Orseolia oryzivora (African rice gall midge)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Seedborne Aspects
- Plant Trade
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Orseolia oryzivora Harris & Gagné, 1982
Preferred Common Name
- African rice gall midge
Local Common Names
- West Africa: cécidomyie du riz
- ORSEOV (Orseolia oryzivora)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Diptera
- Family: Cecidomyiidae
- Genus: Orseolia
- Species: Orseolia oryzivora
Notes on Taxonomy and NomenclatureTop of page
DescriptionTop of page
Eggs are elongate cylindrical, about 0.5 mm long, initially white but orange-yellow just before hatching.
All larval stages lack jointed legs or other obvious appendages and are relatively featureless with small heads which partially retract into the anterior segments of the thorax. As far as is known, there are three larval instars. Body colour varies from white to pink. Full-grown final instar larvae are up to 5 mm long and have a median ventral sternal spatula on the first thoracic segment.
Pupae are 5-7 mm long and female pupae are generally larger than males. The antennal horns taper to a single point and the abdominal tergites bear series of spines. See Harris and Gagné (1982) for further details, including SEMs of diagnostic characters.
Adults are small reddish-brown midges with a wing length of about 3.0-3.5 mm in males and about 3.5-4.0 mm in females. Both sexes have long antennae composed of 12 flagellomeres which, in males, have three sets of linked filiform sensoria (circumfila). The male terminalia form a bilaterally symmetrical clasper and the female ovipositor is non-retractile with a pair of distal cerci. Diagnostic characters are described and illustrated in Harris and Gagné (1982).
DistributionTop of page
O. orzivora has also been reported in Guinea, Sierra Leone and Tanzania (K Harris, c/o CABI Biosciences Division, Silwood Park, Ascot, UK, unpublished data).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 10 Jan 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Guinea||Present||Original citation: Harris personal communication, 1984|
|Tanzania||Present||Original citation: Harris personal communication, 1984|
Risk of IntroductionTop of page
HabitatTop of page
Hosts/Species AffectedTop of page
Host Plants and Other Plants AffectedTop of page
Growth StagesTop of page
SymptomsTop of page
List of Symptoms/SignsTop of page
|Growing point / internal feeding; boring|
|Inflorescence / galls|
|Leaves / abnormal forms|
|Stems / witches broom|
Biology and EcologyTop of page
Female rice gall midges lay eggs on the inner or outer surfaces of a leaf sheath, just below the ligules, or on the upper or undersides of leaf blades of young rice plants, either singly or in groups of 3-5 eggs. Each mated female lays up to 400 eggs during a 3-day life span. Eggs hatch about 3 days after laying and first instar larvae move to the growing points where they feed for 2-3 weeks. Larval feeding induces development of the gall which is short and inconspicuous until larvae are ready to pupate. The gall then elongates and the pupa works its way up the gall and abrades an emergence hole through which it protrudes when the adult emerges. Each gall contains a single larva and galls generally appear about 20-40 days after the crop has been transplanted.
Observations on this species reared in cages in Burkina Faso (Bouchard et al., 1992) indicated that development from egg to adult took 23-36 days at 27°C and that adult emergence continued for 10 days, with maximum emergence at 3-6 days. Males and females emerged at about the same time and the sex ratio of reared male to female adults was 1:2.
In south east Nigeria, Umeh and Joshi (1993) recorded that adults appeared in light traps during the third week of June in 1991 and peak emergence occurred 8 weeks later.
In Malawi, Feijen and Schulten (1983) recorded that the life cycle from egg to adult was not more than a month and that under favourable conditions it might be much shorter. They also suggested that up to nine successive adult generations developed during the 1973-1974 rainy season.
Natural enemiesTop of page
Notes on Natural EnemiesTop of page
In Burkina Faso, Dakouo et al. (1988) observed both parasitoid species and noted that they provided an important check to pest populations with up to 77% of larvae parasitized late in the season.
In south east Nigeria, Umeh and Joshi (1993) monitored seasonal development of these two species during the 1991 growing season and recorded that P. diplosisae appeared first, followed 3 weeks later by A. procerae. Subsequently, parasitism by the two parasitoids increased steadily and reached 98% by the 28th week. Galls parasitized by P. diplosisae were shorter and thicker than unparasitized galls but no differences were apparent in galls parasitized by A. procerae, which generally attacked pupae by ovipositing through the gall.
