Records of Homoptera Auchenorrhyncha from palms and associations with disease in coconuts
M. R. WILSON (1)
Summary. - The leafhopper, planthopper. treehopper and cicada species (Homoptera : Auchenorrhyncha) associated " ·it h palms have been reviewed. Nine fulgoroid families ha\e been found on palms and five: Delphacidae. Tropiduchidae. lss id ae, Lophopidae, and Flatidae are represented by species that breed on palms. Several speci es of Cicadellidae and one species of !\ lembracidae a re also known to breed on palms. !\!any Cixiidae and Derbidae whose nymphs are found underground or in rotten wood, feed on palms as adul1s. Direct damage to date palms is caused by the feeding of the tropiduchid 0111111atissus binotatus lybirns de Bergevin and the lophopid Zophiuma lobulata Ghauri on coconuts as well a< indi rect damage by the growt h of mould on the honeydew produced by 0. b. lybicus. Auchenorrhyncha are currently under investigation as vec10rs of a number of palm disorders. among them lethal yellowing. A summary of di seases that affect coconut is gi,·en. Vector species have been found among those species that are not known to complete their development on palms but which feed frequently from palm foliage, the most notable being the cixiid M.1'11dus crudus \'an Duzee, the vector of palm lethal yellowing in southern LiSA and the Caribbean.
INTRODUCTIO:\' I. - AUCHENORRHYi\CHA SPECIES ON PALMS Palms are a11acked by a considerable array of insects and Lepesme [19~7] reviewed and li sted all those recorded, Table I is a summary of the information given in Wilson pests and non-pests, from palms. Jn general, Hemiptera [1987) and further information wil l be found th ere. haYe not been considered important pests of palms with Evaluation of the records given in Lepesme and recent exceptions such as Pseudotheraptus wayi Brown (Heterop surveys has been made. Differentiation has been made tera : Coreidae) in Africa and A111blypelta spp. between species breeding on palms and those found (Heteroptera : Coreidae) in the Pacific Islands, both casually on palms feeding as adults but whose nymphal attacking coconuts [see Lever, 1969]. Among the stages are found elsewhere. For instance many Cixiidae Auchenorrhyncha (l eafhoppers, plamhoppers, ~-= and Derbidae whose nymphs are found underground or in ~. cicadas, etc.) only Ommarissus binotatus var rotten wood may be common on palms as adults. The lybicus Bergevin (Tropiduchidae) has been noted as a major pest species, both as plant disease vectors and for serious pest, of date palms in the /\ liddle East. Lever the effects of direct feeding, occur within the Fulgoroidea [1 969) does not include any Auchenorrhyncha species as (planthopper) families. Most of the pests of palms have pests of coconut. come from species only casually associated with palms .i.e. Increasingly, however, Hemiptera are implicated in the by feeding only but some species that breed on palms may transmission to palms of plant disease pathogens such as also cause damage. What might be considered « hopper lethal yellowing. Jn the Heteroptera, species of pentatomid burn » has been caused by the feeding of the lophopid z. bug are now known to transmit flagellate (Phytomonas) lobulata in Papua New Guinea on coconuts. The tropidu disease to palms in S. America [Desmier de Chenon, chid 0. b. lybicus is a major date pest in the Middle East 1984] ; « Hartrot » of coconuts [Louise et al., 1986) and because of its feeding and because of the honeydew it « /\larchitez sorpresiva » of oil-palm [Dolling, 1984, produces. Nine' families are represented on palms, with Perthuis et al., 1985] are spread by Lincus spp. In India a species in five families breeding. The total number of tingid , Srephaniris typicus Distant is the vector of a species involved is relatively small and further collecting coconut root wilt [Joseph et al., 1972]. will certainly increase the records of palm-associated Among the Auchenorrhyncha, Cixiidae, Delphacidae species. Records of other Auchenorrhyncha families are and Cicadellidae species are now known to transmit disease far less ; only one membracid treehopper, ldioderma pathogens to coconut, and surveys, are being conducted virescens is reported