One of the major crop pests found in Asia is the gall midge. The gall midge is a small fly that lays its eggs in flower buds. When the eggs hatch, tiny worm-like larvae emerge that damage the young bud, causing it to fall to the ground. There are various types of gall midges that damage particular target species. The rose midge infests young buds and shoots of roses and is a serious pest in greenhouse. Some other serious pests are the wheat midge, sorghum midge, rice midge, clover midge, and pear midge.
The larvae of these pests cause severe crop damage during the vegetative stages by producing tube-like ‘silver shoot’ or ‘onion leaf’ galls that prevent panicle production. Severe yield losses are reported due to these pests that vary significantly depending on the climatic zone, ecosystem and level of cropping intensification. In the face of increasing human population and rapidly growing demand for food grains, the alleviation of insect-induced food-grain losses has to be tackled to ensure food security of the large number of people in Africa who depend on crops. The damage due to these pests can also kill individual shoots. Repeated attacks can cause brooming, a proliferation of shoots at the ends of the twig and disfigured growth. Besides reducing the yield, the damage is unsightly and can lower the aesthetic value of ornamental trees.
Losses as high as 25–80% in farmers’ crops have been recorded in some fields. The larvae attack the growing points of tillers and cause the leaf sheath tissues to form a tube-like structure called a ‘silver shoot gall’ that resembles an onion leaf. Early gall infestation results in stunting, bushy appearance of the plant, with as many as 50 small tillers per hill. In Orissa, India, yield losses due to the gall midges ranged from 0.06 to 1.1% for every unit percent increase in silver shoots. Another trial reported that infestation was reduced to 19% as compared with 39.6%. It was reported that the presence of even 5% silver shoots decreased yields by 37%. Blueberry gall midge occurs sporadically, but when present, they can cause reductions of 20 to 80% flower buds or fruit.
The below article would better explain the damage caused by these pests.
Cereal crops at risk of saddle gall midge attack
21 December 2012
Not all of the limitations and threats facing the UK wheat crop are familiar and established ones, Caroline Nicholls, HGCA research and knowledge transfer manager told the HGCA Agronomists’ Conference.
Outlining the HGCA-funded research on saddle gall midge, she said: “During the past three summers, we have been working with cereal growers to identify the extent of the threat posed by saddle gall midge, which before 2010 had been relatively unknown in the UK since the last significant damage was reported in the 1970s.”
The pest was generally more prevalent in central and northern Europe. The early stages make themselves apparent in the form of red-orange larvae in the soil, and red/orange eggs later lay mainly on the younger leaves of wheat plants.
Once hatched, the larvae can be seen by peeling away the leaf sheath beneath the saddle-like galls that become apparent on the stems. The biggest impact of these is the node decay they cause.
“Since 2011, we have been working with ADAS, AICC, Dow AgroSciences and cereal growers to produce a review of the pest’s biology and a strategy for control. Crops most at risk are those where stem extension coincides with larval feeding, particularly in late and spring-sown wheat and barley. Heavy land and under-continuous cereals are also affected,” said Ms Nicholls.
Information is available from HGCA on identification and control, with early sowing and the wider use of break crops among the key factors in regularly affected areas.
There are no insecticide label recommendations for control of saddle gall midge, but organo-phosphates and pyrethroids have been shown to give good control.
Application timing is crucial, though – treatment must be made before the larvae move beneath the leaf sheath.
Chemical control of this pest is not a viable control option because the destructive larval stages live within the plant. Use of unnecessary synthetic insecticides increases the risk of disturbing the natural ecological balance. Thus we need a solution which would effectively keep the gall midge population in check, keeping them away from our crops, while at the same time not having any negative impact on the environment.
C Tech Corporation offers a product called Termirepel™, which is a non-toxic, non-hazardous, environmentally safe insect repellent. It can repel more than 500 species of insects on account of it being a broad spectrum anti-insect repellent. The most striking feature of Termirepel™ is that it neither kills the target species, nor the non-target species. It will simply keep the insects away from the application. This product is available in masterbatch and lacquer form, and as a liquid solution. Termirepel™ can be added in mulches or incorporated in agricultural bags and films, which could be used to keep our grains safe and guarded against the pesky gall midges!