A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the academic requirements for the degree of Doctor of Philosophy School of Animal, Plant and Environmental Sciences. Johannesburg, June 2018. / Lantana camara L. (sensu lato) (Verbenaceae) remains one of the worst invasive alien plants in most tropical and subtropical parts of the world, including South Africa. Despite a concerted biological control (biocontrol) effort, with 45 biocontrol agents released against the weed worldwide since the early 1900s to date, L. camara control is far from satisfactory in most areas, including the study area. In 2012, during the initial stage of this work, a plant-ecological survey was conducted in riparian areas along the Sabie River, across an altitudinal gradient, and also in the adjacent forest plantation areas, in the province of Mpumalanga (South Africa). As a follow-up to two separate previous studies in the same area (1996/7 and 2005), aimed at determining the effectiveness of the ‘Working for Water’s (WfW) invasive alien plant (IAP) control programme, this work is another milestone in a long-term monitoring study. However, despite 16 years (1996/7-2012) of integrated IAP-control operations in the area, the WfW programme was only able to successfully remove larger overstorey IAPs, which opened-up the canopy and reduced competition, creating a conducive growing environment for an amalgamation of understorey IAPs, including L. camara, whose spread and densification were still on the rise. Biocontrol is regarded as a better alternative for long-term, sustainable and environmentally friendly IAP control, compared to the conventional mechanical and chemical methods. Most L. camara biocontrol agents introduced into South Africa have not yet had their full impact quantified under field conditions. This work is novel in that, for the first time, it quantifies the combined impact of the ‘old plus new’ suite of L. camara biocontrol agents, on the growth, reproduction and biomass of the weed under field conditions, in an inland area, through an insecticidal exclusion experiment, using carbofuran. Five prominent biocontrol agents occur on L. camara at the study sites, namely the fruit-mining fly, Ophiomyia lantanae (Froggatt) (Diptera: Agromyzidae); the shoot-sucking bug, Teleonemia scrupulosa Stål (Hemiptera: Tingidae); the defoliating moth, Hypena laceratalis Walker (Lepidoptera: Noctuidae); the leaf-mining beetle, Octotoma scabripennis Guèrin-Mèneville (Coleoptera: Chrysomelidae); and the fungal leaf-spot pathogen, cf. Passalora sp. (Chupp) U. Braun & Crous var. lantanae. During the course of this study, an additional agent, the flower-galling mite, Aceria lantanae (Cook) (Acari: Trombidiformes: Eriophyidae), was released and successfully established at lower altitudes (~843 m), showing an affinity for the dark-pink L. camara variety over others in the study area, namely light-pink and red-orange. Agent impact was difficult to measure because the activity of carbofuran in exclusion plants (carbofuran-treated L. camara plants) was short-lived; and therefore the impact of biocontrol agents on L. camara, which appeared to be negligible, may have been underestimated. Despite failing to maintain the ‘exclusion’ plants biocontrol agent-free through the application of carbofuran, there were reductions of 28% in the number of side-stems per plant, 31% fewer seeds in the soil seedbank, and 29% lower seed production, in ‘biocontrol’ plants compared to ‘exclusion’ plants. Although these differences were not statistically significant, they suggest that the present suite of biocontrol agents slightly reduces the vegetative and reproductive growth of L. camara. To achieve significant biocontrol of L. camara in inland areas, it seems necessary to introduce additional agents, which are well adapted to inland climatic conditions. The effects of micro-environmental factors, namely altitude and the degree of shading, were also investigated. Some biocontrol agents, such as T. scrupulosa, exhibited feeding phenological plasticity, resulting in it maintaining its presence at different altitudinal levels throughout the seasons. The performance of the suite of biocontrol agents, except A. lantanae, was, also, not limited by plant varietal differences. Additional research on biological and integrated control of L. camara is required. Keywords: Biocontrol; Biological invasion; Carbofuran; Insecticidal exclusion; Invasive alien plants; Lantana camara; Post-release evaluation. / LG2018

