Rice Gall Midge Orseolia Oryzivora Research Articles

Parasitism and development of Platygaster diplosisae (Hymenoptera: Platygastridae) on the African rice gall midge Orseolia oryzivora (Diptera: Cecidomyiidae)

The life cycle of the koinobiont endoparasitoid Platygaster diplosisae Risbec was investigated to assess its suitability as a biological control agent of the African rice gall midge Orseolia oryzivora Harris & Gagne. Screen house and laboratory experiments were conducted in 2008 under ambient conditions in Ibadan, Nigeria. Morphological characteristics of the parasitoid’s immature stages were observed, and its life cycle parameters were measured. The parasitoid’s average egg incubation period was 12.9 days, and on average, 67.3% of eggs hatched. Three instars occurred, with average developmental durations of 2.2, 0.5 and 2.5 days for the 1st, 2nd and 3rd instars, respectively. Pupal development took 6.7 days until adult emergence. Pre-oviposition period averaged 12.1 h, and a female laid on average 95.2 eggs, with a mean oviposition period of 3.5 days. The longevity of males and females was 3.0 and 4.1 days, respectively, without food; longevity was extended when honey and water were provided. Mating and oviposition behaviours were recorded, and a sex ratio of eight females to one male was found in parasitoid progeny. The parasitoid had a total developmental period of 27.3 days, which is about 5 days longer than that of its host. In conclusion, P. diplosisae can play an important role in the biological control of O. oryzivora on rice, and should be conserved in African rice production systems.

Biology of the African rice gall midge Orseolia oryzivora (Diptera: Cecidomyiidae) and its incidence on wet-season rice in Nigeria

The biology of the African rice gall midge Orseolia oryzivora Harris and Gagne was investigated in screenhouse and laboratory studies, and its incidence on cultivated wet-season rice was studied in farmers’ fields during the 2006 and 2007 rice-growing seasons at two localities in Nigeria. This insect is nocturnal, and mating takes place immediately after emergence. Both mated and unmated females lay eggs, with mated females laying on average 389 eggs each, and unmated females laying about 87 sterile eggs. The egg stage takes on average 2.5 days. Larval development takes 3.6, 3.3 and 3.0 days for the first, second and third instars, respectively, while the pre-pupal and pupal stages take 2.8 and 6.1 days, respectively. Adult females live for 48–78 h, while males live for 24–30 h. The life cycle of O. oryzivora is completed within 21–24 days under screenhouse conditions. The adult male is slender and about 3 mm long, while the female is more rounded with a 4 mm long body and a bright red abdomen. The insect produces unisexual progeny. Field incidence is low at the beginning of the rainy season, peaking with the peak in rainfall and humidity that concurs with the vegetative stage of the crop. The population of the midge declines as temperatures rise. In conclusion, prediction models may be developed based on weather parameters, to aid in forecasting the field incidence of O. oryzivora and its management strategies. Furthermore, it maybe possible to reduce the damage caused by O. oryzivora to rice crops by altering planting period and taking into account environmental factors.

Screening of African rice, oryza glaberrima steud, for resistance to the African rice gall midge orseolia oryzivora Harris and Gagne

Two hundred seventy-three lines of the cultivated African rice species Oryza glaberrima Steud were screened in a paddy screenhouse at the National Cereals Research Institute, near Bida, Niger State, Nigeria for resistance to the African rice gall midge, Orseolia oryzivora Harris and Gagne, an increasingly important pest of lowland rice in Nigeria. Twenty entries which showed no galls in the screenhouse evaluation were retested under natural infestation in a gall midge-endemic field location near Abakaliki, Ebonyi State. Whereas the susceptible check variety, FARO 37, had 39.6 % of tillers infested 60 days after transplanting, damage in the test entries ranged from 0 to 3.7 %, an indication that they were all highly to moderately resistant to the pest. Greater host plant resistance is a central requirement for more effective management of O. oryzivora. Using resistance genes from O. glaberrima is a promising approach to achieving this.