The widespread occurrence of both parasitoids in West Africa and their effects on midge populations have since been confirmed by Williams (c/o CABI Biosciences Division, Silwood Park, Ascot, UK, unpublished data).
Seedborne AspectsTop of page
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Seedlings/Micropropagated plants||eggs; larvae; pupae||Yes||Pest or symptoms usually visible to the naked eye|
|Plant parts not known to carry the pest in trade/transport|
|Fruits (inc. pods)|
|Growing medium accompanying plants|
|Stems (above ground)/Shoots/Trunks/Branches|
|True seeds (inc. grain)|
ImpactTop of page
In 1988 the situation changed dramatically when a major outbreak caused serious losses in the savanna zone of Nigeria, with 45 to 80% of all tillers infested in the most severely affected areas and consequent serious reduction of yields in some fields (Ukwungwu et al., 1989). By 1997 severe outbreaks, with tiller infestation of 20% or more, occurred regularly in several important rice growing areas of Nigeria, Burkina Faso and Mali and the midge was considered a key pest of lowland rice in those countries. Its pest status elsewhere in Africa was much less certain but conspicuous localized outbreaks had been reported from Mali, western Sierra Leone, Guinea, Guinea Bissau, northern Ghana, southern Chad and at rice irrigation schemes in Tanzania and Uganda (C Williams, c/o CABI Biosciences Division, Silwood Park, Ascot, UK, unpublished data).
In Burkina Faso, cage experiments on yield losses resulting from artificial infestations indicated that, although infestation induced some compensatory production of tillers, there was a significant negative correlation between yield and infestation with a 2% grain yield loss for each 1% tillers damaged (Nacro et al., 1996).
In eastern Nigeria, trials at 47 rain-fed lowland farm sites in 1995 provided detailed and consistent yield loss data for natural infestations. Regression analysis indicated incremental yield losses of 2.3 to 3.1% for each increase of 1% tillers with galls at 7 to 9 weeks after transplanting, over the range 0-30% infestation. Similar research station trials on irrigated rice, using artificial infestation, indicated lower levels of yield loss, probably because midge attack was less prolonged and agronomic conditions were more favourable than on farmers' fields (C Williams, c/o CABI Biosciences Division, Silwood Park, Ascot, UK, unpublished data).
DiagnosisTop of page
The genus Orseolia can be separated from other genera of Cecidomyiidae likely to be found in association with cultivated plants, as follows:
Female ovipositor non-retractile and with relatively large terminal cerci; male terminalia with undivided hypoproct, densely clothed in microtrichia; antennal formula 2+12 in both sexes; males flagellomeres trifiliar, with long necks and internodes and relatively short circumfiliar loops; female flagellomeres elongate cylindrical, with long necks and simple, linked circumfiliar.
Detection and InspectionTop of page
Light-trapping is used to detect adult activity of the Asian rice gall midge and has been used by Umeh and Joshi (1993) to monitor seasonal fluctuations in adult activity in south east Nigeria.
Similarities to Other Species/ConditionsTop of page
Similar symptoms are caused by lepidopterous stem borers and by some diseases but these do not involve the production of galls.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
The published literature on control methods is limited as little conclusive research has been completed since this species first became a major pest.
Integrated Pest Management
Plant breeding for resistance or tolerance to midge attack shows greatest promise at present. One Oryza sativa improved variety, 'Cisadane' has reasonably high yield potential and has shown tolerance to natural midge infestations in on-farm trials in Nigeria. In addition, an intensive screening programme in Nigeria has identified sources of resistance to heavy midge infestations in the indigenous African rice, Oryza glaberrima, and in several traditional African varieties of the exotic Oryza sativa. Screening, selection and breeding is co-ordinated by the West Africa Rice Development Association (WARDA) in conjunction with national programmes, especially at the National Cereals Research Institute (NCRI), Nigeria and the Institut National d'Études et de Recherches Agricola (INERA), Bobo-Dioulasso, Burkina Faso.
