Proceedings of the Eighth International Workshop on Biological Control and Management of Chromolaena odorata and other Eupatorieae, Nairobi, Kenya, 1-2 November 2010. Zachariades C, Strathie LW, Day MD, Muniappan R (eds) ARC-PPRI, Pretoria (2013) pp 20-27

Recent spread and new records of Chromolaena odorata in Africa

Costas Zachariades1,4*, Susan Janse van Rensburg2,5 and Arne B.R. Witt3

1Agricultural Research Council, Plant Protection Research Institute, Private Bag X6006, Hilton, 3245 South Africa 2Grumeti Fund, PO Box 65, Mugumu, Tanzania 3CABI Africa, ICRAF Complex, United Nations Avenue, Gigiri, Nairobi, Kenya 4School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa 5Current address: South African Environmental Observation Network, PO Box 13053, Cascades, 3202 South Africa *Corresponding author: [email protected]

Two biotypes of Chromolaena odorata (L.) King & Robinson (Asteraceae: Eupatorieae) are invading sub-Saharan Africa. One (the Asian/West African biotype) is spreading from tropical West Africa and the other (the southern African biotype) from south-eastern Africa. The area invaded by the former is much greater than that invaded by the latter. Recent infestations of the Asian/West African C. odorata biotype have been confirmed from north-western Angola, the eastern Democratic Republic of the Congo, eastern Uganda, eastern Rwanda, south-western Kenya and north-western Tanzania. The infestation in north-western Tanzania, east of Lake Victoria, is large and dense and appears isolated from similar infestations, probably representing a discrete introduction. Unconfirmed reports (and therefore of unknown biotype) from southern Malawi, north-western Mozambique and north-eastern Tanzania need to be investigated. While the high altitude of regions of East Africa is expected to slow the rate of spread of C. odorata in some areas, the Rift Valley and the eastern coastline are highly suited climatically to the Asian/West African biotype and it is probably only a matter of time before these regions become invaded. It is likely that as the Asian/West African biotype spreads south, it will eventually become sympatric with the southern African biotype as it spreads north. However, it is unknown how these two biotypes will interact. It is recommended that an identification kit for C. odorata be developed and distributed, that early awareness and control programmes be developed, and that biological control be considered at an early stage of invasion in these areas.

KEYWORDS: Angola; East African coast; invasive alien plant species; Kenya; Malawi; northern Mozambique; Rift Valley; Rwanda; Tanzania; Uganda

INTRODUCTION morphology and aspects of its biology from the first (Zachariades et al. 2009). Strong genetic Two independent introductions of different evidence indicates that this biotype originates in biotypes of Chromolaena odorata (L.) King & Jamaica or Cuba (Paterson and Zachariades Robinson (Asteraceae: Eupatorieae) have been 2013). Both have become highly invasive and made into Africa. One biotype was probably damaging to agricultural and natural systems. introduced from Asia, where it was already a widespread invader, into West Africa (Nigeria The distribution of C. odorata in Africa was in the 1930s or early 1940s and possibly Côte most recently updated in Zachariades et al. d’Ivoire in the 1950s) (Zachariades et al. 2009). (2009). The biotype introduced into West The second biotype was first recorded as Africa, named the Asian/West African (A/WA) naturalised in South Africa in 1947 biotype, has since spread to the west as far as (Zachariades et al. 2011), and differs in the Gambia, to the north into southern Burkina

