The red gum lerp psyllid Glycaspis brimblecombei Moore (Hemiptera: Psyllidae) is a small (2.5 – 3.1 mm) sap-sucking insect that has distinct adult and nymphal stages. The nymph has a flattened body and is covered by a white conical shelter of wax and sugar (the ‘lerp’) and feeds on leaves concealed under this cover. Adults have wings and can disperse widely.
This Australian species is not considered to be a pest at home but it has become a serious pest of eucalypts in many countries where it has been introduced (see distribution).
G. brimblecombei feeds mainly on Eucalyptus spp. in the Section Exsertaria in Australia (e.g. E. camaldulensis, E. tereticornis, E. rudis, E. brassiana, etc.) but it is also found feeding on other taxa outside Australia, including E. urophylla, E. grandis and some hybrids such as E. grandis x E. camaldulensis and E. grandis x E. urophylla.
The pest causes leaf discolouration, severe defoliation, eventually leading to dieback and can significantly reduce tree growth. In some stands of E. camaldulensis in Brazil it was observed to cause 40 to 95 % tree mortality following three consecutive years of infestations.
At present, this pest is distributed in 20 countries over four continents (excluding Asia). In South America, G. brimblecombei spread to ten countries in only eight years after its first detection. It has most recently been found in South Africa (2012).
This insect can be detected and monitored using yellow stick traps placed in eucalyptus trees.
Common native generalist predators of psyllids, such as lady beetles and green lacewings, are not efficient control agents for G. brimblecombei due the protection conferred by the lerp.
The main control strategy is based on biological control using a nymph parasitoid Psyllaephagus bliteus (Hymenoptera: Encyrtidae), which has been introduced into the America’s and Europe.
The BiCEP project aims to improve biological control of this pest by providing parasitoid diversity that may be better matched to different climatic zones. Studies evaluating entomopathogenic fungi are ongoing in Brazil.