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Pests & diseases of Pandanus

July 2003. A request came from Hawaii for information on the pests and diseases of Pandanus spp. A study was being done on the impact of non-native pests on native species of plants and animals in the Pacific islands. On Maui, Hawaii, a scale insect, Thysanococcus pandani Stickney, is attacking Pandanus tectorius. This insect is said to otherwise be known only in Java and Singapore (Hawaii Biological Survey). It was first recorded in Hawaii at Hana, Maui, in 1995 and has spread on Maui, but has not yet reached another island. Is it on other Pacific islands?

NAQS (Northern Australian Quarantine Strategy), Queensland mentioned that a psyllid was causing a decline of Pandanus in southeast Queensland several years’ ago.

Other members from Hawaii mentioned that Thysanococcus pandani has spread from Kahanu Gardens, Hana, westward along the coast. It has not been reported from any of the other major Hawaiian Islands. There is a paper on the halimococcid entitled: The External Anatomy of the Red Date Scale and its Allies. It includes mostly taxonomic information on T pandani, but it mentions other scale insects that may attack Pandanus.

As far as other insects on Pandanus, perhaps the Walkingstick that is found on the Big Island (and now on Maui and Kauai). Necrosia sp., probably fed on Pandanus on the Pacific Islands.

Information was provided from Cook Islands that in the late 1920s most Pandanus tectorius and P spurius was destroyed on Rarotonga by a mealybug. A 1914 report notes Pseudococcus pandani on pandanus on Rarotonga, but all later authors leave the mealybug as unidentified. However, Williams and Watson (CABI publication1988) reported specimens of Laminicoccus pandani on Freycinetia on Rarotonga from 1954.

In the 1980s, large areas of Pandanus tectorius were destroyed on Atiu and Mangaia by a mealybug, and many thought this event was connected to the new pineapple industry and the Pineapple mealybug (Dysmicoccus brevipes). However, entomologists have said that this was not the Pineapple mealybug, although nobody seems to have actually identified what was responsible. Williams and Watson (1988) examined specimens of Laminococcus pandani from Atiu in 1977.

In a summary from the Natural History Museum, London, it was said that Thysanococcus pandani is not a mealybug (family Pseudococcidae), but a member of the scale insect family Halimococcidae. It is native to southern Asia (Singapore and Indonesia) and in the Pacific it has only been recorded (quite recently) from Hawaii (see the latest catalogue entry online at: ).

On the basis of this information, and the knowledge that there are several true mealybug species (Pseudococcidae) in the Pacific region that could damage Pandanus (especially Laminicoccus pandani but also L vitiensis and Leptococcus grallator), there is no reason to believe that T pandani was in Rarotaonga in the early 1900s. It is much more likely that the damage that occurred was due to Laminicoccus pandani (Pseudococcidae).