20 Zachariades et al.: New chromolaena records for Africa

Faso and Chad, south-east as far as northern mosaics), C. odorata was recorded as forming a Angola, and east through the Democratic dense, tall infestation on either side of much of Republic of the Congo (DRC) (Gautier 1992; the 280km stretch of road and across all fallow Zachariades et al. 2009). The weed has and abandoned farmlands (B.J. Huntley, pers. probably reached its northerly limit in West comm. to G. Preston, 2010) (Table 1). Africa, as it has invaded the savannas adjacent to the arid Sahel region. The biotype introduced Surveys to the west as far as N’dalatando also into South Africa, named the southern African revealed the presence of C. odorata (Table 1). It (SA) biotype, has spread into much of the is likely that this is causing a high cost to the subtropical eastern parts of this country as well rural economy, now moving from food cash as into Swaziland and southern Mozambique. A crops to charcoal production. As a result, people specimen of C. odorata collected in northern are likely to become more dependent on aid Zimbabwe in the 1960s (Gautier 1992) appears from the World Food Programme (B.J. Huntley, to be of the Asian/West African biotype pers. comm. to G. Preston, 2010). (Zachariades et al. 2009), as is the weed on Mauritius (ARC-PPRI, unpubl.). Democratic Republic of the Congo Although the A/WA biotype of C. odorata is McFadyen and Skarratt (1996) and Kriticos et reported as having been present in the DRC al. (2005) showed that much of sub-Saharan since the mid-1970s (Gautier 1992), it was Africa, excluding very arid regions and those understood that infestations were restricted to south of 30°S, but including eastern the western parts of this large country. Recent Madagascar, were climatically suitable for C. reports of dense infestations of the weed, odorata. Kriticos et al. (2005) also showed that producing large numbers of seeds, in the east of the invasion of the SA C. odorata biotype the country, fairly close to the border with extended into cooler regions than would be Burundi (Namoya) and Uganda (Ituri) are predicted for the A/WA biotype. Thus the A/ therefore cause for concern (Table 1). They WA biotype of the weed, and probably the SA probably indicate that C. odorata has spread biotype, have not achieved their full invasive across the country from west to east, through ranges in Africa. dispersal of the seeds through wind, water and/ or human and mechanised traffic. Although This paper lists and describes recent confirmed both the Namoya and Ituri infestations are close infestations of C. odorata since Zachariades et to the upper limits of the reported altitudinal al. (2009), and discusses where the weed is range of C. odorata distribution, the dense likely to be already and which areas it may nature and high seed production, of the Namoya spread into, as well as giving recommendations infestation at least, imply that it is not marginal as to obtaining further locality records and habitat for C. odorata. control of incipient infestations. PREVIOUSLY UNCONFIRMED NEW LOCALITY RECORDS FROM COUNTRY RECORDS NOW COUNTRIES WHERE CHROMOLAENA CONFIRMED ODORATA WAS PREVIOUSLY CONFIRMED To confirm previous anecdotal reports of C. odorata or any other weed being present in a Angola country, it is desirable to obtain photographic The A/WA biotype has previously been records and preferably non-sterile herbarium recorded in northern Angola (Hoevers & specimens. This is illustrated by the M’boob 1996) and probably arrived in the late misidentification of Ageratina adenophora 1970s (see Gautier 1992). However, during (Spreng.) King & Robinson (Asteraceae: recent vegetation surveys conducted between Eupatorieae) as C. odorata in Zambia. This was Luanda and Uige to the north-west, through the only resolved once herbarium specimens had Dembos forests (forest and forest-savanna been identified (ARC-PPRI, unpubl. data).

21 Eighth International Workshop on Biological Control and Management of Chromolaena odorata and other Eupatorieae

Tanzania In 2009 and 2010, a large area of infestation of

the A/WA biotype was confirmed to be present

near the eastern shores of Lake Victoria (Table 2). Some of the edges and interior of a polygon of about 80km by 70km were mapped, and

infestations varied from dense to sparse within Observer(s) Huntley B.J. Huntley B.J. Bytebier, B. Luke W.R.Q. 2749) (EA Luke, W.R.Q. Bujo F. (+Sight 097 Record) this area. The whole area is at an altitude of

>1000m above sea level. A recent (2013) survey by one of us (A.B.R. Witt) indicated that

along along

this infestation extends along road B6 only to

about 50km south of Musoma, in an area where the Serengeti extends almost to Lake Victoria. Interestingly, no C. odorata was found C. odorata C. anywhere to the south-west or west of this (i.e.

the southern or western shores of Lake Victoria, within north-western Tanzania, and up to the borders with Uganda and Rwanda). This indicates that the infestation east of the south- eastern shores of Lake Victoria is isolated, and Description ofinfestation Description increase of Huge on areas moist the in theall roads toN’dalatando. the road road along infestations denseTall, inandfields. goldmine. artisanal Open, forest. secondary open Disturbed, itself established have Seems to invasive; but recently very is fairly site. dense asNamoya notas non-contiguous with C. odorata infestations in the DRC. It may represent a discrete

introduction from further west in Africa. North- west of Musoma, thick infestations of C. odorata stretch along the B6 as far north as Sirari, 2km from the border with Kenya, after which they reduce considerably.

