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Whitefly, papaya

March 2005. A Spiralling whitefly outbreak was reported on papaya in Samoa. It was said to be Aleurodicus dispersus, but as Bemisia tobaci strain B is present, it is important to have a correct identification. Later, the same problem of whitefly was reported on cucmbers and tomatoes.

The Spiraling whitefly (Aleurodicus dispersus) is quite common in Samoa on guavas, palms, ground orchids, and poinsettias (ornamental). Also, Waterhouse & Norris (Biological Control, Pacific Prospects, 1989) and Dr Paul De Barro and others (Survey of Bemisia tabaci biotype B whitefly and its natural enemies in the South Pacific – CSIRO project report, 1997) have reported this insect present in Samoa. However, although poinsettias are completely defoliated by it, the general impression is that it is presently not a big problem on other plants.

Successful biological control has been reported in many countries (Waterhouse & Norris – Biological control, Pacific Prospects, 1989). Chemical control with synthetic insecticides (which is generally not recommended) and even dilute soap solutions have been reported as effective for short-term treatments. See CABI’s Crop Protection Compendium for further information on this insect and its management.

Other home-made remedies were suggested: a) use yellow (but not too bright) painted tins placed on a stick. Coat the tins once in 3 days with castor oil – about 15 tins per acre are sufficient; b) spraying with water mixed with a little soap (liquid) can be tried. Samoa also reported that spraying with a soap solution was effective on the cucumbers and tomatoes after 2 days.

The Federated States of Micronesia said that If Encarsia ?hatiensis is present it can be seen with the naked eye or by using a magnifying lens. E ?haitiensis are yellow to orange and if they are present they will be seen together with the whiteflies or on the whitefly eggs. It should be possible to see the pupae turning black. Collect these pupae and rear them out in the lab.

In FSM, the spiralling whitefly is mainly a problem on Guava. Once, there was a spiralling whitefly outbreak on another Island (Kosrae) and on many different crops, including bananas, but after the introduction of E ?haitiensis, the whiteflies disappeared. At present in the FSM, there is a problem with Aleurotrachelus trachoides on hot pepper, kava and ornamentals.

It was reported that the Spiralling whitefly gained entry into india in the 90s. It has reached Andaman and Nicobar Islands 1200 km from the mainland and has devastated crops, in particular guava.