Lantana camara Linnaeus (Verbenaceae), commonly known as lantana, is a highly invasive weed in many parts of the world. In South Africa it is naturalized in several provinces where it invades pastures, riverbanks, mountain slopes and valleys and commercial and natural forests, forming dense, impenetrable thickets. Chemical and mechanical control methods are expensive, labour intensive and provide only temporary relief as cleared areas are rapidly reinfested by seedlings and coppice growth. A biological control programme was initiated in South Africa in the 1960s, but despite the establishment of 11 agent species, it was considered to have had limited success. Several factors are thought to restrict the impact of the biocontrol agents. Firstly, L. camara occurs in a range of climatic regions, some of which are unsuitable for the establishment of agent species of tropical and subtropical origin. Secondly, L. camara is the result of hybridization between several Lantana species, forming a complex of hybridized and hybridizing varieties in the field, which match none of the Lantana species in the region of origin. This causes partial insect-host incompatibility, displayed as varietal preference. Thirdly, parasitism appears to have significantly reduced the effectiveness of several natural enemies. In spite of all these constraints, biological control has reduced invasion by L. camara by 26%. However, the weed is still very damaging and additional natural enemies are required to reduce infestations further. A flea-beetle species, Alagoasa extrema Jacoby (Coleoptera: Chrysomelidae), was collected from several sites in the humid subtropical and tropical regions of Mexico, and imported into quarantine in South Africa and studied as a potential biocontrol agent for L. camara. Favourable biological characteristics of this beetle included long-lived adults, several overlapping generations per year, and high adult and larval feeding rates. Observations from the insect’s native range and studies in South Africa suggest that A. extrema would probably be more suited to the subtropical, rather than the temperate areas in South Africa. Laboratory impact studies indicated that feeding damage by A. extrema larvae, over a period spanning the larval stage (16 to 20 days), reduced the above-ground biomass of L. camara plants by up to 29%. Higher larval populations resulted in a higher reduction of biomass. Varietal preference and suitability studies indicated that A. extrema exhibits a degree of varietal preference under laboratory conditions, with one of the white pink L. camara varieties proving the most suitable host. This variety is one of the most damaging varieties in South Africa and is particularly widespread in Mpumalanga Province. Although A. extrema proved to be damaging to L. camara, laboratory host range trials showed it to be an oligophagous species, capable of feeding and developing on several non-target species, especially two native Lippia species (Verbenaceae). The host suitability of these species was marginally lower than that of L. camara and the potential risk to these indigenous species was deemed to be too high to warrant release. It was therefore recommended that A. extrema not be considered for release in South Africa.

Orientadores: Pedro Luiz Rosalen, Francisco Carlos Groppo / Texto em português e inglês / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-24T17:13:51Z (GMT). No. of bitstreams: 1 Berto_LucianaAranha_D.pdf: 2510809 bytes, checksum: 95557f04245ce04cb76a352459b80504 (MD5) Previous issue date: 2014 / Resumo: Apesar do constante desenvolvimento do conhecimento, prevenção e tratamento da cárie dental, esta doença continua tendo alta prevalência no Brasil e no mundo. Por este motivo, tem crescido o interesse por novos agentes farmacológicos que possam auxiliar no controle do biofilme dental, atuando contra o principal microrganismo associado ao desenvolvimento da cárie, o Streptococcus mutans. Desta forma, o objetivo deste trabalho foi avaliar a atividade antimicrobiana do extrato de quatro plantas do cerrado brasileiro (e suas frações) contra S. mutans UA159. Extratos hidroalcoólicos de Lantana camara (Lc), Copaifera langsdorffii (Cl), Psidium guajava (Pg) e Cochlospermum regium (Cr), foram submetidos a testes de avaliação da atividade antimicrobiana para determinação das concentrações inibitória (CIM) e bactericida (CBM) mínima, inibição da aderência e queda de pH em solução. O extrato bruto das quatro plantas apresentaram potencial antimicrobiano e foram fracionados por gradiente de polaridade, sendo obtidas, para cada extrato, as frações hexânica (FHx), clorofórmica (FCh), acetato de etila (FAc) e aquosa (FAq). Estas foram submetidas aos experimentos já citados para determinação da(s) fração(ões) ativa(s) de cada extrato, selecionadas com base nos resultados dos testes de atividade antimicrobiana e no rendimento. Foram selecionadas, para a etapa subsequente de avaliação em biofilme, 6 frações ativas: Lc-FHx e Lc-FCl, ambas com CIM = 15,6 µg/ml, e rendimento 9,5 e 17,5%, respectivamente; Cl-FHx, que apresentou CIM = 15,6 µg/ml, atividade inibitória sobre a queda de pH em solução e rendimento igual a 21%; Pg-FHx, com CIM = 125 µg/ml, 93,4% de inibição da aderência na concentração de 62,5 µg/ml e rendimento igual a 2,0%; Cr-FHx, com CIM = 125 µg/ml, apresentou atividade inibitória sobre queda de pH do meio e