An unconfirmed sighting of C. odorata on the

had previously been recorded, but for which new data are available. are data new which butfor been recorded, previously had Mtibwa Sugar Estate (6°10.300’S 37°38.267’E,

Localitydescription Luanda between Road andN’dalatando along forests Dembos and Luanda between road Uige Prov.,Namoya, Maniema topof Mwendamboko Hill District Oriental, Province of Bunia, westIturi, Site Mine Mongbwalu

366m above sea level), towards the north-east

of Tanzania, north-west of Dar es Salaam, was reported in 2004 (Q. Mann, pers. comm. 2004).

Year 2009 2010 ix.2008 x.2010 Given the links between this sugar company and

the Mauritian sugar industry (e.g. http://

850 935 www.mrc.org.mu/P_SE01.htm), it is possible - - that this easterly outlier originated in Mauritius.

Alt. (m) Alt. 50 50 960 1,225 Chromolaena odorata Chromolaena

Kenya The first confirmed records of C. odorata in Kenya (biotype not specified, but most likely to

37.0'S15

14.07'E 14.07'E 54.40'E 14.07'E



  

be A/WA) were from the Nucleus Estates of the Mumias Sugar Company (0°21.792’N 34° 30.250’E, 1,293m asl) in 2006 (Q. Mann, pers. comm. to CZ, 2007). The presence of C.

50.30'S 13 50.30'S 14 17.83'S 13 50.30'S

  

03.0'E (Uige) 03.0'E odorata at Mumias was also confirmed by B. le Coordinates 8 to (Luanda) 9 (N’dalatando) 8 7 to (Luanda)  27°32.90'E 4°00.12'S 30°02.35’E 1°56.66’N Ru (pers. comm. to D. Conlong, 2007). More

Countries in Africa in which in Africa in Countries

recently, another infestation of C. odorata (A/

WA biotype) has been confirmed as present along the border with Tanzania, near the

Country Angola DRC

Table 1.Table Kenyan shores of Lake Victoria (Table 2),

22 Zachariades et al.: New chromolaena records for Africa which are contiguous with that reported in Zachariades, 2005) observed C. odorata at Tete Tanzania. Some small roadside infestations (16°10′S 33°36′E, 130m asl) in the north-west have recently (2013) been noted along the A1 of Mozambique. The infestation was sparse, road from Tanzania at Isibania (Table 2), but consisting of individual plants rather than this area is under intensive agriculture, which thickets. The biotype of this infestation is would result in C. odorata being cleared. unknown but would presumably be the same as that in southern Malawi. NEW COUNTRY RECORDS The single specimen (U 0103502) of C. odorata Rwanda (apparently A/WA biotype) collected in The presence of C. odorata (biotype unknown, Zimbabwe in 1967 (Gautier 1992) was from the but probably A/WA) was first recorded in 2003 vicinity of Chinhoyi (previously Sinoia) (17° at the entrance to Akagera National Park, in the 22'S 30°12'E) at an altitude of 1,600 m, within east of the country (Table 2). At that time it was the watershed of the Zambezi River, upstream not widespread, although it was subsequently from Tete. Thus the two infestations may be seen in the north of this national park (P. linked, although a recent survey for invasive Goodman, pers. comm. 2011). However, a alien plants in Zimbabwe failed to find C. recent (2013) countrywide survey by one of us odorata, even though it included the Chinhoyi (A.B.R. Witt) did not result in any new records region and the north-eastern border near Tete of C. odorata, probably because much of the (Sheppard et al. 2012). If the unconfirmed country is now under intensive agriculture. infestation in north-western Mozambique is of the A/WA biotype, Mozambique would Uganda currently be the only country worldwide to have An infestation of the weed (A/WA biotype) was infestations of both the A/WA and the SA found 5km west of Busia, near the border with biotype. Kenya, in 2010 (Table 2). Subsequently other infestations have apparently been found to the Senegal west of this locality, but locality records are not Chromolaena odorata plants were observed in available. Extensive surveys undertaken in 2008 Senegal in 2005 (Q. Mann, pers. comm., 2007) -2009 in the west of Uganda, on the DRC but the extent and density of the infestation border, failed to find C. odorata (A.B.R. Witt, there is unknown. unpubl. data). Kriticos et al. (2005) indicated that most or all of Uganda is highly climatically Countries in which C. odorata is assumed to suitable for C. odorata. be present

