NEWSLETTER No. 17 December, 2008

Chromolaena odorata : the benevolent dictator?

Lindsey Norgrove 1,* , Roberto Tueche 1, Julia Dux 1,2 and Prosper Yonghachea 1,3

1 University of Hohenheim Project, IITA Cameroon, BP2008 Messa Yaoundé, Cameroon 2 Institut fűr Geműse und Zierpflanzenbau, 14979 Grossbeeren, Germany 3 University of Hohenheim, Institute of Biodiversity and Land Rehabilitation in the Tropics and Subtropics, 70599 Stuttgart, Germany

* Corresponding author’s current address: CABI, rue des Grillons 1, 2800 Delémont, Switzerland. [email protected]

INTRODUCTION Farmers in Côte d’Ivoire reported that C. odorata helps to prevent the establishment of I. cylindrica (de Rouw, 1991). Cameroon is located from 1° to 14°N and 8° to 16°E, To assess competition with C. odorata , we planted bordering Nigeria, Chad, Central African Republic, Congo, I. cylindrica rhizomes in pots containing soils collected from Gabon and Equatorial Guinea. In Cameroon, savannah, C. odorata- invaded savannah and forest in Central odorata (L.) King & Robinson reaches 3m height, flowering Cameroon, and measured growth of I. cylindrical rhizomes at the beginning of the dry season in December. It invades and the relations of the grass with seedbank dynamics. We forest gaps, cropped fields, cleared forest land and fallows, harvested emergent communities after six months, counting open grasslands and savannahs. Susceptible to shade, it and weighing individual . cylindrica biomass becomes less prominent and disappears as fallows age, being production per pot was significantly affected by soil origin outcompeted by understorey Marantaceae and Zingiberaceae with the lowest imperata biomass produced in the C. odorata - and pioneer tree species. However, where these species are invaded soils. When C. odorata mass was added as a absent, C. odorata may persist. covariate in this model, it was significant (P < 0.05) and was negatively correlated with the biomass of I. cylindrica, hence COMPETITION WITH MORE NOXIOUS WEEDS growth of imperata was reduced by the presence of C. odorata (Norgrove, 2007) . Imperata cylindrica L. Rauesch is a pantropical grass of the tribe Andropogoneae, subtribe Saccharine. It infests nearly EFFECTS ON COMMUNITIES 500 million acres of plantation and agricultural land world- wide. In West , it is common in the moist savannah belt In the North West province of Cameroon, we looked at the between Senegal and Cameroon. Its origin is disputed and impact of C. odorata invasion on plant community subspecies may be native to West and Central Africa or may composition in six paired invaded and non-invaded savannah originate elsewhere (den Breeyen, pers. comm.). Imperata sites. We found no effect of invasion on mean species cylindrica is difficult to manage as a fallow, dieback in the number, yet community composition was affected. There was dry season creates a fire risk, and its sucrose-rich rhizomes a loss of monocotyledonous species, including Aframomum attract rodents that eat crop seeds and destroy seedlings. In spp. and Murdannia simplex, and accompanying co-invasion western Cameroon, where some of the largest expanses of by some dicotyledonous alien weed species, notably I. cylindrica in the country are present, the local name in Oldenlandia sp., Stachytarpheta cayennensis and Ageratum Mbo-o language is ”mbuen” meaning something cruel that conyzoides . Areas invaded with C. odorata had twice the sterilises the soil. Imperata cylindrica land is avoided by plant biomass (9.44Mg ha -1) of non-invaded areas (4.52Mg farmers (Yonghachea, 2005). ha -1). Furthermore, C. odorata addition to savannah systems Chromolaena odorata Newsletter 17, December 2008 increased litter N and K inputs. C. odorata leaves contained DIFFERENT LIVELIHOODS, DIFFERENT 40mg g -1 of N and 23mg g -1 of K, compared with 6-10mg g -1 PERCEPTIONS N and 11-17mg g -1 K for grasses (Yonghachea, 2005). In North West province, the dominant Aghem people use a SOIL FERTILITY CHANGES? shifting cultivation system whereby land is cultivated for four years and then abandoned for at least five years. In the first Farmers in Cameroon have reported that they associate year of cultivation, referred to as “sùfuwo” (new farm), soil C. odorata presence with higher soil fertility (Yonghachea, mounds called “ekang” are made, filled with vegetation and 2005). Likewise, in Ghana, farmers consider both C. odorata burned. Maize ( Zea mays ), cocoyams ( Xanthosoma and earthworm casts as indicating good soils and link these sagittifolium ), sweet potatoes ( Ipomoea batatas ), cassava mechanistically by stating that C. odorata provides litter (Manihot esculenta ) and beans ( Phaseolus vulgaris) are input, shade, and a moist environment which promotes planted. In the second year called “udung”, the mounds are earthworm activity (Adjei-Nsiah et al ., 2004). In southern rearranged into ridges and