rendimento igual a 1,0% e Cr-FAq, que obteve CIM elevado, entretanto, inibiu 86,7% de aderência bacteriana, na concentração de 62,5 µg/ml, sendo o rendimento desta fração 32%. As frações selecionadas foram submetidas a avaliações complementares, como: viabilidade bacteriana (time kill), inibição de formação e queda de pH em biofilme de S. mutans, utilizando discos de hidroxiapatita. Nos testes em biofilme, destacaram-se três frações: Lc-FHx, que em concentração 20xCIM, proporcionou redução na viabilidade do microrganismo e diminuição da formação do biofilme tratado diariamente por 5 dias; Lc-FCh, que em concentração equivalente a 20xCIM, reduziu a formação de biofilme e Cl-FHx, que além de reduzir a formação de biofilme na concentração de 20xCIM, interferiu na viabilidade do microrganismo, nas duas concentrações testadas (10xCIM e 20xCIM). A composição química das frações ativas em biofilme foi analisada por CG-EM. As demais frações testadas nesta etapa não diferiram do controle negativo (veículo) nos testes aplicados. Nenhuma das frações avaliadas afetou a redução de pH do meio pelo biofilme. Em conclusão, as frações com polaridades baixa ou intermediária das espécies Lantana camara e Copaifera langsdorffii mostraram ter potencial para gerar novos compostos anti-cárie de origem natural, tendo apresentado atividade antimicrobiana sobre o biofilme formado por S. mutans / Abstract: Despite the continuous development of knowledge, prevention and treatment of dental caries, the disease continues to have a high prevalence in Brazil and worldwide. For this reason, there is been a strong interest for new pharmacological agents that can assist biofilm control, acting against the main microorganism associated with the development of caries, Streptococcus mutans. Thus, the aim of this study was to evaluate the antimicrobial activity of the extract of four plants from Brazilian cerrado (and its fractions) against S. mutans UA159. Hydroalcoholic extracts of Lantana camara (Lc), Copaifera langsdorffii (Cl), Psidium guajava (Pg) and Cochlospermum regium (Cr) were evaluated by means of antimicrobial tests for the determination of minimum inhibitory (MIC) and bactericidal (MBC) concentrations, inhibition of adhesion and pH-drop of S. mutans. The crude extract of four plants showed antimicrobial potential and were fractionated by polarity gradient, and 4 fractions were obtained for each extract: hexane (FHx), chloroform (FCh), ethyl acetate (FAc) and aqueous (FAq) fractions. These fractions were subjected to previously mentioned tests to determine the active fraction(s) of each extract. For the subsequent evaluation step in biofilm, 6 active fractions were selected: Lc-FHx and Lc- FCl, both with MIC = 15.6 µg/ml, and yield of 9.5% and 17.5%, respectively; Cl-FHx, which showed MIC = 15.6 µg/ml, an inhibitory activity on the pH drop in solution and yield of 21%; Pg-FHx with MIC = 125 µg/ml, 93.4% of inhibition of adhesion in the concentration of 62.5 µg/ml and yield of 2.0%; Cr-FHx, with MIC = 125 µg/ml, an inhibitory activity against pH drop and a yield of 1.0% and Cr- Aq, which showed a high MIC value, however, it inhibited 86.7% of bacterial adhesion at a concentration of 62.5 µg/ml, and had a yield of 32%. The selected fractions were subjected to additional tests as bacterial viability (time-kill), inhibition of formation and pH drop in biofilms of S. mutans, using hydroxyapatite disks. Three active fractions stood out in tests on biofilm: Lc-FHx which decreased the viability of the microorganism and biofilm formation in the concentration of 20xMIC, Lc- FCx, which reduced biofilm formation in the 20xMIC concentration, and Cl ¿ FHx, which reduced biofilm formation in the 20xMIC concentration and interfered with the viability of the microorganism at the two tested concentrations (10xMIC and 20xMIC). The chemical composition of active fractions was analyzed by GC-MS. The other fractions tested in biofilm did not differ from the negative control (vehicle). None of the evaluated fractions affected the pH drop by biofilm. In conclusion, Lantana camara and Copaifera langsdorffii fractions with low or intermediate polarities showed potential to generate new naturally occurring anticarie compounds and presented antimicrobial activity against biofilms formed by S. mutans / Doutorado / Farmacologia, Anestesiologia e Terapeutica / Doutora em Odontologia