Population dynamics of the African rice gall midge Orseolia oryzivora (Diptera: Cecidomyiidae) and its parasitoids in the forest and southern Guinea savanna zones of Nigeria

The African rice gall midge (AfRGM) Orseolia oryzivora Harris and Gagne is an important insect pest of rice in Nigeria. Studies were conducted at Ogidiga (forest zone) and Edozhigi (southern Guinea savanna) in Nigeria, under rainfed lowland conditions during the 2006 and 2007 rainy seasons, on the population dynamics of AfRGM adults using light trap and random sampling of % tiller infestation (plant damage due to AfRGM) and % parasitism by Platygaster diplosisae Risbec and Aprostocetus procerae Risbec (parasitized larvae and pupae and parasitoid species present in dissected tillers). The results obtained showed that AfRGM populations were relatively low in June and July - the beginning of the 2006 and 2007 rainy seasons, respectively - and increased abruptly from September, reaching a peak in October at both locations. The increase was attributed to the rapid build-up of the pest populations at both locations. There were strong positive correlations between adult populations from light-trap catches and % tiller infestation, and between % tiller infestation and parasitism. The peak period of parasitism by P. diplosisae and A. procerae occurred towards the end of the rainy season in October, coinciding with high level of % tiller infestation. It is concluded that conservation of the parasitoids early in the cropping season (i.e. to improve their synchronization with the host) could become an effective management strategy against AfRGM.

Antixenosis component of rice resistance to African rice gall midge Orseolia oryzivora

Antixenosis component of rice resistance to African rice gall midge Orseolia oryzivora

Antixenosis component of rice resistance to African rice gall midge Orseolia oryzivora

Antixenosis component of rice resistance to African rice gall midge Orseolia oryzivora

The effect of planting date on the African rice gall midge Orseolia oryzivora (Diptera: Cecidomyiidae) damage under irrigated conditions in Boulbi, central Burkina Faso

Experiments were conducted during the rainy seasons in 2003 and 2004 in central Burkina Faso to assess the importance of the African rice gall midge Orseolia oryzivora Harris & Gagne in relation to the planting date under irrigated conditions. The young midge larva feeds at the growing point of the rice tiller, which stimulates the plant to produce an oval hollow gall that prevents the plant from heading. Experiments consisted of three treatments arranged randomly within each of the four replications. Treatments were planting dates separated by 7 days. The rice cultivar planted in the experiment was FKR 14, which matures in 120 days. Nine entomological evaluations (assessment of the number of galls per hill) were performed for each planting date, starting at 25 days after transplanting (DAT) and ending at 81 DAT. Evaluations were conducted on 20 randomly selected hills and consisted of counting the total number of tillers and galls per hill. These hills were identified on one of the two diagonals of each treatment. At the rice maturation stage, 20 randomly selected hills were harvested and the grains from each hill were weighed and recorded. Yield loss was estimated for each treatment from these data. Results showed that the later the planting date, the higher the damage caused by O. oryzivora. The damage was low (>10%) during the vegetative phase but increased dramatically (<20%) during the reproductive phase of the rice plant, regardless of the planting date. Yield losses were correlated to the observed damage: In 2003, for the first planting date, 1% of galling was associated with 1% yield loss, while the same level of damage was associated with 1.3% yield loss for the second planting date.

Morphological diversity and genomic DNA fingerprinting of the African rice gall midge Orseolia oryzivora (Diptera: Cecidomyiidae) and of two other species of African Orseolia