maize, cocoyams and cassava are Cameroon, Norgrove and Hauser (1999) found that weed cultivated. In the third year, known as “kibvo”, only ground- biomass, dominated by C. odorata , explained 76% of nuts ( Arachis hypogeae ) and maize are planted. By the fourth variation in earthworm cast production in a cropped field. year of cultivation, “tilù”, maize and cowpeas ( Vigna Subsequently, in an adjacent site, Norgrove et al . (2003) unguiculata ) are grown and then the field is abandoned. If the found that mulching with C. odorata resulted in an increase fallow is dominated by I. cylindrica rather than C. odorata , in cast production and that these casts were richer in nitrogen the land is only cropped with Vigna subterranea (bambara and potassium than those derived from non-mulched plots, groundnut) in year 1, groundnut in year 2 and cowpea in year probably due to feeding on the N- and K-rich C. odorata 3 before fallowing. residue. To verify these observations, we measured soil biological, physical, and biochemical parameters in different The farming Aghem people consider C. odorata as the “least– land uses systems in replicated trials in central and northwest worst” option for fallows. In these fields they grow a greater Cameroon. diversity of crops (Yonghachea, 2005). The use of a biological control agent for C. odorata in this zone would Soil compaction was assessed by bulk density and a static result in greater infestation of I. cylindrica and greater weeding drudgery. However, for their pastoralist transhumant hand penetrometer. Topsoil (0-5cm) bulk density was lower neighbours, the Fulbe, relying on grazing savannah land, (p < 0.01) in C. odorata -invaded areas (0.87Mg m -3) than in C. odorata negatively affects their livelihood strategy. savannah (1.04Mg m -3). Soil resistance was lower ( P = 0.02 ) under C. odorata (1742kPa) than under savannah (3239kPa). CONCLUSIONS Morning, midday and evening topsoil temperatures were always lower ( P < 0.0001 ) under C. odorata (24.1; 25.3; In conclusion, in the context of land users in Cameroon, 26.8°C) than under savannah (27.1; 29.4; 28.5°C) (Tueche C. odorata invasion in savannahs may have had both negative and Norgrove, unpubl.). and positive effects. Chromolaena odorata -invaded areas are associated with higher topsoil N status, higher soil faunal In the same sites, we also evaluated earthworm species densities and activities. This is an association, so cause and richness (Norgrove et al ., 2008). We found that earthworm effect cannot be distinguished, yet there are plausible species richness was higher in C. odorata invaded savannah mechanistic models to offer an explanation. Chromolaena than in non-invaded savannah and there was a significant odorata maintains a canopy during the dry season so is less increase in the earthworm density. Two pantropical species, flammable (Norgrove, pers. obs) and prone to wild fires so N Dichogaster annae and Nematogenia panamaensis , were volatilisation in these areas is reduced. Therefore, N and C found exclusively in C. odorata -invaded sites (Norgrove et are retained and returned to the soil through litterfall and al ., 2008). Similarly, in land-use assessments in southern decomposition. Consequently, soils may have have higher Cameroon, these species were found only in C. odorata soil faunal and soil enzyme activity. fallow (Birang et al ., 2003). Such widespread species may be better adapted to high nutrient environments such as that In these savannahs, C. odorata does cause species shifts with under a C. odorata canopy and such conditions may also an increase in alien weeds and/or unpalatable species. Thus permit increases in the population densities of native savannahs are rendered less useful for grazing and this Eudrilidae. negatively affects pastoralists’ livelihoods. However, for farmers, a reduction in C. odorata abundance through Beta (ß)-glucosidase is the final enzyme of the cellulase biological control or other mechanisms may result in a more system which hydrolyses cellulose to glucose. Cellulose problematic weed community dominated by I. cylindrica , so comprises 40-70% of total litter mass and its decomposition management options should be considered within cultural and mineralization rates may be limiting factors within the context. soil carbon cycle. We found that ß-glucosidase activity was twice as high in C. odorata -invaded savannah than in REFERENCES uninvaded sites of similar soil chemistry (10 compared with 20ug g -1 soil h -1). Furthermore, activity could be promoted by Adjei-Nsiah S., Leeuwis C., Giller K.E., Sakyi-Dawson O., the addition of C. odorata residue whereas comparable Cobbina J., Kuyper T.W., Abekoe M. & Van Der Werf W. amounts of grass residues did not increase activity (Dux, 2004. Land tenure and differential soil fertility management 2005). practices among native and migrant farmers in Wenchi,

