Biology, host range, and risk assessment supporting release in Africa of Falconia intermedia (Heteroptera: Miridae), a new biocontrol agent for Lantana camara

The ornamental hybrid shrub, Lantana camara L. (lantana), is a serious environmental weed and has been targeted for biological control in South Africa since 1961. The established biocontrol agents cause insufficient levels of damage and additional natural enemies are required to reduce the invasiveness of this weed. The lantana mirid, Falconia intermedia (Distant), is a promising new agent that was imported from the Caribbean for life history and host-range studies. The nymphs and adults are leaf-suckers that cause chlorotic speckling, which reduces the photosynthetic capacity of the plant. Biological studies indicate that F. intermedia has considerable biocontrol potential, in that it has a high intrinsic rate of increase, the potential for multiple generations a year, highly mobile adults, and a high level of damage per individual. Host-specificity trials indicated that the lantana mirid has a narrow host range, with L. camara being the most suitable host, but several indigenous African species in the closely related genus Lippia are suitable alternative host plants. Under multiple-choice conditions, adults showed a significant and strong oviposition preference for L. camara over the Lippia species. A risk assessment of potential nontarget effects indicated that three Lippia species could sustain damage levels in the field. The relatively low probability of damage to indigenous species was considered a justified trade-off for the potentially marked impact on L. camara. The regulatory authorities accepted the results of this study and F. intermedia was released against L. camara in South Africa in April 1999.     

Biological control of <Emphasis Type="Italic">Lantana camara</Emphasis> in South Africa: targeting a different niche with a root-feeding agent, <Emphasis Type="Italic">Longitarsus</Emphasis> sp.

The root-feeding flea beetle, Longitarsus sp. (Coleoptera: Chrysomelidae: Alticinae), was studied as a potential biological control agent for Lantana camara L. (Verbenaceae) in South Africa. Host range tests were carried out on 52 plant species in 11 families. Although 11 plant species, all in the family Verbenaceae, supported complete development of Longitarsus sp. during no-choice tests, the beetles showed very strong preferences for L. camara during paired-choice and multi-choice tests. The results confirm that the beetles have a narrow host range, and that under natural conditions they are highly unlikely to utilise plants other than L. camara. In the unlikely event that some of the Lippia spp. are attacked in the field, they are not expected to sustain populations of the flea beetle over time. Attributes that should enhance the biocontrol potential of Longitarsus sp. include: the adults are long-lived and highly mobile; and, the larvae cause extensive direct damage to the roots of L. camara, which could in turn expose the plants to soil-born pathogens. All indications are that Longitarsus sp. could make a substantial contribution to the biological control of L. camara in many countries around the world because the beetles pose no threat to non-target plant species and they damage a part of the plant (i.e. roots) not yet affected by any other agent species.     

The trimorphic flea-beetle, <Emphasis Type="Italic">Alagoasa extrema</Emphasis>, not suitable for biocontrol of <Emphasis Type="Italic">Lantana camara</Emphasis> in Africa

The biology and host range of the flea-beetle, Alagoasa extrema (Harold) (Coleoptera: Chrysomelidae: Galerucinae: Alticini), was studied under quarantine laboratory conditions to evaluate the insect’s suitability for release as a biological control agent for the noxious weed, Lantana camara L. (Verbenaceae), in South Africa. Identification of this species proved noteworthy. The adults of A. extrema display three freely interbreeding and very distinct colour morphs, which can be confused with no less than 11 species of Alagoasa found in Mexico and the southwestern U.S. Initially, specimens were identified as two species of the genus Alagoasa Bechyné, i.e. A. quadrilineata (Harold) and A. extrema. Thirteen additional Alagoasa species and Kushelina petaurista (F). that can be confused with A. extremabased on external morphology of adults or larvae are discussed. Favourable biological characteristics included long-lived adults, several overlapping generations per year, and high adult and larval feeding rates. Observations from the insect’s native Mexican range and studies in South Africa suggest that A. extrema would probably be more suited to subtropical, rather than temperate areas in Africa. Host-specificity studies showed A. extrema to be an oligophagous species, capable of feeding and developing on several non-target species, especially two indigenous, African Lippia species (Verbenaceae). The host suitability of these indigenous species was only marginally lower than that of L. camara, and the potential risk to them was deemed to be too high to warrant release. It was therefore recommended that A. extrema be rejected as biocontrol agent for lantana in Africa.     

