Exploitable results
Aim of the research was to develop existing rearing facilities in Egypt and Tunisia to European standard. Activities improved output of production and working conditions for technical staff. First step was the stabilizing of physical conditions in the production area of the particular rearing host (Sitotroga cereallela in Egypt and Ephestia kuehniella in Tunisia). Composition and preparation of host diet were modified.
An increased output of host eggs was caused by these measures. Hygiene protocols were developed and implemented to prevent any contamination with pests and allergic reactions of the rearing staff. Handling procedures for the Trichogramma-rearing were optimised in both mass rearing units, in particular for the simultaneous production of several strains. Protocols for quality control of the product were developed and implemented. Close cooperation between partners in Egypt and Tunisia will continue after the project in order to establish an efficient mass production unit in Tunisia.
The technical standard of these units for the production of beneficial arthropods can act as model in the North-African region and can help to promote and implement biological control also in other pest management programmes of this area.
An effective pheromone trap was developed to monitor the Jasmine moth Palpita unionalis population in all the participating olive growing countries. Essential information about population density, start and end of the moth flight periods in relation to the phenology of the olive tree as well as to the particular habitat was obtained. The jasmine moth was caught sporadically in Portugal, Tunisia and Greece, however since the moth migrates population outbreak occurs periodically in these countries and the monitoring of the moth population is recommended.
In Egypt the moth was collected frequently, where continuous captures with several peaks suggested an overall seasonal activity of this insect. The improved pheromone dispensers and traps for P. unionalis are now commercialised by NoVagrica Hellas S.A. and used in Greece and other countries.
Inquiries conducted in Portugal, Tunisia and Egypt demonstrated the high level of interest among olive farmers for biological and biotechnical control methods, but revealed also the need for more demonstration and training. Though many efforts to introduce integrated pest management practices into olive cultivation were performed by plant protection authorities, the farmers do not implement all recommended measures. They have a high interest in biological/ biotechnical methods, but do not have sufficient information on available techniques. The data can be used as a first hint to optimise advisory activities.
Insecticides used currently in olive cultivation were evaluated for potential side-effects on the egg parasitoid T. cacoeciae March., following IOBC-guidelines. Insecticides used at the field recommended rates differed in their initial as well as residual toxicity. Deltamethrin (2.5%) was the most toxic compound to the adult and pupae of T. cacoeciae and the most persistent one, while Malathion was the least toxic compound to the adult and pupae of T. cacoeciae and the least persistent one.
The two mineral oils reduced parasitism up to 25% and were therefore rated as harmless to the adult stage of the parasitoid. Harmful and persistent chemicals pose particular risks for many key parasitoids and predators, especially those that are active in the olive groves through the whole season. Short-lived preparations like mineral oils and Malathion are likely to have much less total impact on natural enemies than persistent ones and are therefore more suitable for use in integrated plant protection. Results can be used to outline guidelines for insecticide application in olive cultivation.
Natural clays absorbed sensitive organic chemicals protecting them from photo oxidation, regulating the release rate and have been used as carriers for many agrochemicals. Montmorillonite common natural clay was proved effective substrate for the slow release formulation and UV protection of the sex pheromone components ((E)-11-hexadecenal and (E)-11-hexadecenyl acetate of the jasmine moth, Palpita unionalis. The release rate of the two pheromone components tested under field conditions exhibited a first-order release rate for the E-11-hexadecenal, but a more constant release rate for the E-11-hexadecanyl acetate.
The efficacy of the mating disruption against the jasmine moth population was evaluated for three consecutive years in a highly infested olive plantation near Cairo/Egypt. The application of 80g/ha of the formulated pheromone resulted in a male disorientation around 90%, the egg lying by female was reduced on the treated site in comparison to the control, but several mated females were still present.
The method would be mainly suitable for isolated, densely planted olive plantations like the experimental farm in Egypt. It will certainly be possible to strongly reduce the current costs of the pheromone application after further progress towards commercialised production.
