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     

Arid-adapted Mexican leafhopper, Barela parvisaccata (Hemiptera: Cicadellidae), unsuitable for biocontrol of Lantana camara (Verbenaceae) in South Africa

A host specificity study conducted in South Africa between 2000 and 2004 showed that the leafhopper, Barela parvisaccata Young, performed as well on some of the indigenous Lippia spp. as on the target weed Lantana camara L. During adult no-choice tests, B. parvisaccata reproduced on eight species of the two closely related genera, Lantana and Lippia. Although B. parvisaccata has a restricted host range, its reproductive performance on the indigenous Lippia scaberrima Sond. during the adult multiple-choice tests was unacceptably high. It was therefore concluded that B. parvisaccata was not sufficiently host-specific to be released against L. camarara in Africa.     

Host Specificity of the Argentine Root-Boring Weevil, Heilipodus ventralis (Coleoptera: Curculionidae), a Potential Biocontrol Agent for Snakeweeds (Gutierrezia: Asteraceae) in Western North American Rangelands—U.S. Quarantine Tests

Native snakeweeds, especially Gutierrezia sarothrae (Pursh) Britton and Rusby and Gutierrezia microcephala (DC.) A. Gray, are among the most widespread and damaging weeds of rangelands in the western United States and northern Mexico. The genus long ago spread to southern South America, where further speciation occurred. We have found several species of insects in Argentina that damage other species of snakeweeds there and are possible candidates for biological control in North America. The first of these, the root-boring weevil, Heilipodus ventralis (Hustache), was tested in Argentina and then sent to the USDA-ARS Insect Quarantine Facility at Temple, Texas, for host specificity testing on North American plants. We tested H. ventralis on 40 species of the family Asteraceae, in 19 tests of five types, using 686 adults and 365 larvae. Host specificity increased from adult feeding, to ovipositional selection, to larval development. At Temple, adults fed mostly on 6 species of the closely related genera Grindelia, Gutierrezia, and Gymnosperma, but with substantial feeding on four other genera of the two preferred subtribes Solidagininae and Machaerantherinae and on Baccharis in the tribe Baccharidinae, with lesser feeding on the subtribe Asterinae, all in the tribe Astereae, and on 1 species in the tribe Anthemideae. Females oviposited primarily on the same 6 species but very little on plants outside the 2 preferred subtribes. Larvae developed only on 9 of the 29 U.S. plant species tested, 6 within the two preferred subtribes and on Brickellia and Aster in other tribes. Only 5 species of three genera appear to be potential true hosts of H. ventralis in North America, on which all stages of the life cycle, adult feeding, oviposition, and larval development, can take place; these are Gymnosperma glutinosum (Spreng.) Less., Gutierrezia grandis Blake, Gut. microcephala, Gut. sarothrae, and Grindelia lanceolata Nutt. None of these genera contain species of economic or notable ecological value; the few rare species appear to be protected by habitat isolation from attack by H. ventralis. H. ventralis, therefore, appears sufficiently host specific for field release in North America. This is the first introduced biocontrol agent to be approved for release in a continental area to control a native weed.     

Effect of temperature on the survival of Aconophora compressa Walker (Hemiptera: Membracidae): implications for weed biocontrol

Abstract  In weed biocontrol, similarity of abiotic factors between the native and introduced range of a biocontrol agent is critical to its establishment and effectiveness. This is particularly the case for weeds that have a wide geographical distribution in the native range. For such weeds, the choice of a specialist insect that has narrow tolerance limits to important abiotic factors can diminish its ability to be an effective biocontrol agent. The membracid Aconophora compressa was introduced in Australia from Mexico for biocontrol of Lantana camara , a plant with a wide climatic tolerance. In this study we investigated the effect of constant and alternating temperatures on A. compressa survival. Longevity of adults and nymphs declined with increasing temperatures, and at 39°C individuals survived for less than a day. At lower temperatures, nymphs survived longer than adults. Survival at alternating temperatures was longer than at constant temperatures, but the general trend of lower survival at higher temperatures remained. Spatially and temporally, the climatic tolerance of A. compressa appears to be a subset of that of lantana, thereby limiting its potential impact.     

Effect of herbivory by Teleonemia scrupulosa on the performance of Longitarsus bethae on their shared host, Lantana camara