2 Chromolaena odorata Newsletter 17, December 2008

Ghana: implications for interdisciplinary action research. timber plantation after introducing understorey crops. Netherlands Journal of Agricultural Sciences 52: 331-348. Pedobiologia 43: 666-674.

Birang M., Hauser S., Brussaard L. & Norgrove L. 2003. Norgrove L., Nkem J.N. & Hauser S. 2003. Effects of residue Earthworm surface casting activity on slash-and-burn cropped management on earthworm cast production after land in undisturbed Chromolaena odorata and young forest Chromolaena odorata short fallow in the humid tropics. fallow in southern Cameroon. Pedobiologia 47: 811-818. Pedobiologia 47: 807-810.

Dux J. 2005. Impact of leaf residues of Imperata cylindrica , Norgrove L., Yonghachea P.F. & Csuzdi C.S. 2008. Chromolaena odorata and Phyllanthus discoideus on soil Earthworm diversity and densities in land invaded by enzyme activity, 86 pp. November 2005. Master’s thesis. Imperata cylindrica and Chromolaena odorata in the Department of Soil Science, Humboldt University, Germany, Western Cameroon Highlands. In: Pavlíček T..& Canet P. October 2005. (eds) Advances in Earthworm III, pp. 163-173. En Tipis Publishers. Nicosia, Cyprus. Norgrove L. 2007. Performance of Imperata cylindrica in relation to light availability on soils from the tropical forest- Rouw A. de 1995. The fallow period as a weedbreak in savannah boundary in central Cameroon. In: Tokarska-Guzik shifting cultivation (tropical wet forests). Agriculture, B., Brock J.H., Brundu G., Child L., Daehler C.C. & Pyšek Ecosystems and Environment 54: 31-43. P. (eds) Plant Invasions: Human Perception, Ecological Impacts and Management , pp. 277-288. Backhuys Publishers, Yonghachea P.F. 2005. Farmers’ perceptions of Imperata Leiden, The Netherlands. cylindrica and Chromolaena odorata fallows in the North West, South West and Littoral Provinces of Cameroon. Norgrove L. & Hauser S. 1999. Effects of tree density and Master’s thesis, University of Hohenheim, Germany, October crop management upon earthworm cast production in a young 2005.

