Mango gall midges on Australia's doorstep

Gall midges (Diptera: Cecidomyiidae) are common pests of mango trees in southern Asia. Currently, there are 21 described species from six genera and at least 10 undescribed species which are known to attack mango worldwide. All of the six described species known to attack mango in Southeast Asia and Australasia belong to the genus Procontarinia. Most mango gall midges cause leaf galls but some cause flower damage, others damage branches and shoots and one species attacks fruit. Few studies have quantified the economic impact of any of these species but considerable damage to leaves is commonly observed and, similar to direct damage by flower- and fruit-infesting species, is likely to affect fruit production. Studies of mango midges are hampered by difficulties in associating infestation symptoms with a particular species but techniques developed recently, such as gall histology and DNA barcoding, provide a means of accurately identifying known species without relying on rearing adults from galls. Surveys of mango trees in Australia, Cambodia, Myanmar, the Philippines, Timor-Leste, Solomon Islands and Papua New Guinea revealed the presence of eight species of gall midge, four of which appear to be new to science: Procontarinia sp. causing “high doughnut” leaf gall in Timor-Leste, Procontarinia sp. causing “low doughnut” leaf gall in Timor-Leste, Procontarinia sp. causing “blister” leaf gall in Timor-Leste and Cecidomyiidae sp. causing spherical leaf gall in Cambodia. Only a single species, Procontarinia pustulata, was present in Australia, having recently arrived onto Cape York Peninsula from Papua New Guinea via the Torres Strait. Furthermore, one of the undescribed species was detected recently near the Papua New Guinea/Indonesian border, indicating the possible presence of a pathway for the movement of midges from Asia into Australasia and continuing into Australia. The presence of a species on the Solomon Islands lends further support for an active pathway into Australasia. Procontarina echinogalliperda is reported for the first time from Myanmar. P. pustulata is reported for the first time from Timor-Leste and the Philippines and Procontarinia mangicola is reported for the first time from the Solomon Islands.