Herbivory by insects may change the characteristics of nutrients and secondary plant chemicals of the foliage, thereby altering the acceptability and suitability of the plant for oviposition, feeding and development for subsequent herbivores. In the current study, the effect of herbivory by the sap-sucking lace bug, Teleonemia scrupulosa Stäl (Heteroptera: Tingidae), on the suitability of Lantana camara L. (Verbenaceae) for the root-feeding flea beetle, Longitarsus bethae Savini & Escalona (Chrysomelidae: Alticinae), was investigated under laboratory conditions. Preference of adult L. bethae was not influenced by the intensity of feeding damage caused by T. scrupulosa adults. However, high densities of T. scrupulosa nymphs and their feeding damage caused L. bethae adults to emigrate and colonize less infested or uninfested plants. Oviposition by L. bethae was significantly reduced at high densities of T. scrupulosa nymphs. While low infestation of T. scrupulosa had no effect the survival of L. bethae, moderate and high infestations caused significant reduction in percentage survival of L. bethae. The number of T. scrupulosa nymphs was negatively correlated with the percentage survival of L. bethae. Neither the duration of development nor the body size of L. bethae was influenced by the intensity of T. scrupulosa infestation. Overall, undamaged or slightly damaged plants that allowed better survival of L. bethae were often chosen as oviposition sites in preference to those that were highly infested, and on which survival was poor. Although the present study indicates the likelihood of inter-specific competition between L. bethae larvae and T. scrupulosa, this is likely to be mitigated by female flea beetles choosing to oviposit on less infested or uninfested plants in the field.     

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.     

Suitability of some Lantana camara varieties as host plants for the root-feeding flea beetle, Longitarsus bethae

Compatibility between the root-feeding agent Longitarsus bethae Savini & Escalona and the varieties of the target weed Lantana camara L. could influence the chances of successful establishment and effectiveness of this agent as a biocontrol agent of lantana in South Africa. Laboratory experiments were conducted to determine the influence of major South African lantana varieties on feeding, colonization, oviposition preference and larval survival of L. bethae. Feeding preference and the number of adults per plant varied among the varieties. The most damaged and colonized varieties were 150 Orange, 009 Light Pink and 113 Dark Pink. Variety 018 Dark Pink was the least damaged, while 021 Total Pink and 029 White Pink were the least colonized. Females laid the highest number of eggs on variety 150 Orange. The lowest number of eggs was recorded on Australian Richmond Pink and the closely related species Lippia wilmsii. Larval survival differed significantly among the varieties. The highest survival was recorded on 150 Orange. Duration of development also varied significantly among the varieties, with the slowest rate of development recorded on variety 029 Light Pink and the quickest on variety 015 White Yellow. Although variations in female body size were less significant among varieties, males emerging from variety 150 Orange were slightly smaller than those emerged from other varieties. There was a significant tendency for females to select varieties that enhanced the survival of their offspring, which met the predictions of the preference-performance hypothesis. The data suggest that the chances of establishment and successful control of the weed are expected to be much greater on those varieties that were preferred for oviposition and provided better larval performance.     

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.     

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.     

Additions to the mycobiota of the weed Lantana camara (Verbenaceae) in southeastern Brazil

A sequel to the work of systematic surveying the mycobiota of Lantana camara aimed at finding potential biocontrol agents, was carried out during 1995–1996 covering part of its centre of origin in Brazil (state of Minas Gerais). Fifty-eight sampling sites, representing the four main climatic types in the state of Minas Gerais, were surveyed. Additional ad hoc collections were made in the states of Bahia, Espírito Santo, Paraná Rio de Janeiro and São Paulo. Fifteen fungal species were recorded in association with L. camara including the previously undescribed species Phomopsis lantanae-glutinosae sp. nov. Five fungi are also newly recorded on this host in Brazil: Cercospora lantanicola Corynespora cassiicola Meliola ambigua Mycovellosiella lantaniphila and Phomopsis lantanae. The following fungi, previously recorded on L. camara in Brazil, are recorded here for the first time in Minas Gerais: Dendryphielia aspera Micropustulomyces mucilaginosus Mycovellosiella lantanae Pseudocercospora guianensis and Puccinia lantanae.     

Impact of Crown Rust (Puccinia coronata f. sp. avenae) on Competitive Interactions between Wild Oats (Avena fatua) and Stipa (Nassella pulchra)

Crown rust of oats (Puccinia coronata f. sp. avenae) was investigated as a biocontrol agent for wild oats (Avena fatua) on San Clemente Island, California. Successful restoration of the native habitats of this island will involve the reduction of wild oats and revegetation with native grasses such as stipa (Nassella pulchra). Determination of the outcome of interference between wild oats and stipa is important in the prediction of the success of the biocontrol agent. An addition series design was used to investigate these interactions, with densities of each species ranging from 0 to 2000 seeds per m². Eight replicates were established, four of which were randomly chosen and infected with the pathogen. After 75 days, plant height, dry weight, and seed production were measured. The data were fit to a hyperbola surface model by use of a nonlinear regression procedure. Results indicate that wild oat is the superior competitor at the seedling stage; however, early rust infection greatly reduces fitness of wild oats, causing an increased fitness for stipa. Simulations with a plant community model constructed from the results of the greenhouse experiment and information in the literature indicated that an equilibrium may be established between wild oat and stipa if high initial seeding rates of stipa are used in revegetation.     