Species that become naturalized in a new geographical range, subsequently multiply and spread, and persist to the detriment of resident communities, are known as alien invasive species. Two aspects of species invasion – spread and ecological impact – were examined using Lantana camara L. (henceforth lantana) as the study system, specifically in the context of a seasonally dry tropical forest ecosystem of the Mudumalai Wildlife Sanctuary and National Park. Lantana is a thicket-forming woody shrub of South and central American origin, which is now widespread across the tropics. The thesis is divided broadly into two parts -the first part examines the influences of environmental factors on the distribution and spread of lantana while the second part focuses on the effects of lantana on the distribution, survival and growth of native woody species. Much of the work presented in this thesis was conducted within a 50 ha permanent plot (the Mudumalai Forest Dynamics Plot, MFDP hereon) in Mudumalai, chiefly because the history of invasion by lantana has been recorded here since 1989. The influence of changing resources on lantana invasion was explored at two scales -small spatial but fine temporal scale in the MFDP and at the level of the landscape. Available data on an 18 year chronosequence of changes in the qualitative density of lantana from the MFDP and field studies between the years 2009 and 2010 were used to determine the environmental correlates of lantana spread in time and space. It was found that biotic factors such as the presence of the shrub Helicteres isora and abiotic factors such as proximity to drainages and the combination of fire and drought promoted the intensification of lantana invasion in time while proximity to streams, higher total annual rainfall and low fire frequency contributed to lantana invasion at the landscape level. The impacts of lantana on the seedlings of native woody species were assessed in 10m x 10m plots within the MFDP. An initial enumeration of 60 such plots revealed that animaldispersed, dry forest habitat preferring species were most affected by the presence of dense lantana. A follow-up study comprising of growth and survival measurements made on 1105 seedlings over two years (2008-2010) further confirmed that dry forest preferring species were most affected by the presence of dense lantana and that this response at the community level was most likely influenced by the most abundantly sampled species in this habitat preference guild – Catunaregam spinosa. In conclusion, while the environmental correlates of lantana most likely promoted its invasion, only certain guilds of native species seemed to be negatively affected by the presence of lantana.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Invasive alien plants threaten natural and agricultural pollination systems as they integrate into and disrupt flower visitation networks. Mango (Mangifera indica) production on commercial mango farms in Hoedspruit, South Africa, is an important part of the local economy. Mangoes require pollination for fruiting success, and depend on the native insect community, facilitated by managed bee colonies (Apis mellifera), to pollinate flowers. Managed honeybees and wild insect flower visitors to mango have previously been observed visiting other flowering plants in surrounding natural vegetation, including the alien invasive plant Lantana camara. Lantana camara and mango share similar floral characteristics and co-occur in close proximity, so they may share pollinators/flower visitors. Here, I determined L. camara’s influence on mango flower visitation networks, specifically whether it facilitates visitation, through greater abundance and diversity of insect flower visitors (facilitation), or competes for flower visitors (competition), and whether it supports mango flower visitors when mango trees are not in flower. This study was conducted on the margins of three mango farms and bordering natural vegetation. Firstly, L. camara’s effect on mango flower visitation was investigated by comparing flower visitation to mango in plots with and without L. camara nearby. The presence of L. camara was associated with greater mango flower visitation, with increases in both flower visitor species abundance and richness. Secondly, the composition of flower visitor communities of mango orchard boundaries and bordering natural vegetation were evaluated. Although some flower visitors were shared between mango and naturally occurring plants, flower visitor community assemblages were significantly different between natural vegetation and mango orchard boundaries. In natural vegetation, flies, butterflies, wasps, wild bees and ants played a primary role in the visitation networks, whereas honeybees, wild bees and flies were the main visitors in mango orchards. The presence of L. camara significantly influenced community structure in both natural vegetation and orchards. Natural vegetation with L. camara had a more diverse flower visitor community than natural vegetation without L. camara. Lantana camara seems to facilitate mango flower visitation during mango flowering, attracting a larger visitor abundance and species richness where it occurs in bordering natural vegetation and nearby mango orchard boundaries. However, L. camara was seen to be visited by few species known to visit mango outside of mango flowering, suggesting that L. camara may benefit more from facilitation than mango. Given its extreme invasive nature and threat to local plants