Biology and host range of <Emphasis Type="Italic">Aconophora compressa,</Emphasis> a candidate considered as a biocontrol agent of <Emphasis Type="Italic">Lantana camara</Emphasis> in Africa

The shrub, Lantana camara L. (Verbenaceae), of tropical American origin, is a serious weed in South Africa and is the target of a biological control programme. The stem-sucking membracid, Aconophora compressa Walker (Homoptera: Membracidae), from Mexico was reported to be very damaging and was therefore imported into South Africa for biology and host range studies. The female partially inserts the eggs into the woody portion of actively growing stems, and guards them against potential predators. Nymphs develop through five instars to the adult stage in about 45 days. The adults and nymphs feed on the sap of stems causing the leaves to wilt, the flowers to abort and the gradual dieback of stems. No-choice experiments showed that adult survival, egg production, and nymphal emergence was high on L. camara, and also on related ornamental and indigenous species. The adult reproductive performance was higher on some indigenous Lippia species than on L. camara. Furthermore, the nymphs developed faster on these indigenous species and high rates of reproductive performance on these non-target species were sustained over several generations. In multiple-choice trials, equal or larger numbers of egg batches were recorded from indigenous Lippia species and the ornamental plant, Aloysia citrodora Palau, than on L. camara. The treehopper, A. compressa, poses an unacceptable threat to indigenous Lippia species and has therefore been rejected as a biocontrol agent for L. camara in Africa.     

Unsuitability of Charidotis pygmaea for biocontrol of Lantana camara in Africa

The host range of the tortoise beetle,Charidotis pygmaea Klug (Coleoptera:Chrysomelidae), was studied under quarantinelaboratory conditions to evaluate the insect'ssuitability for release as a biological controlagent for the noxious weed, Lantanacamara L. (Verbenaceae) in South Africa.Culturing on the target plant, L. camara,proved problematic with high larvalmortalities. Host-specificity studies showedthat four species in the genus Lantana,and two species in the genus Lippiawere acceptable as host plants. Duringlarval development trials, the insect performedbetter on the indigenous Lantana rugosaThunb. (Verbenaceae) and the introduced,commercially used L. montevidensis(Spreng.) Briq. (Verbenaceae), than on any ofthe weedy South African L. camaravarieties tested. Adult multi-choice trialsindicated that the beetle preferred to ovipositon L. rugosa and L. montevidensis.It is therefore recommended that C.pygmaea not be released against L.camara in Africa.     

Geographical range and impact of five biocontrol agents established on Lantana camara in South Africa

A survey was conducted todetermine the present status of five biocontrolagents established on Lantana camara L.(Verbenaceae) in South Africa. Three ofthe five agents, Calycomyza lantanae(Frick), Ophiomyia lantanae Froggatt andTeleonemia scrupulosa Stål areestablished throughout the range of L.camara. The two hispine beetles, Octotomascabripennis Guérin-Ménevilleand Uroplata girardi Pic are restrictedto the warm, subtropical regions in the easternrange of the weed, and are unable to cope withthe plants becoming seasonally leafless in dryand temperate areas. The two beetles and T. scrupulosa are rated as the most damagingagents on L. camara. The impact of O. lantanae is uncertain, and due to lowpopulations, the impact of C. lantanae isnegligible. Insect populations typicallyaccumulate to maximise their impact on plantsby midsummer, giving plants the opportunity tocompensate for the cumulative agent damageaccrued at the end of the previous growingseason. A number of parasitoids were rearedfrom U. girardi, O. lantanae andC. lantanae, but only those adapted toC. lantanae are expected to significantlyreduce its field density. The agents feed anddevelop on a wide range of lantana varieties,and where two or more varieties co-exist,insects occurred in equal abundance on thedifferent varieties. The importance of varietalpreferences appears to have beenover-estimated, but needs consideration whennew candidates are evaluated. The impact ofthese biocontrol agents is insufficient toreduce L. camara to a manageablesituation, and additional candidates arenecessary to control this weed in South Africa.     