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Occurrence of Aphis spiraecola on Chromolaena odorata in Nigeria: implications for pest outbreaks and the need to control the weed

Uyi Osariyekemwen Uyi 1* , Charles Izegboya Aisagbonhi 2 and Nathaniel Ikponmwosa Egbon 1

1African Regional Postgraduate Programme in Insect Science, University of Ghana, Legon, Ghana 2 Entomology Division, Nigerian Institute for Oil Palm Research, Benin City, Nigeria

*Corresponding author’s e-mail: [email protected]

INTRODUCTION MATERIALS AND METHODS

Chromolaena odorata (L.) King and Robinson was first The study was carried out at the Nigerian Institute for Oil reported in Nigeria in 1937, probably introduced through the Palm Research (NIFOR), Benin, Nigeria between August importation of contaminated Gmelina arborea Roxb. seeds to 2004 and January 2005. The study area has a bimodal rainfall Nigeria from Sri Lanka (Ivens, 1974). Chromolaena odorata pattern with annual precipitation of over 1600mm and a mean is now widespread in the southern parts of Nigeria, being annual temperature of 26.7 0C. present in more than 20 of the 36 states. The weed dominates by colonizing the forest margins, rangelands, plantations and Four 100m line transects, running in different directions and arable crop farms. haphazardly laid out in a C. odorata-infested field, were sampled weekly for the presence of A. spiraecola , using the Chromolaena odorata is known to harbour some important systematic and stratified sampling method described by pests of crops, notably (L.) Hammond (1992). Four quadrats of 1m 2 each, the positions of (Orthoptera: Pyrgomorphidae) and Aphis spiraecola (Patch) which were randomly selected along each of the 100m (Homoptera: Aphididae) (Oigiangbe et al ., 2007). A non- transects, were sampled for collection of data. Sampling was nutritional relationship between C. odorata and Z. variegatus conducted weekly between 07h00 and 10h00 from August causes increased populations and pestilence of the 2004 to January 2005. The number of C. odorata plants grasshopper in West Africa (Boppré, 1991). Aphis spiraecola within each 1m 2 quadrat was counted and each plant was is thought to be East Asian in origin but is now widely thoroughly examined for aphids. Within each quadrat, the distributed across several continents. Kranz et al . (1977) number of aphid-infested and non-infested C. odorata plants reported the aphid on over 65 plant genera, including as well as the number of aphids per plant were counted. It economically important crops like citrus, cacao, papaya, was observed that aphid-infested C. odorata developed annona and some vegetables. It is the main aphid pest of mottled leaves (abnormal leaf formation), so the number of citrus worldwide (Pfeiffer et al ., 1989). The use of C. odorata mottled C. odorata leaves per plant was also counted weekly. by A. spiraecola poses the concern of a possible pest outbreak The ant Crematogaster africana Mayr (Hymenoptera: in citrus plantations and garden eggplant farms in Nigeria. An Formicidae) was always found associated with the aphid. understanding of the relationship between C. odorata and Data were collected on mottled leaf numbers and C. africana A. spiraecola as well as the population dynamics of the aphid for three months (late October 2004 to mid-January 2005) to in C. odorata-infested areas is vital to the success of any investigate the ant-aphid relationship. A linear regression was control effort against the aphid. This paper attempts to fitted to data to determine relationships between A. spiraecola provide such information from Nigeria and we expect that population, climatic parameters, damage to the plants and ant this study will add to the existing information on the numbers. A t-test was conducted to determine levels of menacing effects of C. odorata in the tropics. significance (Genstat statistical software version 9.0).

Table 1. Mean density (± S.E.) of Chromolaena odorata plants and Aphis spiraecola along transects over a 6-month sampling period (n = 64 quadrats sampled per month). Mean monthly temperatures and RH are indicated. No. chromolaena plants No. Aphis Mean temperature Mean Relative Month m-2 spiraecola m -2 (°C) Humidity (%) August 2004 7.5 ± 0.2 445.2 ± 14.5 25.3 90 September 4.0 ± 0.1 220.6 ± 27.2 26.8 88 October 3.5 ± 0.1 218.0 ± 24.5 27.1 86 November 3.6 ± 0.2 150.5 ± 23.4 28.4 81 December 3.2 ± 0.1 116.6 ± 6.0 29.2 81 January 2005 3.5 ± 0.2 105.0 ± 2.8 29.8 79