which sustain native pollinators, L. camara should be removed from mango orchards and bordering natural vegetation. Furthermore, farm managers are encouraged to plant and maintain indigenous flowering plants, especially plants with a facilitative value to mango, in land surrounding mango orchards to sustain native wild pollinators beneficial to mango pollination. / AFRIKAANSE OPSOMMING: Indringerplante bedreig natuurlike- en landboubestuiwingsisteme deur blombesoekingsnetwerke binne te dring en te ontwrig. Mango (Mangifera indica) produksie op kommersiële plase in Hoedspruit, Suid-Afrika, speel 'n belangrike rol in die plaaslike ekonomie. Suksesvolle mangovrugproduksie is afhanklik van bestuiwing deur inheemse insekte, gefasiliteer deur bestuurde heuningbykolonies (Apis mellifera). Dit is vantevore waargeneem dat hierdie heuningbye en inheemse insekblombesoekers ook ander blomme besoek in die omliggende natuurlike plantegroei, veral Lantana camara wat in hierdie areas ook voorkom. Lantana camara en mango deel soortgelyke blomeienskappe en groei baie na aan mekaar op die buitenste rande van mango boorde. In hierdie studie bepaal ek L. camara se invloed op mangoblominsekbesoekers, en kyk spesifiek of dit mangoblombesoeking fasiliteer, deur om die aantal blombesoekers en blombesoekerspesies te verhoog (fasilitering), of mee kompeteer vir blombesoekers (kompetisie), en of dit mangoblombesoekers onderhou wanneer mango bome nie blom nie. Hierdie studie is uitgevoer op die grensgebied tussen die mangoboorde en natuurlike plantegroei van drie mangoplase. Eerstens is L. camara se effek op mango ondersoek deur mangoblombesoeking te vergelyk tussen plotte met en sonder L. camara. Daar is gevind dat L. camara mangoblombesoeking fasiliteer deur om die aantal blombesoekers en besoekerspesies te verhoog. Tweedens is die gemeenskapsamestelling van blombesoekers in mangoboordrande en aangrensende plantegroei geëvalueer. Alhoewel sommige blombesoekers by mango én ander plante gevind word, is hul gemeenskapsamestelling aansienlik verskillend tussen die mangoboordrande en aangrensende plantegroei. Vlieë, skoenlappers, wespe, bye en miere speel 'n primêre rol in die blombesoekingsnetwerke van natuurlike plantegroei, waar hierdie rol in mangoboord-besoekingsnetwerke vervul word deur heuningbye, wilde bye en vlieë. Die teenwoordigheid van L. camara het die gemeenskapstruktuur in beide gebiede beduidend beïnvloed. Die aangrensende natuurlike plantegroei, waar L. camara voorkom, het ‘n meer diverse blombesoekersgemeenskap as dié sonder L. camara. Mangoboorde wat grens aan plantegroei, wat L. camara insluit, het soortgelyk 'n groter blombesoekerspesierykheid en aantal blombesoekers gehad. Dit blyk dat, waar hierdie plant voorkom, Lantana camara mangoblombesoeking fasiliteer tydens mangoblomtyd sowel as om 'n groter aantal blombesoekersinsekte met ‘n groter spesierykheid te lok in beide die mangoboorde en aangrensende natuurlike plantegroei. Daar is egter geen bewyse gevind wat voorstel dat L. camara mangoblombesoekers ondersteun buite mangoblomtyd nie, wat aandui dat L. camara voordeel trek uit die fasiliterende verband met mango. Gegewe L. camara se uiterse indringende geaardheid en bedreiging aan die plaaslike inheemse plantgemeenskap wat inheemse bestuiwers onderhou, word L. camara se verwydering vanuit die aangrensende plantegroei aanbeveel. Dit word aanbeveel om L. camara se fasiliterende rol te vervang deur inheemse blomplante in dié areas aan te plant en natuurlike blomplantegroei te bewaar en te onderhou.

Evarcha culicivora is a salticid with an unusual preferred diet (vertebrate blood obtained indirectly by preying on female mosquitoes that have themselves had recent blood meals) and an unusual affinity for particular plant species (Lantana camara and Ricinus communis). This thesis is a study of how individuals of this species interact with each other, with a general objective being to clarify the role of visual attention and crossmodality priming in the mate-choice behaviour of this species. E. culicivora’s courtship and display behaviour was shown to be especially complex and highly variable. Experiments on vision-based mate-choice showed that mutual mate-choice behaviour is pronounced in E. culicivora and that both sexes prefer large mates over small mates. Olfactometer experiments showed that E. culicivora is attracted to the odours of bloodfed female mosquitoes, Lantana camara and Ricinus communis and opposite-sex conspecifics. A prior diet of blood-fed female mosquitoes enhances attractiveness to the opposite sex. Opposite-sex conspecifics paired with the odour of blood-fed female mosquitoes are also more attractive. Cross-modality priming effects were investigated in other experiments that showed individuals of E. culicivora responded more to visual cues of opposite-sex conspecifics when in the presence of certain odours (of opposite-sex conspecifics, blood-fed female mosquitoes and L. camara).