as breeding on palms, two cicada - that may implicate further species. Records of palm species Diceroprocta apache and Proarna hilaris are associated Auchenorrhyncha have been reviewed by recorded as minor pests. Compared with the Fulgoroid Wilso n [1987]. This paper is a summary of that informa families rather few cicadellids (l eafhoppers) are presently tion with emphasis on associations of Auchenorrhyncha known from palms. This too must, surely. be under- with coconut disease. The starting point in the literature recording. search was the excellent compilation of Lepesme [ 1947] who listed many species of Auchenorrhyncha recorded from palms. II. - DISEASES OF COCONUT
Auchenorrhyncha have been implicated or suspected as
(!) CAB Inierna1ional lnstilute of Entomology, 56 Queen's Gale, the vectors of a number of di seases affecting coconuts. London, SW? 5JR (Great-Elritain). Some of the disease syndromes described here e.g. lethal Okagineu\, \ "o l. 43, 11 ° 6 - .Juin 1988
TABLE I. - Summary of records of Auchenorrh~ ncha asso<:iatrd with palms. Emphasis has been placed on those species breeding on palms and on tho~c indi<:ated as disease nctors
Full dclailli and rdcrences appear in \\ i1'011 I 19871
rRes11111e des rece11se111en1s d'.411che11orrhvnques associes avec fes paf111ier.1·. Une arre11rio11 parricufiere esr porree sur fes especes qui se reprod11ise11r sur fes pafmiers er sur ceffes considerees co111111e ham des agems 1·ecreurs)
Pour de pil11 a11111ln re111ei~neme111' er dev rcfl'ft'llC~'- 1·01r ll'il.wn (1987/
Family / species Country/ region Host piant(s) rFa111illel espece1 rPays ! region) r Plantefs) h6refs))
Flatidae Ormenaria ruf(fascia (Walker) .. southern USA, Jamaica Sabal pal111e110. rSud des USA) Uamaique) Latanaria lomaroides Psenoflata bre1·is Van Duzee•• Jamaica coconut rcocotier)
Delphacidae Sesodryas antiope Fennah** Seychelles. Mascarenes. Africa Tanzania coconut Sogatodes c11ba1111s (Cra\\ ford)• W. Africa fAjrique de l'Ouesl) coconut (cocotier) So?ate/la kolophon (Kirkaldy)- W. Africa coconut
Tropiduchidae .4thestia chariclo Fennah** Mexico fMexique) Chamaedorea sp. Ka/litaxila apicalis (t\ lelichar)** Philippines coconut Tambinia verticalis (Distant)** Africa : Tanzania coconut fcocorier) Ommatissus binotatus Fieber•• Spain (Espagne) Chamaerops humi/is 0. b. lybicus de Bergevin•• t\liddle East (Moyen-Oriem) date palm (palmier dottier) 0. rwnidulus Linnavuori** Sudan fSoudan) Phoenix sp.
l ssi ~L1e Asarcopus palmarum Hon·ath** Middle East, USA (intr.) date palm (palmier dottier) Colpoptera ?ele1·ans Walker .. Jamaica coconut
Lophopidae Zophiuma lobulata Ghauri•• Papua New Guinea coconut Paine/la sim111011dsi Muir•• Solomon Islands coconut (cocotier) Virgilio lu~onensis Muir•• Philippines coconut
Achilidae Srnedoche helenae Van Duzee USA (California) Washingtonia filifera
Cixiidael /\1yndus crudus Van Duzee- southern USA, Caribbean (Caraibes) coconut and other palms (cocotier et Olilres palmiers) M_mdus taffini Bonfi!s+ ew Hebrides (Vanuatu) coconut
Derbidae1 Many species recorded Africa, Asia, S. USA adults on various palms (Nombreuses especes recensees) (Sud des USA) (adultes sur divers palmiers)
Ricaniidae Ricania speculum Walker Malaysia (Malaisie) ·' oil-palm (palmier ii huile) Pocha~ia fasciata (Fabricius) Africa oil-palm/coconut (p. ii huilelcocotier)
Membracidae ldioderma virescens Van Duzee•• USA, Dominican Rep. Seronoa repens, Phoenix roebelinii
Cicadidae Diceroprocta apache (Davis) USA : California date palm (palmier dallier) Proarna hilaris Germar Jamaica coco nm
Cicadellidae Recilia mica Kramer+ W. Africa (Afrique Guest) oil-palm/coconut Anocofana makilingensis (Baker)** Philippines coconut Sochinsogonia longa (Walker)** Philippines coconut (Cocotier) Bakera nigroscuta (Mahmood)** Philippines coconut
Indicates species breeding on palms (especes qui se reproduisenr sur /es palmiers). Known vector species (espece connue comme eta/II un agent vecteur) . Adult host records only (recensemem des adultes h6tes seulement) Ok~! ginetn . \"ol. ·B. n < 6 - Juin 1988 - 249
