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.     

Fungal degradation of lantadene A, the pentacyclic triterpenoid hepatotoxin of lantana plant

Seven white-rot fungi, known to degrade complex biomolecules and xenobiotics were used for investigation on biodegradation of lantadene A (LA), the bioactive pentacyclic triterpenoid of Lantana camara. Pleurotus sajor-caju and Merulius tremellosus PRL-2845 did not degrade LA. Trametes versicolor MTCC-138, Heterobasidion annosum MTCC-146, Phellinus pini RAB-83-19, Pleurotus ostreatus MTCC-142 and Phlebia radiata 2 utilized LA to the extent of 11–15.7%. This is the first report on the fungal degradation of a pentacyclic triterpenoid.     

马缨丹总岩茨烯对小菜蛾和斜纹夜蛾幼虫的拒食作用

从马缨丹叶片中提取总岩茨烯,测定总岩茨烯对小菜蛾2龄幼虫和斜纹夜蛾1、2龄幼虫的拒食作用.结果表明,在非选择性试验中,1.6 mg·ml^-1的总岩茨烯对小菜蛾2龄幼虫和斜纹夜蛾1龄幼虫有拒食作用,8 h的拒食率分别为62.%和31.1%;在选择性试验中,0.4 mg·ml^-1的总岩茨烯即对小菜蛾2龄幼虫有拒食作用,0.4、0.8和1.6 mg·ml^-1浓度处理下的拒食率分别为52.7%、55.5%和78.9%;总岩茨烯只有在高浓度(1.6 mg·ml^-1)时,才对斜纹夜蛾1龄幼虫有拒食作用,拒食率仅为33.0%.在选择性和非选择性试验中,总岩茨烯对斜纹夜蛾2龄幼虫均无拒食作用.     

马缨丹及其酚类化合物对水葫芦生长的抑制作用

研究了马缨丹(Lantana camara)叶提取物及其酚类化合物对水葫芦（Eichhornia crassipes）生长及其生理生化指标的影响.结果表明, 马缨丹鲜叶水提物对水葫芦生长有明显的抑制作用.在较高浓度(＞30g FW·L^-1)下6 d可使水葫芦整株干枯死亡.经过高效液相色谱分离确定马缨丹水提物含有7种酚类化合物,分别为水杨酸、龙胆酸、雷琐酸、香豆素、阿魏酸、对羟基苯甲酸和6-甲基香豆素,在马缨丹鲜叶水提液中的浓度分别为50.95、13.46、5.28、3.36、2.92、2.19 和0.34 mg·L^-1.7种化合物的混合物对水葫芦抑制程度最大,其次为水杨酸,再次为6-甲基香豆素、香豆素,对羟基苯甲酸对水葫芦也有明显的抑制作用,而龙胆酸、雷琐酸、阿魏酸对水葫芦的抑制作用较小.     

Tsetse flies are attracted to the invasive plant Lantana camara

In tsetse both sexes feed exclusively on the blood of vertebrates for a few minutes every 2-3 days. Tsetse flies seek cover from high temperatures to conserve energy and plants provide shelter for tsetse in all the biotopes they occupy. Recently, tsetse have taken cover in plantations and under the invasive bush Lantana camara that has invaded large areas of the tsetse fly belt of Africa. Flies from such refugia are implicated in sleeping sickness epidemics. In a wind tunnel we show that both foliage and an extract of volatiles from foliage of L. camara attract three tsetse spp. from different habitats: Glossina fuscipes fuscipes (riverine), G. brevipalpis (sylvatic) and G. pallidipes (savannah). Gas chromatography analysis of volatiles extracted from leaves and flowers of L. camara coupled to electroantennograme recordings show that 1-octen-3-ol and beta-caryophyllene are the major chemostimuli for the antennal receptor cells of the three tsetse spp. studied. A binary mixture of these products attracted these flies in the wind tunnel. The gas chromatography linked electroantennograme analysis of the L. camara extracts also show that the antennal receptor cells of the three tsetse spp. respond similarly to groups of volatiles derived from the major biosynthetic and catabolic pathways of plants, i.e. to mono- and sesquiterpenes, to lipoxidation products and to aromatics. Mixtures of these plant volatiles also attracted tsetse in the wind tunnel. These findings show that tsetse flies have conserved a strong sensitivity to volatile secondary products of plants, underlining the fundamental role of vegetation in tsetse survival.     