UNCONFIRMED REPORTS Guinea Bissau, Burundi No records or anecdotal reports have been Malawi received from these countries. However, given An unconfirmed report of C. odorata as being that they lie between countries in which C. common along the Shire River (about 14°47’S odorata has been confirmed and are climatically 35°16’E, 500m to 17°07’S 35°18’E, 50m asl), suited to the weed, it is likely that C. odorata is Blantyre (15°47'S 35°0’E, 1,030m asl) and already present. Zomba (15°23′S 35°20′E, 961m asl) areas of southern Malawi (J. Findlay, pers. comm. to C. Future spread Zachariades, 2005) is credible as it is in the The spread of C. odorata in an easterly same region as Tete, in north-western direction in Kenya and Tanzania will possibly Mozambique (see below). The biotype of these be slowed by the higher-lying massifs that form infestations is unknown. a north-south ridge down these two countries. Kriticos et al. (2005) indicated that this region North-western Mozambique was less suitable climatically than the Rift In the early 2000s, J. Findlay (pers. comm. to C. Valley and the eastern coastline, which are both

23 Eighth International Workshop on Biological Control and Management of Chromolaena odorata and other Eupatorieae

Observer(s) Witt A.B.R. Witt A.B.R. P.S.Goodman Rensburg van S.J. Witt A.B.R.

Description ofinfestation Description growing plants individual Aboutfive River. of Mgodi onedge alongside road A1 along infestations Smallroadside given) (coordinates of Isibania north Savanna, Leaf Compound Mesic Habitat: Infestation: mm. of 900 withrainfall each. ha of 0.25 clumps severallarge B6 road along Densestinfestations some Tarime; and Kukirango between and Mugumu between infestations Kukirango; and Nyamuswa Marasimoche, between and Marasimoche survey aerial unconfirmed some alsoadded Nyakitono thisoutside points number of A sightings. alsowere recorded. polygon onalongside road mainly Infestations Forest. edge of Busitema

inAfrica.

Localitydescription border with Near Kenya SW Tanzania, Tanzania, with Border SWKenya Akagera to Entrance (500m Park National accuracy) Mugumu Nyamuswa Kukirango Tarime Marasomoche of west 5km Busia,

Chromolaena odorata Chromolaena

Date xi.2010 v.2013 ii.2003 2009, 2010 2010

Alt. (m) Alt. 1,412 1,650 1,388 1,530 1,380 1,255 1,362 1,241 1,169 1,172 1,134

Coordinates 34°37.92’E 1°09.77’S 34°28.69ʹE 1°14.17ʹS 30°41.61'E 1°53.02'S Polygon: 34°40.37'E 1°50.38'S 34°01.03’E 1°54.13’S 33°51.58’E 1°45.97’S 34°21.78’E 1°20.40’S 34°33.78’E 1°35.03’S 33°58.24'E 0°30.89'N 33°58.74'E 0°30.41'N 33°58.97'E 0°31.83'N