yellowing, also affect other palms. Table 11 gi\'CS a in Z. lo/Ju/111a populations. Transfer experiments reported summary of these diseases of coconut. their causes (where by Smith show that Z. lo/J11/a1a is intimately inrnlvcd in known), vectors and distribution. the Fimchhaffen coconut disorder. Feeding by large numbers caused symptoms \'ery similar to those observed on young palms. In the original description of Z. lobulata, I. - Cadang-cadang : Philippines. Ghauri [ 1966] records that up to 1,000 insects per frond had been found. Smith also reported that the remission of Cadang-cadang occurs on the Philippine islands of symptoms indicated that it was unlikely that a viroid or Luzon, Samar and neighbouring islands where it is des mycoplasm3-like organism was. in,·olved. The symptoms tructive to coconut palms O\'er 10 years old [Zelazny & could be taken for a form of hopperburn. Pacumbaba, 1982] . The disease is thought to be caused by A similar disorder of coconuts in the Solomon Islands. a \'iroid and viroid-l ike R!\:'1. has been transmitted mecha associated \\'ith the presence of another lophopid, Paine/la nically [Randles et al., 1977]. Many insects have been simmondsi \luir, was reported by Stapley [1 976, 1978]. tested unsuccessfully as \·ectors of this disease, including leafhoppers and planthoppers. These attempts have been re\'iewed by Bigornia [ l 9i7]. Zelazny and Pacumbaba 3. - Palm lethal yellowing. [1 982] surveyed the insects associated with both diseased and healthy palms with the aim of drawing up a li st of T his syndrome, was named lethal yellowing by Nutman species which should be gi\'en priority for fu ture insect & Roberts [1955] for the disease of coconut palms in transmission trials. Sixty-three insect species were caught Jamaica. Howard [1 983] reviewed the literature on the by means of sticky traps or by direct aspirating from disease both in the S . USA and Caribbean as well as on the leaves. Homoptera (leafhoppers, planthoppers, aphids a nd similar, if not identical, diseases in Africa. Here mention coccids) with 52 species formed the highest proportion (the will be m ade only of the lethal yellowing conditions that remainder being Orthoptera, Coleoptera and Heteroptera). have been impli cated with transmission by Auchenorrhyn Fourteen species of Homoptera were fou nd breeding on cha. coconut. T he results of the survey indicated that no single species could be considered as a suspect for transmitting a) Lethal yellowing : southern USA, Caribbean. Cadang-cadang. The literature is extensive and only selected papers a re mentioned here. Experimental work in Jamaica has been reviewed by Johson & Eden-Green [1978] while the search 2. - Finschhaffen disorder : Papua New Guinea. for a vector in Florida prior to 1980 was reviewed by Tsai [1 980]. The magnitude of the problem may be gauged The symptoms of this disorder include gradual yellow from the information that since 1971 when first reported bronzing from the tip of leanets towards the petiole. As from mainland Florida, lethal yellowing has killed 80-90 p. the condition advances the leaflet tips become necrotic and I 00 of the estimated I million of the susceptible Jamaica the necrosis spreads to those areas affected by bronzing. Tall variety coconuts [Howard, pers. comm.] As Tsai The lower fronds may die prematurely. This disorder was [1980] states « the aesthesic value and environmenta l first noticed in 1960 near Finschhaffen, Morobe province impact of the coconut palms in South Florida are far in Papua New Guinea. Smith [1980] summa ri ses the infor greater tha n the simple monetary value ». Lethal yellowing mation available on the disorder and its link with the has been the subject of a considerable research effort over feeding of the lophopid planthopper Z. lobulata Ghauri. It a long period in order to find the vector. Most insect was noted that a large build up of the insects preceded surveys concentrated on Homoptera on the assumption damage symptoms and any improvement in previously that the vector came from this group. No firm conclusions affected palms appeared to be related to a general decrease resulted from these surveys but incidental evidence for the
