Assessing the risks of releasing a sap-sucking lace bug, Gargaphia decoris, against the invasive tree Solanum mauritianum in New Zealand

Abstract

The South American tree Solanum mauritianum Scopoli (Solanaceae), a major environmental weed in South Africa and New Zealand, has been targeted for biological control, with releases of agents restricted to South Africa. The leaf-sucking lace bug, Gargaphia decoris Drake (Tingidae), so far the only agent released, has become established in South Africa with recent reports of severe damage at a few field sites. To evaluate the insect's suitability for release in New Zealand, host-specificity testing was carried out in South Africa in laboratory and open-field trials, with selected cultivated and native species of Solanum from New Zealand. No-choice tests confirmed the results of earlier trials that none of the three native New Zealand Solanum species are acceptable as hosts. Although the cultivated Solanum muricatum Aiton and S. quitoense Lam. also proved unacceptable as hosts, some cultivars of S. melongena L. (eggplant) supported feeding, development and oviposition in the no-choice tests. Although eggplant was routinely accepted under laboratory no-choice conditions in this and previous studies, observations in the native and introduced range of G. decoris, open-field trials and risk assessment based on multiple measures of insect performance indicate that the insect has a host range restricted to S. mauritianum. These results strongly support the proposed release of G. decoris in New Zealand because risks to non-target native and cultivated Solanum species appear to be negligible. An application for permission to release G. decoris in New Zealand will be submitted to the regulatory authority.

Biology ofLeptoypha hospita(Hemiptera: Tingidae), a Potential Biological Control Agent of Chinese Privet

“…It has become established in South Africa with reports of severe damage to S. mauritianum at a few Þeld sites. Based on its excellent performance in South Africa, an application for permission to release G. decoris in New Zealand will be submitted to the regulatory authority (Olckers and Borea 2009).…”

The identification and remote detection of alien invasive plants in commercial forests: An Overview

“…The introduction of several chemical and mechanical control methods has also experienced difficulties owing to the expenses associated with such techniques and the spatial extent of infestations. Although biological control programs such as using natural enemies to control the spread of weeds has shown the most potential, to date, their overall impact on controlling IAPs remains insufficient (Olckers and Borea, 2009). …”

“…1), has become one of the most notorious alien invasive plant species to affect southern Africa (Olckers and Borea, 2009). It is recognised as one of the sixth most aggressive, opportunistic and extremely resilient plant invaders in the region.…”

“…Bugweed is an evergreen, noxious, branched shrub, varying between 2 m to 10 m in height with grey-green oval shaped leaves. The plant has a lifespan of up to thirty years and is a major constituent of agricultural land, forestry plantations, water courses and disturbed environments (Copeland andWharton, 2006, Olckers andBorea, 2009). Bugweed has earned a classification of a category one 'transformer' weed (Jordaan and Downs, 2012) indicating that extensive stands are able to dominate and replace canopy or subcanopy layers of forest ecosystems (Witkowski andGarner, 2008, Olckers, 2011).…”

Gargaphia decoris(Hemiptera: Tingidae) from Two South American Provenances are Equally Safe for Release Against the Invasive Tree,Solanum mauritianum(Solanaceae)

“…The plant has also emerged as a weed of similar situations in Australia (Florentine et al 2003;ISSG 2006) and New Zealand (Atkinson 1997;McGregor 1999;ISSG 2006). Biological control was implemented in South Africa to augment integrated control operations (Olckers 1999(Olckers , 2009) and is pending implementation in New Zealand (Withers et al 2002;Olckers & Borea 2009). …”