence of PHM in the Cayman Islands on 21 June, 2006. The preferred host plant of the PHM is the hibiscus, but the insect is known to target many other species of plants and unchecked it can devastate an environment.
A colony of PHM injects toxins into its host plant, which destroys new growth and withers leaves; in some cases it can also eventually kill the plant.
Evidence has shown that PHM has the potential to target over 250 different plants and trees including commercially important species of citrus, coconut, sea grape, mango and okra.
Within a week of the first confirmed case of PHM, DoA enlisted the help of the United States Department of Agriculture’s Biological Control Program and the first batch of predatory ladybird beetles (Cryptolaemus montrouzieri) was released near affected sites in George Town.
These ladybugs eat PHM.
The following month, in July 2006, DoA began going into the infestation zones and releasing batches of a type of parasitic wasp. The wasp works by laying an egg in the mealybug. The egg then hatches and as the larvae grows and feeds, it kills the mealybug host and produces a mummy, from which a new adult wasp emerges.
Ms Steer explained, ‘The wasp is spreading very nicely and wherever new infestations are found the wasp is always present. Earlier when the population of mealybug was high, we were seeing it hopping onto other varieties of plants, but with the control that we are getting now the pest is moving from those other plants and we are seeing it return to its preferred host the hibiscus.’
Studies across the Caribbean have shown that the release of the parasitoid wasps have lead to an over 90 per cent reduction in PHM and are an effective long-term control.
‘We are not releasing bio agents presently because we have thousands of them out there and we are finding them everywhere. Also, if the population of PHM or any other mealy bug becomes high in a particular place, we usually find that the ladybird beetle is moving into those areas.’
‘We are seeing significant improvements in those areas where the insect was first found,’ says Brian Critchlow, public relations spokesperson for DoA. ‘The plants are recovering and we are seeing new flushes of growth. I think overall the programme is achieving the results we hoped for.’
It has now been almost two years since the pest arrived in Grand Cayman and the biological programme was established.
Ms Steer says, ‘It is still early days. We will continue to have flare ups of PHM, but over time, over a period of several years it will continue to get better and better. Right now we are seeing hibiscus plants blooming and that is a clear indication that the problem is improving.’
Related Videos