TABLE II. - Summary of diseases of coconut with which Auchenorrhyncha have been implicated or suspected of transmission. Details and references are given in the text (Resume des maladies du cocotier ou /es Auchenorrhynques sont imp!iques ou soup~onnes d'e1re impliques dans la transmission. Les details et !es rjjerences se trouvent dans /'article)
Country/Region Disease Vector(s) (Pays/region) (Maladie) Cause (Vecteur)
Philippines « Cadan-cadang » viroid (viroide) ?? (Auchen. tested - testes) New Hebrides (Vanuatu) « Lethal decay » MLO? virus? Myndus raffini (Cixiidae) (Deperissement mortel) Papua New Guinea « Finschhaffen disorder » 1-lopperburn ? Zophiuma lobulata (desordre) (Brulures de sauterelle) (Lophopidae) Solomon Islands Local hopperburn Paine/la simmondsi (Brulure de sauterelle locale) (Lophopidae) Southern USA (Sud des USA) Lethal yellowing MLO Myndus crudus (Cixiidae) Caribbean (Caraibes) (Jaunissemenl morlel) Africa : Tanzania Lethal decline MLO ?? Auchen. being tes ted (Deperissement mortel) (en cours de test) Africa : W. Africa Dry bud rot ?? Soga/el/a kolophon, (Afrique de /'Quest) (Pourrilu re seche du Ca'U r) Soga/odes cubanus (Delphacidae) Africa : W. Africa «Blast» ?? Recilia mica (Cicadellidae) 250- O!eagineux. Vol. ..+3, n ° 6 - Juin 1988
role of the cixiid ,\t_l'lld11s crudus \ "an Duzee has 4. - Dr~ bud rot : West Africa. accumula1ed O\-er several \·ears. Howard & !\lead [ 1980] found M. crudus on all but 1hc rarest lethal yellowing Dry bud rot affects voung coconuts and only rarely oil sus.::cp1ible palm specie,. Successful transmis sion palm, and \\a'> first id en1ified in 1972 [Renard er al., 1975]. experiments with lv!. crudus were reported in 1983 Julia [ 19 79] showed that the 'ector was a delphacid, [Howard et al.] but methods of control have still lo be subseq uemly identified as Sogare//a ko/ophon (Kirkaldy) im·est igated. The role of .\fy11d11s crudus in lethal yellowing and Sogarodes cubanus (Crawford) [Julia & Mariau, is fully reviewed in a paper by Holl'ard [ 1987]. 1982]. Both species breed on grasses and J ulia & Mariau [1982] stale tha1 the incidence of the disease at any site is b) Lethal disease : Tan~ania. due partly to the rnriable development of the hos1 grasses. Elimina1ion of grasses is a form of preve111ive control in .-\ lethal yellowing syndrome has apparently been coconut seed-beds and nurseries. The causative agent of known in coconut palms in Tanzania for at least 30 years the disease is not known. [Nienhaus er al., 1982] . In a survey carried out in Tanzania [Steiner, 1978] many palms showed symptoms of le thal yellowing but no pa1hogens including MLO could be 5. - Blast disease : West Africa. identified, but !\!LO association was demons1ra1ed by Nienhaus et al. [!982]. r\ full description of the disease Blasi disease, which is confined 10 Africa, is a disease of syndrome was gi\·en by Schuiling er al. [198 !]. The vector young coconuts and of oil-palm [Julia, 1979]. The grass has yet to be identified and tests are currently being carried feeding cicadellid Recilia mica Kramer was shown to be the ou1 with a range of Auchenorrhyncha [:-.!. Schuiling pers. vector of blast disease to oil-palm [Desmier de Chenon, C0/11111.]. 1979] and of blast to coconuts [Julia, 1979] .
c) Foliar decay : Vanuatu. The wilt disease now known as " Foliar decay of CONCLUSIONS coconuts by flt. raffini » (FDMT) has been known since 1965 on Santo Island, Vanuatu [Julia. 1982]. The disease From 1hose records given here it may be seen that only affects introduced coconuts and has never appeared various Auchenorrhyncha species are suspected, implicated on native varieties. The \·ector of the disease has been or have been shown to be vectors of several diseases of found to be a cixiid [Julia, 1982] and the species was palms in several areas of the world. Interestingly these named M. taffini Bonfils [ 1982]. Recent results [Julia et vectors ha,·e come, not from species that breed on palms, al., 1985] have shown by indirect evidence that the causal but from those that feed more or less regularly on palms agent is unlikely to be an l\1LO. Single- stranded DNA has and actually breed elsewhere. The implication for survey been extracted from diseased leaf tissue [Randles et al., work has already been grasped since the search for a vector 1986] and may indicate a virus as the causal agent. is usually wide ranging.