增温对入侵植物马缨丹生物量分配和异速生长的影响

气候变暖已是不争的事实。外来入侵植物随着温度升高有可能作出积极的响应,采取有效策略来扩大入侵范围,造成更大的危害。以世界性杂草马缨丹(Lantana camara)为研究对象,对不同温度处理下(22、26℃和30℃)的生长和分配特征及构型效应进行对比研究,并借助异速生长分析方法,对不同温度下马缨丹幼株各构件生长关系进行分析。结果表明:随着温度升高,马缨丹幼株减少了对地下生物量的分配,地上部分生物量投资的增加主要表现在对茎的投资上,并利用有限的叶生物量投资扩大叶面积,即在高度和广度两方面都增加了对光能的获取。这些响应有利于其同化作用的增强从而提高竞争力,表明温度增加会增强马缨丹的入侵力,这也是马缨丹在全球气候变暖背景下扩大其分布范围的有效策略。     

Biology and host range of Ophiomyia camarae, a biological control agent for Lantana camara in South Africa

The herringbone leaf-mining fly, Ophiomyiacamarae Spencer, is a promising candidateagent for the biological control of the alieninvasive weed Lantana camara L. in SouthAfrica. During extensive host-specificity testsinvolving 39 test plant species from 12families, survival to adulthood was restrictedto L. camara, L. trifolia, and fourspecies of the closely-related genus Lippia (Verbenaceae) in no-choice tests. However, survival of the immature stages wassignificantly lower on L. trifolia andthe four Lippia species than on L.camara. In addition, O. camaraedisplayed very strong oviposition preferencefor L. camara during paired-choice tests.This narrow laboratory host range suggests thatO. camarae will not pose any risks tonon-target verbenaceous plants if released inSouth Africa. Permission to release O. camaraeinto South Africa was approved by the regulatoryauthorities in 2001.     

Status, invasiveness and environmental threats of three tropical American invasive weeds (Parthenium hysterophorus L., Ageratum conyzoides L., Lantana camara L.) in India

Invasive weeds have threatened the integrity of ecosystems throughout the world. They affect not only the species diversity of native areas but also their biological integrity. In India, a number of invasive exotic weeds have been reported but some viz. Parthenium hysterophorus, Lantana camara and Ageratum conyzoides, especially those from tropical America are troublesome and have caused adverse ecological, economic and social impact. These weeds can be seen growing in different landscapes but are luxuriantly localized in unattended forests and cultivated areas. Parthenium hysterophorus (Asteraceae, commonly known as congress grass) is perhaps the most troublesome and noxious weed of urban and rural India. Besides rapidly colonizing areas replacing the native vegetation, it is also known to cause a number of human health problems such as skin allergy, rhinitis and irritation to eyes of the residents in the vicinity. Likewise, it causes fodder scarcity in addition to being unpalatable and toxic to livestock. Lantana camara (Verbenaceae), another serious tropical American pest, has encroached upon large areas of land, especially the forests where it has virtually replaced the forest floor vegetation and reduced tree growth. Also because of its bushy and spreading type of growth it obstructs forest operations. The third weed, Ageratum conyzoides (Asteraceae, Billy goat weed) has invaded agricultural fields. It interferes with crops and causes yield reductions of major staple crops of India. When it invades rangeland areas, it out competes native grasses causing scarcity of fodder. These weeds have similar growth strategies such as fast growth rates, short life-cycles, greater reproductive potential, high competitive abilities and allelopathy that make them successful invaders of native habitats. Mechanical, chemical, biological and cultural control tactics have failed individually, though integrated approaches combining all these approaches along with community participation and proper land management have been relatively successful. This paper presents various aspects of biology, ecology, hazards and control measures of these weeds.     

Biology, distribution and host-range of the sawfly,Lophyrotoma zonalis (Hym. pergidae), a potential biological control agent for the paperbark tree,Melaleuca quinquenervia

Since its introduction into southern Florida at the beginning of this century, the Australian paperbark tree,Melaleuca quinquenervia (Cav.) S. T. Blake, has become a major economic and environmental pest. A project to develop biological control agents for this tree in Australia began in 1986. Among a number of potential agents, a defoliating sawfly,Lophyrotoma zonalis (Rohwer) (Hymenoptera: Pergidae), was selected for further study. The larvae of this sawfly are conspicuous defoliators ofMelaleuca trees in northern Queensland. We collected these sawflies from Cairns to Mackay in northern Queensland, and they are also known from the Northern Territory and New Guinea. The life-cycle from egg to adult takes about 12 weeks. The egg, larval and pupal stages are parasitized by dipteran and hymenopteran parasites. We conducted 2234 larval no-choice feeding tests on 46 plant species from 20 families. Although feeding occurred on 35 of these plant species,M. quinquenervia and its close relative,M. leucadendra (L.) L., were preferred. In oviposition tests, larvae only emerged from egg cases laid onM. quinquenervia andM. leucadendra. Our extensive field surveys of nearly 70 tree species foundL. zonalis eggs and larvae only on several closely relatedMelaleuca species. The potential effectiveness of this sawfly as a biocontrol agent is discussed and estimated using the Goeden-Harris scoring system. Quarantine studies of this insect began in Florida in early 1994.