Other elements of integrated pest management are under investigation with the aim of providing a selection of mutually compatible management options from which farmers and local support services can select appropriate cost-effective measures for their particular circumstances. The main objectives are:
To find methods to reduce the abundance of alternative hosts outside the cropping season and so limit midge colonization of early planted rice crops.
To reduce the period during which rice crops are susceptible to midge infestation by synchronizing wet season planting of rice, so far as agronomic and socio-economic restraints permit.
To retard the rate of midge population increase within rice crops by the use of varietal resistance/tolerance, the enhancement of natural biological control or the use of appropriate chemical control.
A preliminary assessment of the potential for classical biological control has been made but no obvious candidate agents have been identified (Harris, Cock and Williams, c/o CABI Biosciences Division, Silwood Park, Ascot, UK, unpublished data). It may however be possible to enhance natural indigenous biological control by conservation and management of Aprostocetus procerae and Platygaster diplosisae (C Williams, c/o CABI Biosciences Division, Silwood Park, Ascot, UK, unpublished data).
Trials in Nigeria reported that isazofos was as effective as diazinon in controlling midge infestation (Ukwungwu, 1990).
An alternative to field application of insecticides is treatment of young plants by immersion in insecticide to kill eggs and young larvae before transplanting (Betbeder-Matibet, 1990).
The potential danger of widespread and inappropriate use of insecticides against this pest is an important incentive for the speedy development of non-insecticidal methods of control.
ReferencesTop of page
Betbeder-Matibet M, 1990. Insect pests of food crops in Africa and the Indian Ocean region. Montpellier, France; Centre de Cooperation Internationale en Recherche Agronomique pour le Developpement, Institut de Recherches Agronomiques Tropicales, 122 pp.
Dakouo D, Nacro S, Sie M, 1988. Seasonal incidence of the rice gall midge, Orseolia oryzivora H. and G. (Diptera, Cecidomyiidae) in the south-west of Burkina Faso. Insect Science and its Application, 9(4):469-473
Descamps M, 1956. Deux dipteres nuisibles au riz dans le Nord Cameroun Pachydiplosis oryzae Wood Mason Pachylophus sp. aff. lugens Loew. Phytiatrie-Phytopharmicie, 5:109-116.
Feijen HR, Schulten GGM, 1983. Note on the African rice gall midge Orseolia oryzivora Harris & Gagne (Diptera, Cecidomyiidae), with a redescription of its parasitoid Tetrastichus pachydiplosisp Risbec (Hymenoptera, Eulophidae). Zeitschrift für Angewandte Entomologie, 96(5):509-520
Harris KM, Gagne RJ, 1982. Description of the African rice gall midge, Orseolia oryzivora sp. n., with comparative notes on the Asian rice gall midge, O. oryzae (Wood-Mason) (Diptera: Cecidomyiidae). Bulletin of Entomological Research, 72(3):467-472
Nacro S, Heinrichs EA, Dakouo D, 1996. Estimation of rice yield losses due to the African rice gall midge, Orseolia oryzivora Harris and Gagne. International Journal of Pest Management, 42(4):331-334; 14 ref.
Taylor DR, Fomba SN, Fannah SJ, Bernard HM, 1995. African rice gall midge pest in Sierra Leone. International Rice Research Newsletter, 20, 27
Umeh EDN, Joshi RC, 1993. Aspects of the biology, ecology and natural biological control of the African rice gall midge, Orseolia oryzivora Harris and Gagne (Dipt., Cecidomyiidae) in south east Nigeria. Journal of Applied Entomology, 116(4):391-398
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Harris K M, Gagne R J, 1982. Description of the African rice gall midge, Orseolia oryzivora sp. n., with comparative notes on the Asian rice gall midge, O. oryzae (Wood-Mason) (Diptera: Cecidomyiidae). Bulletin of Entomological Research. 72 (3), 467-472. DOI:10.1017/S000748530001364X
Taylor DR, Fomba SN, Fannah SJ, Bernard HM, 1995. African rice gall midge pest in Sierra Leone. In: International Rice Research Newsletter, 20 27.
Distribution MapsTop of page
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