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New female selective attractants for medfly


The Mediterranean fruit fly Ceratitis capitata is a major pest of the fresh frui t industry and is considered as a key agricultural pest in many parts of the wor ld. It attacks most citrus varieties, deciduous and subtropical fruits as well a s some vegetables. All the Mediterranean Basin countries, growing medfly host pl ants, suffer of its damages. Certain countries free of the medfly (U.S. most fa r-eastern countries, parts of Australia, some European countries), which are act ual/potential target markets for import of fresh fruits and vegetables, activate strict quarantine regulations against it. The most efficient currently used con trol system against the medfly is spraying a poison-bait mixture. Traps containi ng the powerful male attractant trimedlure are being used to monitor the medfly populations. Two additional environmentfriendly (EF) control systems are being s tudied and partly used - the mass 'lure and kill' trapping and the Sterile-insec ttechnique (SIT). In both systems female food lures are used as baits for traps. The bait presently used in control systems against the medfly is a liquid prote in hydrolysate intended to attract mainly females. Since the discovery of mcphai l (1939) on the attractiveness of such materials no breakthrough was reported. T he attractiveness of some commercial baits is no higher than that of some common ly used manures and fertilizers. New, more efficient baits are needed for contro lling the medfly. No female attractant(s) of similar power to trimedlure (for ma les) is known. Since the females are the fruit damaging population is the genera l goal of the project the development of female specific attractant(s). The prop osed development of an improved bait is based on the attraction of medfly to amm onia.

This general goal will be achieved by means of the following specific objectives and tasks:
( 1 ) the development of an alternative commercial bait for control systems against the Mediterraean fruit fly;
(2) to strengthen the attractiveness and the females-selectivity of these baits;

(3) to determine the efficacy of the new baits used in traps;
(4) adapting the product to poiso n-bait spray application;
(5) to determine in large scale field trials the eff icacy of a new to be developed lure and kill mixture in aerial sprays in Israel and in Greece.

This proposal brings together one private firm and three R&D public institutions from two European countries and Israel. All of them have a g reat deal of experience working on either Mediterrenean fruitfly and the impleme ntation of biological control methods. The composition of the research teams (in dustrial and laboratory chemist, insect biologists and physiologists, basic and applied researchers, extensionists, field workers) guarantee a multidisciplinary and realistic approach and the practical application of the results. The proje ct fits within area 4.4.1 Plant & Health: Control methods or eradication methods for quarantine organisms.
In all the commercial protein insect baits the presence of pyrazines is found. For the first time pyrazines of the same nature as in the common commercialproteinaceous insect baits have been found in a steep water liquor product in solid spray dried form. It has been proved by field trials that a blend of pyrazines contributes to the attractiveness of the common baits and also in the ammonia based dispensers, but some other factors are responsible for the high efficiency of hydrolyzed proteins. The volatiles from various hosts (fruits) of the medfly at various ripening stages have been analyzed. Clear differences in the composition of the terpenes between the green and the ripe fruits have been found. A systematic study shows that these compounds are formed after an attack by the Mediterranean fruit fly or even after a mechanical damage of the skin of the orange. Analysis of the head space volatiles from two common hosts of Ceratitis capitata, orange fruits and apricots at various ripening stages showed further that apart from a variation of the volatiles blend as ripening progress, the presence of some components are related with the oviposition stings of the medfly.

The project has not used photoactivated poisonous food colors because of the problems foreseen with registration of the product when successful. In the project Spinosad, a commercial insecticide, has been used instead. The Entomella + spinosad combination gave in the lab the best fruitfly mortality during the first few days of the experiment. Dispensers with controlled release of ammonia were made in different shapes and tested in outdoor and indoor exposure experiments. Ammonium salts packed in small plastic bags gave the most steady release in time but also rod and plate dispensers lasted for more than 5 weeks. TNO developed a sprayable attractant for use on the fabric material in the field trials of IMBB. Since the paper trap is much more convenient to handle the formulation of the sprayable has been adapted to the much smaller volumes of liquid used. Lure and kill field application with the above combination on green paper panels or with McPhail Biolure-DDVP, suggested good possibilities for effective medfly biorational control, especially in the very sensitive and important for many host crops period of May-August. For practical methodology development, further experimentation is needed. A combination with the sprayable TNO formulation might be very attractive. An extraordinary weather pattern in winter-summer of 2002 (exceptionally cool and rainy), clearly indicated that medfly population build up and crop infestation between spring-summer depends largely on weather.


De Wielen 6
5612 Eindhoven

Participants (3)

Vassilika Vouton
711 10 Heraklion

50250 Bet Dagan
Viltaniotis Street 36
145 64 Kifisia - Athens