Mealybugs: banana fruit & rambutan Minimize

October 2000. Samoa has a protocol in place for the export of bananas to New Zealand; under this, it is recognised that bananas are a non-fruit fly host. However, mealybugs have proved to be a major quarantine constraint for exports and because of this, information on pre- and post-harvest control was required. However, the recommendations must comply with organic certification.

The request also mentioned control of mealybugs in rambutan, 'organic' as well as conventional methods.

A similar problem was experienced by a PestNet member some years ago in the Philippines, and the problem was solved quite simply: during the process of cooling the banana hands by immersing them in water, and subsequently separating them, a water jet under high pressure was used to wash away the mealybugs. The water jet was easily manufactured: it consisted of a small pipe attached to a hose from an electric water pump, using the water of the wash tank. The person operating the hose must be properly chlothed to avoid continuous exposure to water spray.

It was also pointed out that mealybug control begins with ant control. Also, any control strategy should include wasp parasitoids and Cryptolaemus coccinellids (www.bugsforbugs.com.au/product/32). The latter are commercially available from Dan Papacek at Bugs for Bugs. Oils (light mineral) used as undertree sprays for disease control also helps to reduce mealybugs.

In a later post, it was pointed out that sooty mould develops on the sugary honeydew excreted by mealybugs, so a simple cold water jet should be sufficient to dislodge and wash it off.

As for rambutans, again good ant control helps. Trunk application of insecticides is effective and sticky bands can also be tried, but they must be placed on tape, not directly onto bark as it can be phytotoxic. Organic insecticides, such as natural pyrethrum, could be used for ant control. For nonorganic control, chlorpyrifos is effective. With rambutans, avoid any contact between the foliage and the ground; this will help reduce the ant/mealybug problem. It is no good applying ant control measures to the base of trunks if there are lots of other 'ladders' into the tree canopy such as long grass or drooping branches for the ants to climb.

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