REFERENCES
JI] BIGORNIA A. E. (1977). - Evaluation and trends of researches (II] JOHNSON C. G. & EDEN-GREE/\ S. J. (1978). - The search on the coconut Cadand-cadang disease. Philipp J. Coconut Stu for a ,·ector of Lethal yellowing infected coconut palms : A reap dies, 2, p. 5-34. praisal of experiments from 1%2-1971. FAQ Plant Protection [21 BONFtLS J. (1982). - Description d'une espece nouvelle de Cixiidae Bull., 26. p. 13 7-149. nui<;ible aux plantations de cocot iers (Hom. Fulgoromorpha). Bull. (12] JOSEPH T .. SHANTA P. & LAL S. B. (1972). - Role of Soc. ent. Fr., 87, p. 381-384. Stephanitis typicus. Dis1a nt in the spread of coconut root (wilt) (31 DES~11ER de CHENON R. (t979). - ~ti
121 ] \LT\IAN I· . .I. & KO!ll:RT'> P. \I. (19551 - Le1hal 'ellow111". [."'!.-:'] S~ ll 111 I ~ ( (19M!l - /.011h111111i1 lohula1a l1haun (flunwptl..'ra 1he (( unk1u1,\ n dii.;.c;v.c 1· L'f l.'.'o ...·onul palm' Ill Jamaica.· Empire ... ./. I prtw;1iJ:1cl and 11-. rda11cm io the I 1mch haffc 11 conrnu1 di,ordt:r £.\p. , 1gnc .. 23. r. 25-.:6-. in 1';1:'u:1 '-e'' C. uinc.1 / 1a1wa .\ CH" Ciwnea ,.. l l!ric. ./.. 31. p .r-~5 122] PERTHU IS B.. DES\llER co CHE'
RESC'.\tE RESUME:\ Recensement des Homopteres Auchenorrhyncha trouves Censo de homopteros Auchenorrh_rncha encontrados en sur les palmiers et leur association avec des maladies las palmas. y asociacion de estos con las enfermcdades du cocotier. del cocotcro. M. R. WILSON. Oleagineux, 1988, 43, N° 6. p. 247-253 . i\I. R. WILSO'.'J. O/eagineux, 1988, 43, N° 6, p. 247-253. Les insectes arpartenam au:- Homopteres Auchenorrhynques Se realize el censo de inscctos de! suborden de hom6p1eros associes avec les palmiers ont ete recenses. Neuf families de Fulgo Auchenorinco' asociados con las palmas, encontrandose en las roidaea ont etc trouvecs sur lei palmiers e1 cinq parmi celles-ci : palmas nue,·e familias de Fulgoroidaea. cinco de las cuales, o sea Delphacidae, Tropiduchidae, lssidae, Lophopidae et Fla1idae son1 Delphacidae. Tropiduchidae, Issidae. Lophopidae y Flatidae, se represen1ees par des especes qui se reproduise n1 su r !es palmiers. II hallan representadas por especies que se reproducen en las pal est egalement admis que plusieurs especes de Cicadellidae et une mas. Asimismo se admite que varias especics de Cicadellidae y espece de Membracidae se reproduisem sur !es palmiers. De nom una especie de :'\1embracidae se reproducen en las palmas. Muchos breux Cixiidae ct Derbidae. dom !es nymphes sont trouvees dans Cixiidac y Derbidae, cuyas ninfas se encuentran en el suelo o en la le sol ou dans le bois pourri , se nourrissem sur palmiers au s1ade madera podrida. se alimentan en palmas en el es1ado adulio. El adulte. Le Tropiduchidae 0111111 ariss11s bi1101a111s lybicus de Berge Tropiduchidae 0111111a1iss11s binorn111s fybicus de Bergevin produce vin provoque des degats directs en se nourrissant su r dattier ainsi dai\os directos alimentandose en palmeras da1ileras, y dai\os indi que des degii1s indirects a cause du dc\'eloppement de champi rectos debido al desarrollo de hongos en el mielato que produce ; gnons sur le miellat qu'il produit ; le Lophopidae Zophiurna fobu el Lophopidae Zophiuma fob11fa1a Ghauri produce dai\os en el fa1a Ghauri pro,·oque des degiits su r le cocotier. Actuellement, !es coco1ero. Los