4 Chromolaena odorata Newsletter 17, December 2008

20 RESULTS AND DISCUSSION 18 y = 0.0361x + 0.0082 16 R2 = 0.9979 Occurrence of Aphis spiraecola -2 Over the sampling period, a mean of 4.22 C. odorata plants 14 and 209 A. spiraecola per m 2 were present in the quadrats 12 sampled (Table 1). Hermoso de Mendoza et al . (2006) 10 reported the Economic Threshold and Economic Injury Level 8 2 of this aphid on Citrus clementina to be 322 and 370 per m 6 respectively, while Hall et al . (1972) reported that the number No. mottled leaves leaves m No. mottled 4 of this aphid per C. odorata plant varied greatly, from 16 in low infestations to over 150 during a severe attack. Since 2 A. spiraecola has long been recognized as a pest of crops and 0 a vector of many plant diseases (Pirone, 1978), its abundance 0 100 200 300 400 500 600 and distribution on C. odorata might lead to the infestation of No. A. spiraecola m-2 citrus and other crops in nearby plantations or farms, and Figure 2. Relationship between Aphis spiraecola population and subsequently result in a pest outbreak. The percentage of mottled Chromolaena odorata leaves. aphid-infested C. odorata plants was usually higher compared to non-infested plants (Fig. 1). 70

Aphis spiraecola was present on every sampling occasion of 60 y = 0.1222x - 8.498 the study, agreeing with Pfeiffer (1991), who reported that the R2 = 0.9265 -2 50 aphid breeds throughout the year. The population was highest m during the first sample (August) and declined over the five 40 months sampled thereafter. This decrease in the aphid population over time was negatively correlated with 30 2 africana C. temperature (y = -0.0126x + 30.386, R = 0.8704, P < 0.001) 20 and positively correlated with relative humidity (y = 0.0313x No. + 77.565, R 2 = 0.771, P < 0.001). An understanding of the 10 role and interaction of these climatic factors assist in pest 0 management decision-making. The occurrence of 0 100 200 300 400 500 600 A. spiraecola throughout the year is of concern in crop -2 systems as it can cause year-round damage to crops. In No. A. spiraecola m addition, high populations of the aphid may cause severe Figure 3. Relationship between Aphis spiraecola and Cremato- attack to crops, resulting in crop loss and food insecurity in a gaster africana in Chromolaena odorata -infested areas. region already suffering from food scarcity. 2007). Both nymphs and adults of A. spiraecola fed on the 80 young, succulent terminal shoot-tips and their feeding activity % infested always resulted in the mottling of C. odorata leaves. 70 % non-infested Oigiangbe et al . (2007) found similar results in a study of the 60 association between some insects and the weed. As high

-2 populations of A. spiraecola cause curling of citrus foliage m 50 and can also stunt tree growth, especially on young trees 40 (Pfeiffer et al ., 1989), the widespread occurrence of C. odorata in plantations raises the fear that A. spiraecola 30 may become an important pest or vector of some tree crop C. odorata diseases in Nigeria (Uyi, 2005). % % 20

10 There was a significant (P < 0.001) positive linear relation- 0 ship between A. spiraecola and C. africana (Fig. 3) . This ant Aug Sept Oct Nov Dec Jan species was observed on the aphid-infested parts of plants , Month feeding on honeydew produced by the aphids. The relation- ship between ants and homopterans is mutualistic with the Figure 1. Percentage of aphid-infested and non-infested homopterans providing energy-rich honeydew for the ants Chromolaena odorata plants per m 2. which in turn protects and transports the former (Nixon, 1951; Strickland, 1951). Relationship between Aphis spiraecola and Chromolaena odorata The need to control Chromolaena odorata in Nigeria There was a significant (P < 0.001) correlation between The above results show that C. odorata acts as a reservoir for numbers of A. spiraecola and mottled C. odorata leaves A. spiraecola . Since C. odorata is extremely widespread and (Fig. 2), indicating that the mottled appearance is caused by abundant, it is possible that it may allow A. spiraecola to A. spiraecola . As the population of A. spiraecola increases, become a serious pest of crops in Nigeria and other countries the number of aphid-infested C. odorata plants and the in the West African sub-region where C. odorata is invasive, number of mottled leaves also increases (Oigiangbe et al ., hence there is a need to establish a control and management