Study of pollen brush in selected species of Astragalus L. subgenus Pogonophace Bunge (Leguminosae)

Nine species of Lippia (Verbenaceae) were studied by RAPD markers in order to evaluate the degree of genetic diversity. The following species were collected at the Cadeia do Espinhaço Mountains, Southeast Brazil: L. corymbosa, L. diamantinensis, L. filifolia, L. florida, L. hermannioides, L. lupulina, L. rotundifolia, L. rosella and L. sidoides. The analysis was performed using 18 primers that generated 490 fragments and only one primer was found to be monomorphic in all individuals. The average interspecific genetic distances were similar for all species and higher than the intraspecific genetic distances. Species with narrow occurrence did not show low intraspecific diversity. The molecular data were used to generate an UPGMA dendrogram that showed two major groups with a clear distribution among the species. RAPD analysis was efficient to address the genetic diversity of Lippia species and contributed to understand the adaptation to the environment, conservation and taxonomic implications.     

Suppression of growth and reproductive capacity of the weed Lantana camara (Verbenaceae) by Ophiomyia camarae (Diptera: Agromyzidae) and Teleonemia scrupulosa (Heteroptera: Tingidae)

An 8-month study was conducted to determine the effect of herbivory by the herringbone leafminer Ophiomyia camarae Spencer (Diptera: Agromyzidae) and the lace bug Teleonemia scrupulosa Stål (Heteroptera: Tingidae) on growth and reproductive capacity of their host plant, Lantana camara L. (Verbenaceae). Ophiomyia camarae adults were released into field cages at two population densities while T. scrupulosa, a widespread and naturalised biocontrol agent in South Africa, colonised and attacked uncaged plants of similar size grown under similar field conditions. At lower initial density, O. camarae reduced stem height, stem diameter, leaf density, flower density and above-ground biomass by 5, 22, 54, 100 and 41%, respectively. At higher initial density of O. camarae, stem height, stem diameter, leaf density, flower density and above-ground biomass were substantially reduced by 19, 28, 73, 99 and 49%, respectively. Teleonemia scrupulosa also reduced stem height, stem diameter, leaf density, flower density and above-ground biomass by 37, 34, 75, 100 and 50%, respectively. The root development was less affected by both O. camarae and T. scrupulosa. Whilst higher densities of O. camarae exerted noticeable herbivore pressure, T. scrupulosa herbivory substantially hampered plant growth and reproductive capacity even at lower population levels. These findings suggest that O. camarae, released in 2001 for the control of lantana, would be effective as part of a complementary guild of biological control agents. The profound effect of herbivory by T. scrupulosa on plant growth and reproductive capacity suggests that it is making a much greater contribution to the biological control of lantana in South Africa than was previously thought.     

Biology,host range and varietal preference of the leaf-feeding geometrid, <Emphasis Type="Italic">Leptostales ignifera</Emphasis>, a potential biocontrol agent for <Emphasis Type="Italic">Lantana camara</Emphasis> in South Africa,under laboratory conditions

Lantana camara L. (Verbenaceae) is a weed of major importance in South Africa. It invades indigenous forests and veld, valuable commercial and agricultural forests, plantations and orchards, as well as river-catchment areas. Several natural enemies, including insect and pathogen species, have been released in South Africa, some of which established successfully. These do not exert sufficient control and additional natural enemies are required. Leptostales ignifera Warren (Lepidoptera: Geometridae), one of several new species being investigated as potential biocontrol agents, was collected in the subtropical parts of Florida, USA and Mexico. Host specificity trials indicated L. camara to be the preferred host plant of this quick-developing, voracious leaf-feeder, with some of the African indigenous Lippia species qualifying as very marginal hosts. The possible preference that L. ignifera might have for different South African naturalized L. camara varieties was studied during quarantine laboratory preference trials. Variety 029WP was the most suitable host for L. ignifera, although the other four tested varieties were able to support viable populations of the insect. Not taking other abiotic and biotic factors such as climate and predation into consideration, once released, L. ignifera should be able to establish on all five of the tested varieties in the field and contribute to the biological control of the complex of L. camara as a whole. Based on the above studies, permission has been granted for the release of L. ignifera in South Africa.     

