Review of the successful classical biological control programs in Sultanate of Oman.
The history of the classical biological control against insect pests in Oman is not yet properly documented. During the last 23 years there were many successful classical biological control programs conducted in Oman. These programs were designed and applied against many serious insect pests in both, outdoor crops, fruit trees (Omani lime, coconut, guava, caster apple, avocado and pomegranate) and greenhouse crops (cucumber, tomato, sweet pepper and lettuce). This paper is reviewing the successful classical biological control programs which were implemented in Oman during the period from 1984 to 2007. The first project was conducted in 1984 by releasing the parasitic wasp, Encarsia opulenta Silvestri. against the Citrus Black Fly, Aleurocanthus woglaumi Ashby. In 1985, the second successful biological control project was applied using the coccinellid predatory beetle. Chilocorus nigritus (Fabricius), to control the coconut scale insect. Aspidiotus destructor Sign. In 1989, very important project was successfully applied to control the coconut rhinoceros beetle. Oryctes rhinoceros L., by using the specific virus. Rhabdionvirus oryctes Hüger. In 1994, the mealybug destroyer. Crytolaemus montrouzieri Mulsant. was used successfully to control the citrus mealybug, Planococcus citri (Risso), and the Pink Hibiscus Mealybug, Maconellicoccus hirsutus (Green). In 2002, three natural enemies were imported and released to control the two common aphids' species in Jabal Akhdar, the pomegranate aphid, Aphis punicae (Passerini), on pomegranate and the melon aphid, Aphis gossypii (Glover), on different fruit trees such as: pomegranate, apple and pear. These three natural enemies were the convergent lady beetle, Hippodamia convergens Guérin-Méneville (about 200 thousands beetles were released), the parasitic wasp. Aphidius colemanii Viereck (about 5 thousands adults were released) and the multicolored Asian lady beetle, Harmonia axyridis Pallas (about 37,500 thousands beetles were released). From 2003, biological control of the pomegranate butterfly, Virachola livia Klug, which is the most destructive insect pest attacking pomegranate in Jabal Akhdar was successfully achieved by seasonally releases of the egg parasitic wasps, Trichogramma spp. On the other hand, from 1994 till 2007, a number of the common greenhouse pests such as: thrips, whiteflies, mites and leaf-miners were successfully controlled in Royal Gardens and Farms in Oman, by using different bio-agents. i.e., the predatory mites, Amblyseius cucumeris, A. swirskii and Phytoseiulus persimilus, the predatory bugs, Orius laevigatus and Macrolophus caliginosus and mixture of the parasitic wasps, Dacnusa sibirica and Diglyphus isaea.