5 Chromolaena odorata Newsletter 17, December 2008 programme for C. odorata in Nigeria and elsewhere. Erasmus, D.J. 1985. Achene biology and the chemical control Chromolaena odorata has also been reported to harbour of Chromolaena odorata . Unpubl. Ph.D. Thesis, Department Z. variegatus , an important pest of many crops in the sub- of Botany, University of Natal, South Africa 379pp. region (Uyi, 2005). Hall, J.B., Kumar, R. and Enti, K.A. 1972. The obnoxious Apart from C. odorata harbouring A. spiraecola , which is a weed odoratum (Compositae) in Ghana. Ghana potential risk to crops, the weed is known to decrease the Journal of Agricultural Sciences 5: 75-78. carrying capacity and species diversity in grassland and forests (Macdonald, 1984; Erasmus, 1985; Byford-Jones, Hammond, W.N.O. 1992. Survey and sampling cassava 1989) and it also impacts negatively on agricultural mealybug and its natural enemy population. In: Markham, productivity (Timbilla and Braimah, 2000). Considering that R.H, Wodageneh, A., Agboola, S. (eds). Biological Control the problem of C. odorata is too ecologically and Manual, Volume II: Case Studies of Biological Control in economically significant to be ignored, an integrated Africa . IITA Biological Control Centre for Africa, Cotonou, approach is needed for the control and management of the Republic of Benin. pp. 48-69. weed. Uyi (2008) recommended the release of large numbers of the leaf feeder Pareuchaetes pseudoinsulata Rego Barros Hermoso de Mendoza, A., Arouni, R, Belluire, B., Carbonell, (Lepidoptera: Arctiidae) and other agents such as the stem- E.A. and Perez-Panadez, J. 2006. Intervention threshold for galling fly Macquart (Diptera: Aphis spiraecola (Hemiptera: Aphididae) on Citrus Tephritidae) that can attack the vegetative parts of the weed clementina . Journal of Economic Entomology 99: 1273-1279. to reduce seedling establishment and the density of C. odorata stands. NIFOR initiated and funded the original Ivens, G. W. 1974. The problem of Eupatorium odoratum L. research on biological control of C. odorata by the Common- in Nigeria. Pest Articles and News Summaries 20: 76-82. wealth Institute for Biological Control in Trinidad in the 1960s, and two biocontrol agents, P. pseudoinsulata and the Julien, M.H. and Griffiths, M.W. 1998. Biological Control of flower feeding Apion brunneonigrum Beguin-Billecoq Weeds: a World Catalogue of Agents and their Target Weeds, (Coleoptera: Curculionidae), were released in Nigeria in the 4th edn . Wallingford, UK: CAB International Publishing. early 1970s. However, neither established and no further biocontrol efforts have been undertaken since (Julien and Kranz, J., Schumutterer, H. and Koch, W. 1977. Diseases, Griffiths, 1998). The spread and distribution of the weed Pests and Weeds in Tropical Crops . Verlag Paul Parey, poses serious problems to agriculture and biodiversity in the Berlin. 489 pp. southern part of Nigeria. Therefore, it is recommended that a biological control programme using P. pseudoinsulata and Macdonald, I.A.W. 1984. Infiltration of dreaded weed alarms C. connexa should be initiated to tackle this invasive weed. experts. Custos 13: 33-35.