Chromosome numbers in the genus Lippia (Verbenaceae)

The genus Lippia (Verbenaceae) comprises about 200 taxa mainly distributed in Brazil, Mexico, Central America, Africa, Argentina and Paraguay. Some problems involving the number and delimitation of species have been reported. In order to contribute to the solving of these problems, the chromosome numbers of 14 Lippia species are documented. The following species were collected at Espinhaço Range, Southeast Brazil: Section Zapania (L. corymbosa, L. diamantinensis, L. hermannioides, L. lacunosa, L. rotundifolia, L. rubella), section Rhodolippia (L. florida, L. lupulina, L. pseudothea, L. rosella), section Goniostlachyum (L. glandulosa, L. pohliana, L. sidoides) and section Dioicolippia (L.filifolia). Immature inflorescences were collected and the ideal size for chromosome observation was determined. The majority of species have a haploid chromosome number from 10 to 14. Few species have a higher chromosome number, which suggests the occurrence of polyploidy. The relationships between chromosome numbers and the taxonomic sections are also discussed.     

Contrasting strategies to cope with drought by invasive and endemic species of Lantana in Galapagos

This study compares how Lantana camara, an invasive species, and L. peduncularis, an autochthonous one, cope with drought in Galapagos. Soil surface temperature was the abiotic environmental parameter that best explained variations in photosynthetic stress. Higher soil surface temperatures were recorded in the lowlands and in rain-shadow areas, which were also the driest areas. L. peduncularis, with a shallow root system, behaved as a drought-tolerant species, showing lower relative growth rates, which decreased with leaf water content and higher photosynthetic stress levels in the lowlands and in a northwest rain-shadow area in comparison with higher and wetter locations. Its basal and maximal fluorescences decreased at lower altitudes, reflecting the recorded drops in chlorophyll concentration. In contrast, L. camara with a deep root system behaved as a drought-avoiding species, showing leaf and relative water contents higher than 55% and avoiding permanent damage to its photosynthetic apparatus even in the driest area where it showed very low chlorophyll content. Its relative growth rate decreased more in dry areas in comparison to wetter zones than did that of L. peduncularis, even though it had greater water content. Furthermore, L. camara showed higher water contents, growth rate, and lower photosynthetic stress levels than L. peduncularis in the arid lowlands. Thus, L. peduncularis maintained lower maximum quantum efficiency of photosystem II photochemistry (F _v/F _m) than L. camara even at sunrise, due to higher basal fluorescence values with similar maximal fluorescence, which indicated permanent damage to PSII reaction centres. Our results help to explain the success and limitations of L. camara in the invasion of arid and sub-arid environments.     

South African Lippia herbal infusions: Total phenolic content,antioxidant and antibacterial activities

Lippia javanica and Lippia scaberrima are used as herbal remedies and are commercially traded as health teas in southern Africa under the brands “Mosukujane” and “Musukudu”, respectively. This study evaluates the relationship between the presence of phenolic compounds and the antioxidant activities of infusions prepared from four Lippia species (L. javanica, L. scaberrima, L. rehmannii and L. wilmsii) indigenous to South Africa. The antioxidant activities of the infusions, determined by the 2,2-diphenylpycrylhydrazyl (DPPH) method, were also compared to those of popular black, green and herbal tea brands. Of the four indigenous species, infusions of L. javanica and L. wilmsii exhibited the highest antioxidant activities (EC₅₀: 358 and 525 µg/ml, respectively) and contained the most phenolic compounds (14.8 and 14.5 mg/ml of dry weight gallic acid equivalent, respectively). Antibacterial activities of methanolic extracts of the four Lippia species were determined against four human pathogens (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa). The extract of L. javanica was the most active against all the pathogens tested. Those Lippia species (L. javanica and L. wilmsii) previously reported to produce higher levels of the pharmacologically active phenylethanoid glycosides verbascoside and isoverbascoside, portrayed stronger antioxidant and antibacterial activities. This study gives credence to the use of infusions of these Lippia species for their general health benefits.     