Auchenorincos se es1an estudiando con el fin de Auchenorrhynques font l'objet d'etudes des1inees a examiner Ieur examinar su papel como vectores de ,·arias enfermedades de las role en tant que vec1eurs de plusieurs maladies des palmiers, y palmas, inclu so el amarillamien10 le1al. Se da un resumen de las compris le Jaunissement mortel. Un resume des maladies affec enfermedades que afectan el coco1ero. Se lleg6 a encomrar espe tant le cocotier es1 donne. Des especes vectrices ont ete trouvees cies vectoras entre las que no realizan su ciclo de desarrollo en parmi cel!es qui n'ont pas la caracteristique de realiser leur cycle palmas pero consumen a menudo hojas. siendo la mas conocida el de developpement sur !es palmiers mais qui se nourrissent fre Cixiidae Afrndus crudus Van Du zee, wctor de! amarillamiento quemment des feuilles ; la plus connue est le Cixiidae Myndus morlal de las palmas en el Sur de Es1ados Unidos y en la zona de! crudus Van Duzee, vecteur du Jaunissement mortel des palmiers Cari be. dans le Sud des Etats-Unis et dans !es Cara"ibes. • Recensement des Homopteres Auchenorrhyncha trouves sur les palmiers et leur association avec des maladies du cocotier
M. R. WILSON (1)
INTRODUCTION dae) qui allaquent le cocoiier, respecti,·ement, en Afrique et dans !es iles du Pacifique [voir Lever, 1969]. Parmi !es Auchenorrhyn Les palmiers sont attaques par un grand nombre d'insectes et ques, seu l 0111111a1issus bi1101a1us var. lybicus Bergevin (Tropidu Lepesme (1947] a releve et etabli une liste de tous ceux, nuisibles chidae) est comm comme e1ant un ra,·ageur important des dattiers ou non, que l'on rencontre sur !es palmiers. En general, Jes du Moyen-Orienl. Lever [ 1969] ne mentionne aucune espece Hemipteres ne sont pas consideres comme 1res nuisibles aux pal d'Auchenorrhynques dans sa lisle d'insectes nuisibles au cocotier. miers, avec des exceptions comme Pseudo1heraptus wayi Brown Mais, de plus en plus frequemment, Ies Hemipteres sont impli (Heteroplera Coreidae) et Amblypefta spp. (Heteroptera : Corei- ques dans Ia 1ransmission des agents pathogenes de certaines maladies des palmiers, tel le Jaunissement mortel. En ce qui con cerne !es Heteropteres, on sait aujourd'hui que certaines especes (I) CAB ln1erna1ional lnstilUle of En1omology, 56 Queen's Gale, Lan de punaises pentatomides transmettent des maladies a flagellees dres, SW7 5JR (Grande-Brelagne). (Phytomonas) aux palmiers d'Amerique du Sud [Desmier de Che- 252 Oleagincux. \'ol. 43, 11 ° 6 - Juin 1988
non. 198.J] ; le« Hanrot » du .:ocotier [Louise el al., 1986] ct la des C '.P~'~ ' qui dnra1cnt ctrc te; tee, en pnorite dans le ,., es,.,ai> « :-.larchitez sorpresiva » du palmier a huile [Dolling, 1984 ; Per ultericur' de transmission en cage. Soi\ante-trois especes d'insec thuis el al. , 1985] sont tran;mi ; par Lincus spp. En Inde, le vec tes o m etc cap111rces dam des pieges it glu ou par aspiration teur d'un deperissement des ra.:ines (Root Wilt disease) affcctant direct c b) Les maladies mortelles : Ta11~a11ie. en 1972 [Renard el al .. 1975]. Julia [1979] a 111on1 rc que !"agent Un syndrome du jaunissement mortel est apparemment connu vecteur etait un Dclphacidae. idcntifie par la suite comme ctant sur Jes cocotiers en Tanzanie depuis au moins 30 ans [Nienhaus et Soga1e//a kolof!lwn ( l-.1rl-ald) I et Soga1odc1· c11/Ja1111~ (Cra" ford) al., 1982]. Au cours d'une prospection realisee en Tanzanie [Stei [Julia et Mariau. 