In conclusion, the abundance and occurrence of A. spiraecola Nixon, G.E.J. 1951. The Association of Ants with Aphids and on the ever-increasing C. odorata infestations pose a potential Coccids . Commonwealth Institute of Entomology. London. threat to citrus plantations, eggplant and other crops, which 35 pp. are suitable hosts for this insect. Biological control and management of C. odorata is highly recommended, because it Oigiangbe, O.N., Uyi, O., Aisagbonhi, C.I. and Igbinosa, I.B. will help reduce the pestilence of the known crop pests 2007. Ecological roles of insects on Siam weed, A. spiraecola and Z. variegatus . Chromolaena odorata (L.). Advances in Science and Technology 1: 108-115. ACKNOWLEDGMENTS Pfeiffer, D.G. 1991. Biology and management of aphids on The authors are thankful to Prof. D.A. Enobakhare of the apple. In: Williams, K. (ed) New Directions in Tree Fruits Department of Crop Science, University of Benin, Benin City Pest Management . Good Fruit Grower, Yakima. 214 pp. for his help in identifying the aphid. Crematogaster africana was identified at the Entomology Museum of the Department Pfeiffer, D.G., Brown, M.W. and Varn, M.W. 1989. of Zoology, University of Ibadan, Nigeria. Incidence of spirea aphid (Homoptera: Aphididae) in apple orchards in Virginia, West Virginia and Maryland. Journal of REFERENCES Entomological Science 24: 145-149.

Boppré, M. 1991. A non-nutritional relationship of Zonocerus Pirone, P.P. 1978. Diseases and Pests of Ornamental Plants . (Orthoptera) to Chromolaena odorata () and Wiley Interscience Publication. New York. 244 pp. implications for weed control. In: Muniappans, R. and Ferrar, P. (eds.) Proceedings of the Second International Workshop Strickland, A.H. 1951. The entomology of swollen shoot of on Biological Control of Chromolaena odorata. February cacao I: the insect species involved with notes on their 1991. Biotrop Special Publication 44, Bogor, Indonesia. pp. biology. Bulletin of Entomological Research 41: 725-748. 154 – 155. Timbilla, J.A and Braimah, H. 2000. Establishment, spread Byford-Jones, C. 1989. Watch out for this alien. Farmers and impact of Pareuchaetes pseudoinsulata (Lepidoptera: Weekly May 12: 13-15. Arctiidae), an exotic predator of the Siam weed,

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Chromolaena odorata (Asteraceae: ) in Ghana. Unpubl. B.Sc Thesis, Ambrose Alli University, Ekpoma, In: Spencer, N.R. (ed). Proceedings of the X International Nigeria. 66 pp. Symposium on Biological Control of Weeds , July 1999, Montana State University, Bozeman, USA, pp. 105-111. Uyi, O. 2008. Evaluation of the biological control of Chromolaena odorata (L.) (Asteraceae: Eupatorieae) by Uyi, O. 2005. Prospecting for the biocontrol agents of the Pareuchaetes pseudoinsulata (Lepidoptera: Arctiidae) in Siam weed, Chromolaena odorata (L.) (Asteraceae: southern Ghana. Unpubl. M.Phil. Thesis, University of Eupatorieae) in the undergrowth of an oil palm plantation. Ghana, Legon. 113 pp.

7 Chromolaena odorata Newsletter 17, December 2008

Recommendations of the Seventh International Workshop on Biological Control and Management of Chromolaena odorata and Mikania micrantha , Taiwan, 12-15 September 2006

1. Governments of all countries affected by chromolaena are encouraged to consider the introduction of Cecidochares connexa. 2. Governments of all countries affected by chromolaena and mikania are encouraged to send representatives to the next workshop. 3. Regional organizations e.g. SPC and countries affected to produce public awareness material on chromolaena for identification and containment and control measures. 4. Countries should increase awareness of, and promote, biological control of weeds and its benefits.

About this newsletter…

The Chromolaena odorata Newsletter is published at irregular intervals. To contribute articles pertaining to biological control and management of C. odorata , please contact C. Zachariades, ARC-PPRI, Private Bag X6006, Hilton 3245, South Africa. E-mail: [email protected]

This newsletter is produced at the Agricultural Research Council (ARC), South Africa, in association with the Chromolaena odorata Working Group of the International Organization of Biological Control of Noxious Animals and Plants (IOBC).

Trade names of products are used to simplify the information. No endorsement of named products is intended.

Any opinion, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the ARC or the IOBC.

ISSN 2071-274X

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