The suitability of non-target native mangroves for the survival and development of the lantana bug <Emphasis Type="Italic">Aconophora compressa</Emphasis>, an introduced weed biological control agent

Aconophora compressa (Hemiptera: Membracidae), a biological control agent introduced against the weed Lantana camara (Verbenaceae) in Australia, has since been observed on several non-target plant species, including native mangrove Avicennia marina (Acanthaceae). In this study we evaluated the suitability of two native mangroves, A. marina and Aegiceras corniculatum (Myrsinaceae), for the survival and development of A. compressa through no-choice field cage studies. The longevity of females was significantly higher on L. camara (57.7 ± 3.8 days) than on A. marina (43.3 ± 3.3 days) and A. corniculatum (45.7 ± 3.8 days). The proportion of females laying eggs was highest on L. camara (72%) followed by A. marina (36%) and A. corniculatum (17%). More egg batches per female were laid on L. camara than on A. marina and A. corniculatum. Though more nymphs per shoot emerged on L. camara (29.9 ± 2.8) than on A. marina (13 ± 4.8) and A. corniculatum (10 ± 5.3), the number of nymphs that developed through to adults was not significantly different. The duration of nymphal development was longer on A. marina (67 ± 5.8 days) than on L. camara (48 ± 4 days) and A. corniculatum (43 ± 4.6 days). The results, which are in contrast to those from previous glasshouse and quarantine trials, provide evidence that A. compressa adults can survive, lay eggs and complete nymphal development on the two non-target native mangroves in the field under no-choice condition.     

Introduction, Rearing, and Host Range of Aerenicopsis championi Bates (Coleoptera: Cerambycidae) for the Biological Control of Lantana camara L. in Australia

The biology and host range of the cerambycid beetle Aerenicopsis championi Bates, a potential biological control agent for the weed Lantana camara L., were studied. A. championi is a univoltine species associated with L. camara, L. urticifolia, and L. hirsuta in Mexico and Central America. In Mexico, adult emergence occurred in May and June at the start of the rainy season. Larvae fed within the stems over a 9- to 12-month period and caused damage to the plant. The insect was imported into Australia, where a procedure for rearing it in the laboratory was developed. Host-range tests indicated that adults oviposited and larvae commenced development in L. camara and L. montevidensis but not in any of 57 other species tested. A CLIMEX model indicated that most areas infested with lantana in Australia would have a favorable climate for A. championi. Permission to release this insect in Australia was obtained and three small releases were made in southern Queensland in February 1995.     

入侵植物马缨丹研究进展

马缨丹原产于热带美洲,现已扩散至世界热带和亚热带地区,并严重威胁入侵地本地植物的生长。马缨丹因具有观赏价值而被我国大量引进,但由于疏于管理,发展成为入侵杂草,对我国农业、畜牧业及生态环境造成严重危害。目前对马缨丹的入侵机制还没有全面系统的认识。本文从马缨丹的生物学特性、入侵机制、生态学效应、防治与应用等方面进行综述,总结其研究进展,以期为马缨丹的防治工作提供依据。研究结果显示:马缨丹成功入侵的关键因素源于其独特的生物学性征;对农林业造成的危害的原因主要为它的化感作用;马缨丹的防治方法主要包括物理、化学和生物防治;马缨丹在防虫除虫、污染修复、药用价值等方面有所应用。此外,分析当前研究中的不足后发现,今后应加强马缨丹在自然环境中的适应机制、应用潜力、防治方法等的研究。     

Phenylethanoid glycosides from Lippia javanica

Lippia javanica (N.L.Burm.) Spreng. is an aromatic, multipurpose medicinal plant from which a number of volatile compounds have been identified, together with toxic triterpenoids and iridoid glycosides. Two additional phenylethanoid glycosides, verbascoside and isoverbascoside, were isolated from L. javanica and characterized. High performance liquid chromatography analyses of polar extracts of three other Lippia species (L. scaberrima, L. rehmannii and L. wilmsii), indigenous to South Africa, revealed the presence of both isomers. When compared to the other indigenous Lippia species, the leaves of L. javanica were found to contain the highest concentrations of both isomers. In addition, the intraspecies variation of the verbascoside/isoverbascoside content of L. javanica, harvested from the same and different localities, was investigated. The concentrations of the two phenylethanoids remained fairly consistent within and between different populations, even when geographically separated. While these compounds are produced by many genera, they may now be added to the list of iridoid glucosides employed as chemotaxonomic markers for Lippia species.     

