Rainfed rice - IRRI books - International Rice Research Institute

RAINFED RICE A SOURCEBOOK OF BEST PRACTICES AND STRATEGIES IN EASTERN INDIA
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Rice gall midge
Rice gall midge (GM), Orseolia oryzae (Wood-Mason) (Cecidomyiidae:
Diptera), earlier called Cecidomyia oryzae and Pachydiplosis oryzae,
causes severe damage during the tillering stage of the crop. Yield loss
from rice GM damage varies from 3% to 70%. The maggot-like larva
feeds inside developing tillers, causing their base to swell as galls.
Reasons for outbreaks of gall midge
Early monsoon showers following a dry spell
Continuous cloudy weather associated with intermittent rains
High relative humidity
Late planting
The increased incidence of gall midge in recent years can be attributed to
the following reasons:
Spread of high-yielding susceptible varieties
Continuous cropping
High nitrogen application
Closer plant spacings
Gall midge in light trap
It is well established that adult midges are attracted to light and this
behaviour can be used to monitor their activity. Females are mostly
trapped under the mercury light. This demonstrates the potential of using
light traps with different kinds of light and light intensities.
Bamboo traps with a 250-W infra-red lamp attract the maximum number
of midges, followed by 40-W incandescent light. The black-light invisible
light trap attract larger numbers of midges. The peak catch of midges
occurs between 10 and 11 p.m.
The light trap catches were correlated with different weather parameters.
In general, early rains with moderate temperature followed by heavy rain,
overcast cloudy weather and drizzle were conducive to midge incidence.
Predators of gall midge
Three carabid predators, Casonides sp., Nabis capsiformis Germar and
Ophionia indica Thumb were found to prey upon larval, pupal and adult
stages, while a mite, Amblyseius sp., was predatory on eggs.
Parasitoids as biocontrol agents
The egg-larval parasitoids, Platygaster oryzae Cameron (Platygasteridae:
Hymenoptera), are highly effective in reducing the population of gall
midge in nature. The occurrence of this parasitoid is higher in the
successive rice crop. The adult parasitoid is black or yellowish brown and
measures about 1 mm. Resistant varieties are Shakti, Heera, Neela and
Shaktiman.