Scientific name: Orseolia (= Pachydiplosis) oryzae (Wood-Mason)
Common name: Asian rice gall midge
 Reddish mosquito-like female adult of Asian rice gall midge Orseolia oryzae (Wood-Mason)
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Taxonomy:
| Class | Insecta |
| Order | Diptera |
| Family | Cecidomyiidae |
Economic importance
In Lao PDR, Sri Lanka, and parts of India, this pest is an important yield constraint. It was reported to cause significant yield losses of 30-40% in several countries.
Geographical distribution
Bangladesh, Bhutan, Cambodia, China (southern), India, Indonesia, Lao PDR, Myanmar, Nepal, New Guinea, Pakistan, Sri Lanka, Thailand (northern), and Vietnam.
Morphology
Egg
Eggs are elongate-tubular. Newly laid eggs vary
from white to pink, red, or yellow. Before hatching, the eggs turn shining
amber. A single egg measures 0.5 mm long and 0.12 mm wide.
Larva
The larva is maggot-like and about 1 mm long.
The neonate larva is gray-white.
Pupa
The pupa is light pink. It is 2-2.5 mm long and
0.6-0.8 mm wide. Before adult emergence, it turns red. The pupa has abdominal
spines.
Adult
The adult is mosquito-like. The female midge has
a bright red abdomen, whereas the male has a yellow-brown body. The male is
generally smaller than the female. It has a wing expanse of 3.0-3.5 mm. The
female has a wing expanse of 3.5-4.0 mm. Both adults have bead-like antennae
with more than 10 segments. Their maxillary palpi are 4-segmented.
Symptoms
As a result of feeding, a hollow cavity or tubular gall is formed at the base of a tiller. The affected tiller fails to produce panicles. It also causes elongation of leaf sheaths called onion leaf or silvershoot.
The gall is a silvery white hollow tube, 1 cm wide and 10-30 cm long.
Biology and ecology
The Asian rice gall midge is found in irrigated or rainfed wetland environments during the tillering stage of the rice plant. It has also been reported in upland and deepwater rice. Its population density is favored mainly by cloudy or rainy weather, cultivation of high-tillering varieties, intensive management practices, and low parasitization.
The adults are nocturnal. They are easily collected using light traps. They mate soon after emergence. Each female midge mates only once. It can lay as many as 100-200 eggs in its lifespan of 4 days. The male midge lasts for 12 to 18 hours soon after emergence.
The eggs are laid either singly or in groups of 3-4 at the base of the plant, on the ligule, on the leaf blade, or on the leaf sheath. Egg incubation is 3-4 days. The neonate larva or maggot eventually locates the growing point of the apical or side buds at a node in order to feed. Its feeding damage causes formation of a tubular gall at the base of the tiller and inhibits growth of the leaves and panicles. The gall enlarges at the base of the tiller as a result of the continuous feeding of the maggot.
Larval and pupal development is completed inside the gall. One maggot occupies one tiller. Three to four larval stages are observed in 15-20 days. Pupation is 2-8 days. Before adult emergence, the pupa uses its abdominal spines to reach the top of the gall. It makes exit holes for adult emergence.
During the dry season, the insect remains dormant as a pupa in dormant buds of alternate hosts.
Host range
The Asian rice gall midge prefers rice and maize.
Detection and inspection
Its mosquito-like structure and the colors of both the male and female adults easily identify the Asian gall midge. The rice field can be observed and checked for the presence of onion leaves and silvershoots resulting from tubular galls formed at the bases of rice tillers. Tillers with tubular galls can be dissected for larvae and pupae.
Management
Cultural control
In general, plowing under ratoon of the previous
crop can help reduce infestations.
Biological control
Several natural enemies combat the Asian rice
gall midge. Both the egg and larva are parasitized by Obtusiclava oryzae
(Subba Rao), Platygaster oryzae Cameron. The larval parasitoids include Eurytoma
setitibia Gahan, Neanastatus cinctiventris Girault, N. oryzae Ferriere,
Propicroscytus mirificus (Girault), Tetrastichus sp. nyemitawus
Rohwe. and
Trichorpia sp. N. oryzae and N. cinctiventris also parasitize the pupal stage.
The eggs are fed upon by phytoseiid mites Amblyseius imbricatus Corpuz, whereas the adults are eaten by spiders such as Argiope catenulata (Doleschall), Neoscona theisi (Walckenaer), and Tetragnatha mandibulata (Walckenaer).
Host-plant resistance
In India, rice cultivars Eswarakora, HR42, HR63,
Ptb 18, Ptb 21, Siam 29, and Thai variety Leuang 152 resist the rice gall midge.
Chemical control
It is difficult to control the gall midge with
insecticides.
Selected references
Barrion AT, Litsinger JA. 1994. Taxonomy of rice insect pests and their arhropod parasites and predators. In: Biology and management of rice insects. Manila (Philippines): International Rice Research Institute. p 13-362.
Dale D. 1994. Insect pests of the rice plant. In: Biology and management of rice insects. Manila (Philippines): International Rice Research Institute. p 363-486.
Katanyukul W, Kadkao S, Boonkerd S, Chandaraprapa N. 1980. Rice gall midge outbreaks in Thailand. Int. Rice Res. Newsl. 5(2):13-14.
Pathak MD, Khan ZR. 1994. Insect pests of rice. Manila (Philippines): International Rice Research Institute. 89 p.
Reddy DB. 1967. The rice gall midge, Pachydiplosis oryzae (Wood- Mason). In: The major insect pests of the rice plant. Proceedings of the Symposium at the International Rice Research Institute, Sept. 1964. Baltimore, Md. (USA): The Johns Hopkins Press. p 457-491.
Rao PRM, Prakasa Rao PS. 1989. Gall midge (GM) outbreak on dry season rice in West Godavari District, Andhra Pradesh (AP), India. Int. Rice Res. Newsl. 14(5):28.
Reissig WH, Heinrichs EA, Litsinger JA, Moody K, Fiedler L, Mew TW, Barrion AT. 1986. Illustrated guide to integrated pest management in rice in tropical Asia. Manila (Philippines): International Rice Research Institute. 411 p.
Shepard BM, Barrion AT, Litsinger JA. 1995. Rice-feeding insects of tropical Asia. Manila (Philippines): International Rice Research Institute. 228 p.
Soenarjo E. 1986. Parasitoids of the rice gall midge (GM) in Indonesia. Int. Rice Res. Newsl. 11(5):29.
Van Vreden G, Ahmadzabidi AL. 1986. Pests of rice and their natural enemies in peninsular Malaysia. Wageningen (Netherlands): Centre for Agricultural Publishing and Documentation (Pudoc). 230 p.