Cytogenetic characterization of <Emphasis Type="Italic">Lippia alba</Emphasis> and <Emphasis Type="Italic">Lantana camara</Emphasis> (Verbenaceae) from Brazil

The aim of this work was to determine the cytogenetic characteristics of Brazilian Lippia alba (Mill) N. E. Brown and Lantana camara Plum. that could be useful for future characterization of these genera. Our analyses revealed that Li. alba has 2n=30 chromosomes consisting of ten metacentric and five submetacentric pairs, while La. camara has 44 metacentric chromosomes. The large blocks of heterochromatin seen in both species suggest an apomorphic condition. Six 45S rDNA sites were detected in both species by fluorescence in situ hybridization (FISH). Two and four 5S rDNA sites were observed in Li. alba and La. camara, respectively. Meiotic analysis revealed a normal chromosomal behaviour. The number of chromosomes and the presence of 45S rDNA and 5S rDNA sites do not exclude a possible polyploid origin. The cytogenetic differences between La. camara and Li. alba may be useful markers for differentiating these species.     

Distribution and abundance of the herringbone leaf-miner,Ophiomyia camarae (Diptera: Agromyzidae) on Lantana camara (Verbenaceae) in selected areas of Swaziland

The distribution and abundance of Ophiomyia camarae was determined in three ecological regions, i.e., highveld, middleveld, and lowveld of Swaziland. Within each region, sites were selected based on Lantana camara L. density, with 10 plants randomly chosen per sampling site. Ten leaves from each shrub were collected and assessed for any damage caused by the herringbone leaf-miner. Relative abundance, based on the number of shrubs damaged by the herringbone leaf-miner, was scored per site. Three lantana varieties were observed during the sampling period. There were significant differences in mean leaf damage due to leaf-miner activity between varieties (P=0.0162), with 46±4.89% leaves of the pale pink variety damaged compared to 23±5.56 and 21±3.53% leaves of the orange and pink varieties, respectively. While there were no restrictions in terms of distribution, the highest levels of O. camarae populations were observed in the middleveld (P=0.0012), suggesting that this region had the most suitable environmental conditions for this natural enemy. Overall, the abundance was significantly different between regions (P=0.006) and months (P=0.000), with April scoring the highest population levels. Based on our observations, the variation in environmental conditions has an influence on the activity of O. camarae, with the middleveld having the most suitable conditions     

Phylogenetic relationships and taxonomy of subfamily Zygophylloideae (Zygophyllaceae) based on molecular and morphological data

Phylogenetic analysis of noncoding trnL plastid DNA sequences and morphological data for 43 species of Zygophylloideae, representing most of the morphological and geographical variation in the subfamily, indicates that the currently recognised genera Augea (monotypic, southern Africa), Tetraena (monotypic, China), and Fagonia (c. 30 species, widespread), are embedded in Zygophyllum (c. 150 species, widespread). A generic classification based on six monophyletic and morphologically distinctive entities is proposed: Roepera with c. 60 species in Australia and southern Africa, Zygophyllum with c. 50 species in Asia, Tetraena with c. 40 species in Africa and Asia, Augea with a single species in southern Africa, Melocarpum with two species in the Horn of Africa region, and Fagonia with c. 30 species in both the Old and the New World. Scanning electron microscopy studies of testa structure provided important characters for the delimitation of some genera. New combinations (61) are made in Roepera, a resurrected genus originally described from Australia, one new name is proposed in Zygophyllum, 35 new combinations are made in Tetraena, and two new combinations are made in Melocarpum (previously Zygophyllum sect. Melocarpum).     

Contributions of numerical taxonomy toOrnithogalum subg.Beryllis (Hyacinthaceae) in Morocco

In North Africa,Ornithogalum L. subg.Beryllis Baker is represented by three taxa (O. narbonense L.,O. pyrenaicum L., andO. sessiliflorum Desf.), often difficult to identify. 90 individuals from 4 localities were subjected to a biometric study based on 19 morphological characteristics. Several types of multivariate analyses allow a perfect identification of the three species. Studies on the reproductive biology, cytotaxonomy, and ecology supplement these data.