A morphological diversity study was conducted on African rice gall midge Orseolia oryzivora Harris & Gagne and two other African species, Orseolia bonzii Harris and Orseolia nwanzei Harris & Nwilene, sp. n. Morphological differences between adult and immature stages of the three species are slight and mainly evident in pupal characters. Due to limited differences in morphological characters, genomic DNA fingerprinting of these three insect species was carried out using random amplified polymorphic DNA (RAPD) and sequence-characterized amplified region (SCAR) methods. Out of 90 operon primers, 15 showed polymorphism among the three species tested, generating 86 bands, 60 (70%) of which were polymorphic. Primer OPV6 produced three RAPD markers that distinguished the three Orseolia species. These markers were cloned and sequenced. Their sequence was then used to design six SCAR primer pairs. Each SCAR primer pair amplified and distinguished the three Orseolia species at genomic DNA level. Both SCAR and RAPD genomic DNA fingerprinting revealed that O. oryzivora and O. bonzii are most closely related and O. nwanzei is distinct. Each of the six SCAR primer pairs produced a specific DNA fragment size specific for O. nwanzei, O. oryzivora and O. bonzii. The DNA fingerprints will be useful for entomological survey, identification of new species and differentiating aggressive from non-aggressive species, aimed at the effective development of rice cultivars with durable resistance to African rice gall midge.

Variation saisonnière des populations pré-imaginales de la cécidomyie africaine du riz Orseolia oryzivora et de ses dégâts en fonction des plantes hôtes dans le sud-ouest du Burkina Faso

The African rice gall midge Orseolia oryzivora is a major pest of rice in Burkina Faso. The present study was carried out during four consecutive crop seasons from 1999 to 2001, in three rice-irrigated schemes, near Bobo Dioulasso town in south Burkina Faso. The fluctuation of immature stages of the pest and their damage, with regard to host plants was monitored. These included the cultivated rice Oryza sativa and its ratoons, and wild rice Oryza longistaminata. Sampling on growing rice was carried out monthly in 1 m 2 quadrats, in each of 100 randomly selected farmers fields. Sampling on rice ratoons was carried out after rice harvest and 500 tillers were randomly selected in the same fields and taken to the laboratory for dissection. Data on wild rice were collected every month by sampling and dissecting 500 tillers per site. This study revealed that in the absence of rice, the pest survived on rice ratoons and wild rice. However, cultivated rice was the preferred host plant as the crop recorded over 15% galling during wet seasons while damage was very low in dry seasons. Results from this study represent an important step towards the development of an IPM programme to control the rice gall midge, with regard to its host plant relationships.

Multilocational screening of Oryza sativa and O. glaberrima for resistance to African rice gall midge Orseolia oryzivora in west Africa

Multilocational screening of Oryza sativa and O. glaberrima for resistance to African rice gall midge Orseolia oryzivora in west Africa

Screening of African rice, Oryza glaberrima Steud, for resistance to the African rice gall midge Orseolia oryzivora Harris and Gagné

Two hundred seventy-three lines of the cultivated African rice species Oryza glaberrima Steud were screened in a paddy screenhouse at the National Cereals Research Institute, near Bida, Niger State, Nigeria for resistance to the African rice gall midge, Orseolia oryzivora Harris and Gagne, an increasingly important pest of lowland rice in Nigeria. Twenty entries which showed no galls in the screenhouse evaluation were retested under natural infestation in a gall midge-endemic field location near Abakaliki, Ebonyi State. Whereas the susceptible check variety, FARO 37, had 39.6 % of tillers infested 60 days after transplanting, damage in the test entries ranged from 0 to 3.7 %, an indication that they were all highly to moderately resistant to the pest. Greater host plant resistance is a central requirement for more effective management of O. oryzivora. Using resistance genes from O. glaberrima is a promising approach to achieving this.

Efficacy of granular isazofos against rice gall midge in Nigeria

In a comparative test for the control of the rice gall midge Orseolia oryzivora Harris and Gagné, isazofos performed as well as carbofuran. Isazofos was equally effective at 0.75 kg a.i. ha −1 and 1.00 kg a.i. ha −1 against the gall midge but not at a lower dosage rate of 0.50 kg a.i. ha −1. Grain yield obtained at the three dosage rates was similar. Application of the insecticide once, twice or three times gave similar control of gall midge. Grain yield did not differ at the various treatment dates.