Feeding and survival of the malaria vector Anopheles gambiae on plants growing in Kenya

The propensity of the malaria vector mosquito Anopheles gambiae Giles (Diptera: Culicidae) to ingest sugars from various plants, and subsequent survival rates, were assessed with laboratory-reared males and females offered eight species of plants commonly cultivated and/or growing wild in western Kenya. In cages (no-choice bioassay), mosquitoes given the opportunity to feed on castorbean (Ricinus communis L.) had the longest survival times (mean and median survival time of 6.99 +/- 0.23 and 5.67 +/- 0.17 days, respectively), comparable to mosquitoes given 6% glucose (mean and median survival time of 8.70 +/- 0.23 and 6.67 +/- 0.33 days, respectively). Survival rates of An. gambiae were low on the other plants, comparable to mosquitoes given only water. Three plants: sweet potato (Ipomoea batatas L.), wild sage (Lantana camara L.) and castorbean provided levels of sugar ingestion by both sexes of An. gambiae detectable using the cold anthrone method, showing a positive correlation between median survival and sugar consumption (Spearman rank correlation coefficient = 0.905, P < 0.0001). Equal numbers of males and females were released in an enclosed semi-field screenhouse system containing a range of local plants, but no host for blood, and allowed to feed ad libitum: 6.7 +/- 0.5% (11/64) of those recaptured were found to contain detectable fructose (all females). Common plants are clearly a viable source of nutrition for adult female An. gambiae, as well as males, and may constitute and important resource for this important malaria vector.     

生长调节剂对马蹄金外植体离体培养的影响

以草坪地被植物马蹄金的无菌苗子叶、叶片和下胚轴作为外植体进行离体培养,探讨了不同植物生长调节剂对其愈伤组织诱导及分化的影响.结果表明,从不同外植体在含有不同生长调节剂的诱导培养基中进行离体培养时,都可诱导出愈伤且出愈率为43.3%～100%,其中诱导培养基(MS 100 mg/L水解酪蛋白 0.5 mg/Lα-NAA 0.2 mg/L ZT)适合于三种外植体的愈伤诱导,出愈率为100%,愈伤生长旺盛.在所有愈伤分化试验中均形成了绿色芽点,其频率为25.0%～95.0%,仅从下胚轴诱导的愈伤分化获得了再生植株,且在分化培养基(MS 100mg/L水解酪蛋白 0.1 mg/Lα-NAA 3.0 mg/L 6-BA)上的最高愈伤分化频率为20.0%.     

马缨丹叶片水提物与挥发油的生物活性及化学成分研究

研究了马缨丹 ( Lantana camara L.)叶片水提物和挥发油水溶液的化感作用。结果表明 ,马缨丹叶片水溶物浓度在 0 .2 5 g FW m L- 1时 ,对所有受试植物的幼苗生长均有一定的抑制作用 ,浓度降至 0 .1 0 g FWm L- 1时 ,其抑制作用显著降低 ;马缨丹叶片挥发油水溶液在浓度为 1 0 0、2 0 0、30 0 μg m L- 1时 ,对受试植物均有很强的抑制作用 ,且具有明显的浓度效应。采用 GC/MS分析了马缨丹叶片挥发油的化学成分 ,鉴定了 1 9种化感物质 ,其中α-子丁香烯和β-子丁香烯为主要物质 ,分别占挥发油含量的 1 6 .2 9%、2 2 .2 9%。     

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.     

Lantana camara for fuel ethanol production using thermotolerant yeast

AIM: Evaluation of Lantana camara's use as feedstock for fuel ethanol production. METHODS AND RESULTS: Lantana camara plant material was hydrolysed with 1% sulfuric acid for 18 h at room temperature, followed by heat treatment of 121 degrees C for 20 min. Hemicellulosic hydrolyzate was separated and used for detoxification by ethyl acetate and overliming. Cellulosic fraction was hydrolysed with Aspergillus niger crude cellulase enzyme for 18 h at 55 degrees C. Using 15% (dw/v) substrate 73 g l(-1) total reducing sugars were obtained to give 78.7% hydrolysis of carbohydrate content. Acid and enzyme hydrolyzates were mixed equally and used for fermentation with thermotolerant Saccharomyces cerevisiae (VS(3)). Yeast fermented L. camara hydrolyzate well with a fermentation efficiency of 83.7% to give an ethanol yield of 0.431 +/- 0.018 g ethanol pre g sugar and productivity of 0.5 +/- 0.021 g l(-1) h(-1). CONCLUSIONS: Even though inhibitors were present in L. camara hydrolyzate, maximum sugars were utilized by thermotolerant yeast. SIGNIFICANCE AND IMPACT OF THE STUDY: Use of L. camara for fuel ethanol production with improved strains and detoxification can be recommended.