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1966. / Bibliography: leaves 76-80. / v, 80 l mounted illus., tables

Evarcha culicivora is a salticid with an unusual preferred diet (vertebrate blood obtained indirectly by preying on female mosquitoes that have themselves had recent blood meals) and an unusual affinity for particular plant species (Lantana camara and Ricinus communis). This thesis is a study of how individuals of this species interact with each other, with a general objective being to clarify the role of visual attention and crossmodality priming in the mate-choice behaviour of this species. E. culicivora’s courtship and display behaviour was shown to be especially complex and highly variable. Experiments on vision-based mate-choice showed that mutual mate-choice behaviour is pronounced in E. culicivora and that both sexes prefer large mates over small mates. Olfactometer experiments showed that E. culicivora is attracted to the odours of bloodfed female mosquitoes, Lantana camara and Ricinus communis and opposite-sex conspecifics. A prior diet of blood-fed female mosquitoes enhances attractiveness to the opposite sex. Opposite-sex conspecifics paired with the odour of blood-fed female mosquitoes are also more attractive. Cross-modality priming effects were investigated in other experiments that showed individuals of E. culicivora responded more to visual cues of opposite-sex conspecifics when in the presence of certain odours (of opposite-sex conspecifics, blood-fed female mosquitoes and L. camara).

Thesis (M. Sc. (Zoology and Entomology))--Rhodes University, 2006.

Lantana camara (lantana), a thicket-forming shrub, a number of different varieties of which were introduced into South Africa as ornamental plants but which has become a serious invasive weed. Conventional control measures for lantana are expensive and ineffective and it has therefore been targeted for biological control since 1961. To date, eleven biological control agent species have become established on lantana in South Africa. However, most agents persist at low densities and only occasionally impact plant populations. Three species regularly cause significant damage, but only reach sufficiently high numbers by midsummer after populations crash during the winter. Overall, the impact of the biological control programme on the weed is negligible and this has been ascribed to the poor selection of agents for release, the accumulation of native parasitoids, differences in insect preference for different varieties of the weed and variable climatic conditions over the weed’s range. This study suggests that the importance of varietal preferences has been over-estimated. A predictive bioclimatic modelling technique showed that most of the agents established in South Africa have a wide climatic tolerance and that the redistribution and importation of new climatypes of these agents will not improve the level of control. Additional agents are required to improve the biocontrol in the temperate conditions, and also to increase damage in the sub-tropical areas where most of the agents are established and where the weed retains its leaves year round. New candidate agents that possess biological attributes that favour a high intrinsic rate of increase, a high impact per individual and that improve the synchrony between the weed and the agent in climatic conditions that promote the seasonal leaflessness of plants should receive prior consideration. A survey in Jamaica indicated that additional biological control agents are available in the region of origin but that care should be taken to prioritise the most effective agents. The various selection systems currently available in weed biocontrol produce contradictory results in the priority assigned to candidate agents and a new selection system is proposed. The biology and host range of two new candidate natural enemies, the leaf-galling weevil, Coelocephalapion camarae and the leaf-sucking mirid, Falconia intermedia were investigated for the biocontrol of lantana. The studies indicated that these have considerable biocontrol potential, in that the weevil has a wide climatic tolerance and has the potential to survive the host leaflessness typical of temperate conditions, while the mirid has a high intrinsic rate of increase, and the potential for several generations a year. Both agents caused a high level of damage to the leaves, with the weevil galling the vascular tissue in the leaf-petiole and the mirid causing chlorotic speckling of the leaves. During laboratory trials both agents accepted indigenous species in the genus Lippia. However, under multiple choice conditions these agents showed a significant and strong oviposition preference for lantana. A risk assessment and post release field trials indicated that F. intermedia is likely to attack some Lippia species in the presence of lantana, but the levels of damage are predicted to be relatively low. A possible low incidence of damage to indigenous species was considered a justifiable ‘trade-off’ for the potentially marked impact on L. camara. Preference and performance studies on the two candidate agents suggested that most of the South African lantana varieties are suitable host plants. The mirid preferred certain varieties in multiple choice experiments, but this is unlikely to affect its impact under field conditions. Permission for release was accordingly sought for both species. Finally, the challenges facing the biological control programme and the potential for improving the control of L. camara in South Africa are considered.