1982]. Ces deux especes sc reproduisent sur !es ner, 1978], de nombreux palmiers manifestaient des sympt6mes graminees et Julia et l\lariau [1982] ont constate que !"incidence du jaunissement mortcl. Neanmoins, aucun agent pathogene n 'a de la maladic dans n 'importe quel site etait due. en partie. a !'importance du dcveloppemcnl des graminees. L'elimination des pu alors etre identifie, ni meme des organismes de type myco plasme (MLO). bien que !'associa tion de la maladie al"ec des graminees est une forme de con1r6le preventif dans !es champs semenciers et Jes pcpinieres de cocotier. L'age111 causal de la rnala- MLO ait ete mise en evidence par Nienhaus e1 al. [ 1982]. Une des cription detaillee du sy ndrome a ete faite par Schuiling et al. die reste inconnu. - [1981]. L'agent l"ecteur reste a identifier et Jes essais sent actuelle ment en cours awe divers Auchenorrhynques [M. Schuiling, com e) Le Blast : Afrique de /"Ouesr. munication personnelle]. Le Blast, qui ne se trouve qu'en Afrique, affecte le cocotier et le palmier a huile au jeune age [Julia . 1979]. On a montre qu'un c) Le Deperissement foliaire : Vanuatu. Cicadellidae, Recilia mica Kramer, qui se nourrit sur graminees. est !'agent vcctcur du Blast, aussi bien pour le palmier a huile Le deperissement connu actuellement sous le nom du Deperisse [Desmier de Chcnon, 1979] que pour le cocotier [Julia, 1979] . ment foliaire transmis par M. taffini (DF\!T) est connu depuis 1965 sur l'ile de Santo, Vanuat u [Julia, 1982]. La maladie n'affecte que !es introductions et n'a jamais ete observee sur !es CONCLUSIO'.'I varietes locales . On a decouven que !'agent vecteur est un Cixii dae [Julia, 1982] et l'espece a ete nommee M. raffini Bonfils [1982]. Des resultats recents [Julia er al., 1985] montrent pa r preu Les informatio ns rapportees ici montrent que le role de diverses ves indirectes que !'agent vecteur n'est probablement pas un especes d ' Auchenorrhynques comme agent vecteur de plusieurs MLO. Des AON simple brin ont ete extraits de ti ssus foliaiies maladies des palmiers dans diverses regions du monde est, selon le malades [Randles er al., 1986] ce qui laisserait penser que !'agent cas, confirme ou soupc;onne. II est interessant de noter que ces causal est un virus. agents vecteurs ne sont pas des especes qui se reproduisent sur Jes palrniers mais des especes qui se nourrissent plus ou mains regulie rement sur palmiers et se reproduisent ailleurs. Les implications d) La Pourrirure seche du creur : Afrique de l 'Ouest. pour !es travaux de prospection sont deja evaluees puisque la La Pourriture seche du cceur qui affecte !es jeunes cocotiers, et recherche d ' un a gent vecteur necessite generalement un travail tres rarement le palmier a huile, a ete identifiee pour la premiere fois etendu . .------INDEX DES ANNONCEURS----~ AMERICAN EXPRESS couv. p . 4 GIANAZZA ...... II BANQUE NATIONALE DE PARIS ...... couv. p. 3 HERSTAL (Ateliers de Construction de) p. 240 BLOHORN p. 254 OLIER (Ste Nouvelle des Ets) v BRUKER .. couv. p. 2 RENTEC ...... VI CAP-KEK . . ... VI CIBA-GEIGY ...... p. 246 SAMAT (Les Fils de Louis) IV FAUGERE et JUTHEAU ...... IV WECKER (Usine de) ...... Ill