|Sunn pests and their control in the Near East. (FAO Plant Production and Protection Paper - 138) (1996)|
|Part II - COUNTRY REPORTS|
Eurygaster integriceps, commonly known as sunn pest, is widespread throughout the Mediterranean basin where it is a serious pest of wheat and barley. In Lebanon, it is found wherever wheat is cultivated in the coastal, middle and interior regions of the country. In the Bekaa valley, it is found from Bar Elias Torbol near Ryak to Baalbek, an area lying between the Lebanon and Anti-Lebanon mountains. When sunn pest attack is intense, damage to grain yield is comparable to that of locusts.
In Lebanon, more wheat is produced under irrigation than in the relatively arid rain-fed areas. Production may reach 7 tonnes per hectare under irrigation, while averaging only 1 to 2 tonnes per hectare under rain-fed conditions. The area cultivated with wheat during the past four years ranged from 15 000 to 20 000 ha. The main varieties cultivated in Lebanon include the soft wheats Serie 82, Hermon and Baalbek. Hard wheats cultivated in Lebanon are Stock and Sebou, while barley varieties are Litani and Rihane. Lebanon exports neither wheat nor barley, but annually imports 400 000 tonnes of wheat.
Most Lebanese wheat varieties are resistant to insects and diseases. The most important common diseases in Lebanon are yellow rust, Puccinia glumarum or P. striiformis. The most serious cereal insect pests are sunn pest, E. integriceps Put. and Aelia rostrata Boh.
THE SUNN PEST PROBLEM
The sunn pest is an extremely serious hemipteran because it affects the level of grain production as well as grain quality. The degree of damage is influenced by the severity of the winter season. Very cold winters apparently decrease the spread of sunn pest outbreaks in Lebanon. A favourable climate for sunn pest, such as high temperature and humidity, encourages outbreaks. Yield losses caused by sunn pest are difficult to determine, but damage has not been economically significant over the last few years.
The Lebanese Governments current policy is to encourage wheat production and provide assistance to farmers in order to ensure good production, including control of sunn pest outbreaks.
The sunn pest first appeared in Lebanon in 1924. During most seasons, it appears in the Bekaa valley at the onset of spring when temperatures reach 20 to 22°C. The insect arrives in the Bekaa valley from hibernation sites on the two surrounding mountain ranges, the Lebanon and the Anti-Lebanon. It reproduces in cereal fields in the valleys. Normally, sunn pest populations are higher in irrigated cereals than in rain-fed cereals. There are predatory hymenoptera attacking sunn pest in Lebanon, such as Asolcus (microphanurus) semistriatus Nees, but little is known about these.
Chemicals used in the past to control sunn pest outbreaks included trichlorfon (1 200 g per hectare), oxydemeton-methyl (1 400 g per hectare) and parathion (1 400 g per hectare). Insecticide resistance to one or more of these chemicals has been observed. Trichlorfon generally gave 85 percent control, oxydemeton-methyl gave 90 percent and parathion gave up to 90 percent. Campaigns against outbreaks were performed aerially with helicopters equipped with spray booms or by ground application using backpack sprayers. No secondary pest outbreaks were noted following the use of these chemicals. During recent years, sunn pest populations have remained low enough to make spraying unnecessary. The Lebanese Ministry of Agriculture is the only authority responsible for establishing sunn pest control programmes at the onset of a sunn pest outbreak.
Based on the current situation in Lebanon, requirements for a possible general control campaign against sunn pest are: helicopter-mounted spraying equipment; truck-mounted, powered spraying tanks; four-wheel-drive vehicles; powered individual sprayers; and pesticides.
The Ministry of Agriculture provides technicians and qualified labour as well as an entomology laboratory which is responsible for the follow-up studies on sunn pest activity in the field.
Wheat is produced in regions whose microclimate is favourable to sunn pest. The biology of the pest must be closely studied to obtain satisfactory results from control campaigns using chemical insecticides applied at the most opportune time.
A sunn pest national committee should be established in each Mediterranean country to facilitate the exchange of research results. Studies on biological control should be carried out and results compared with those of chemical control programmes. Assistance should be provided to countries with limited budgets. Scientific meetings should be organized so that experts from each country can exchange information.