Recent confirmed country records of country confirmed Recent

Country Kenya Rwanda Tanzania Uganda

Table 2.Table

24 Zachariades et al.: New chromolaena records for Africa predicted to be highly suited to C. odorata. is likely more fire-tolerant, resprouting from the Although the weed has not been reported from base of the plant (Zachariades et al. 2009). Madagascar as yet, it may already be there. Therefore in frequently-burned grassland the A/ Small infestations of probably Mikania WA biotype may outcompete the SA biotype. micrantha Kunth. (Asteraceae: Eupatorieae) were recorded at several sites between CONCLUSIONS AND Fianarantsoa and Manakara in 2008 (C. RECOMMENDATIONS Zachariades, unpubl.). The only other country in the region where M. micrantha is already It appears certain that the presence of C. known to be present is Mauritius. Thus it is odorata in East Africa in particular, has been possible that C. odorata may be introduced into substantially under-reported over the past two to Madagascar from there. Chromolaena odorata three decades. Dense infestations are already has not been recorded on other climatically present in the eastern DRC and western suitable Indian Ocean islands such as the Tanzania, with scattered plants reported Seychelles (Kueffer and Vos 2004), the elsewhere in the region. Unconfirmed reports of Comoros (Vos 2004) and Réunion (Kueffer and the plant as being widespread and common in Lavergne 2004). A recent floral inventory of north-western Mozambique and southern São Tomé and Príncipe (Figueiredo et al. 2011) Malawi need to be followed up with some does not list C. odorata, despite the islands’ urgency. Such infestations would represent the relatively proximity (just over 200km) to Gabon most southerly of the A/WA biotype on the and their expected susceptibility to invasion by African continent. The presence of C. odorata C. odorata (Gautier 1992). in north-eastern Tanzania would also be of concern because it represents an incursion along According to Kriticos et al. (2005), the A/WA the eastern African coastline, a highly biotype can be expected to reach its southern climatically suitable region for the weed. climatic limits along the coast of southern Mozambique. The northern climatic tolerances At the 8th IOBC International Workshop on of the SA biotype (i.e. how far north into Biological Control and Management of tropical Africa it may spread) are currently Chromolaena odorata and other Eupatorieae, unknown but it is already present in the held in Nairobi, Kenya in November 2010, the southern Mozambican coastal region. Thus it is need for an identification kit for C. odorata was likely that the two biotypes will become highlighted (Anonymous 2011). This is sympatric at least to a small extent. It is not particularly needed for distribution to known how these two biotypes will interact if agricultural and conservation personnel working they come into contact. C. odorata has been in the field in regions of Africa in which C. shown to be apomictic but is also visited by odorata has not been definitely recorded but pollinators (Zachariades et al. 2009). Therefore, which are climatically suitable. In order to it is possible that there may be some genetic confirm suspected sightings of C. odorata, flow between the two biotypes. It is likely that personnel should take photographs and some of the biological control agents preferably herbarium specimens. Although non- established on the SA biotype will attack the A/ sterile specimens are preferable, if the plants are WA biotype. However, Cecidochares connexa not flowering, then sterile specimens are still Macquart (Diptera: Tephritidae), the stem- useful. galling fly that has been used with great success in Papua New Guinea (Day et al., this The workshop also adopted several official proceedings) and has been introduced into Côte recommendations (this proceedings), some of d’Ivoire (Zachariades 2011), has been shown which are relevant to detection of spread and not to attack the SA biotype (Zachariades et al. early control of C. odorata in Africa. These 1999). One biotype may show a competitive included encouraging workshop participants in advantage over the other under various Africa to create awareness and capacity- circumstances. For example, the A/WA biotype building and inform their respective

25 Eighth International Workshop on Biological Control and Management of Chromolaena odorata and other Eupatorieae government officials and other interested parties Guam, USA, Publication 202:1-5 of the need to conduct C. odorata distribution surveys and of the urgency for respective Kriticos DJ, Yonow T, McFadyen RE (2005) governments to initiate measures to tackle C. The potential distribution of Chromolaena odorata immediately, using an integrated odorata (Siam weed) in relation to climate. approach. Such control measures should include Weed Res 45:246-254 the use of the natural enemies Pareuchaetes pseudoinsulata Rego Barros (Lepidoptera: Kueffer C, Lavergne C (2004) Case studies on Arctiidae) and C. connexa as biological control the status of invasive woody plant species in the agents of C. odorata. western Indian Ocean. 4. Réunion. Forest Health & Biosecurity Working Papers FBS/4- ACKNOWLEDGEMENTS 4E. Forestry Department, Food and Agriculture Organization of the United Nations, Rome, Italy The first author thanks the ARC and Working for Water programmes for funding and Kueffer C, Vos P (2004) Case studies on the permission to attend the Kenya workshop. Dr B. status of invasive woody plant species in the Bytebier, Mr W.R.Q. Luke and Dr P.S. western Indian Ocean. 5. Seychelles. Forest Goodman are thanked for permission to use Health & Biosecurity Working Papers FBS/4- unpublished locality records of C. odorata. Dr 5E. Forestry Department, Food and Agriculture B.J. Huntley, Mr Q. Mann and Mr J. Findlay are Organization of the United Nations, Rome, Italy thanked for information on sightings of C. odorata. Michael Day provided useful McFadyen R, Skarratt B (1996) Potential comments on a draft of this document. distribution of Chromolaena odorata (Siam Weed) in Australia, Africa, and Oceania. Agr REFERENCES Ecosyst Environment 59:89-96

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27