Different habitat management strategies were tested in case studies in Portugal (elevated, semi-arid area in Southwest-Europe) and Egypt (North-African desert area) to create ecological infrastructures in the olive grove ecosystem. Created vegetation islands, composed of flowering vegetables in Egypt and of flowering buckwheat/carrot or natural vegetation in Portugal were evaluated for their impact on important groups of beneficial arthropods. The abundance and diversity of these taxa was increased in the treated areas in comparison to plots kept without vegetation.
The omission of soil tillage resulted in the development of natural soil vegetation and modified the composition of the soil fauna. Increasing the secondary vegetation by these measures lead to a significant attraction of the beneficial fauna. Further research on population dynamics of both pest and beneficial species is required to explore a potential long-term effect for sustainable pest control. In Egypt, workers adopted the suggested strategy and used the vegetables for their daily subsistence and local markets. But costs and benefits of such farming practice need to be evaluated in detail.
Also research is focussing on further environmental benefits, potentially arising after increasing the vegetational diversity in the olive grove ecosystem (e.g. prevention of water-run and soil erosion) need to be considered in future studies.
Indundative releases of mass-reared Trichogramma-wasps were performed in Portugal, Tunisia, Greece and Egypt. Two to three releases were usually carried out during the anthophagous and during the carpophagous generation of the olive moth in Portugal, Greece and Tunisia. In Egypt, up to 10 releases were performed from early spring on due to the permanent presence of the jasmine moth. Best results were obtained by several releases of 9000 wasps/tree in two-weekly intervals in the olive plantation in Egypt, using native Trichogramma-strains. Ant predation on releasing units revealed to be a major factor impeding successful release.
Further research effort is needed to improve releasing devices and to define the essential doses of wasps in order to reduce costs of the application. After optimisation, the inundative release of mass-reared Trichogramma can be an effective tool for biological control of the carpophagous generation of the olive moth, which can currently be treated only by insecticides. The jasmine moth is a secondary pest with increasing importance, especially in new olive plantations with artificial irrigation. Releases of Trichogramma in such biotopes may help to suppress the jasmine moth population to tolerable levels.
Sex pheromones are chemicals secrete by female insects to attract male mates of the same species. Pheromones are used for monitoring insect populations, mass trapping and mating disruption. Mating disruption, as practiced in olive integrated pest management program, involves flooding an olive grove with large amounts of the sex pheromone to prevent potential mates from locating one another and mating.
The pheromones are released from devices that are spread in the field. Based on developed slow release formulation technology in NCSR "D", the main pheromone component (Z)-7-tetradecenal was encapsulated into ?-cyclodextrin powder. The release rate of the sex pheromone was optimised to use in a wider range of climatic conditions. The formulation of the main pheromone component (Z)-7-tetradecenal into a ?-cyclodextrin-complex and its application in polypropylene tubes at a rate of 40g (a.i.) per hectare resulted in stable and sufficient release rates of the pheromone up to 2 months field exposure, in a vast range 20-35oC of temperature. Excellent male disorientation (> 90%) was reached in all four countries tested (Greece, Portugal, Tunisia and Egypt. Population density (as fruit infestation) and also fruit fall were significantly reduced in treated areas (efficacy > 60%) and yield/tree was increased (> 58%).
Field collections of native egg parasitoids of the genus Trichogramma were done by host egg exposure in several olive groves. The following species were recorded: T. cacoeciae, T. sp. nr. nerudai in Portugal; T. oleae, T. cacoeciae and T. bourarachae in Tunisia; T. cacoeciae in Greece; T. bourarachae, T. euproctidis and T. cordubensis in Egypt. Suitable strains/species were selected in laboratory tests by considering their host preference; efficacy in searching target host eggs on olive foliage and tolerance to heat. Strains that were collected from olive groves were superior to those collected elsewhere, confirming the assumption that biological control agents should preferably be isolated from the relevant pest-crop system.
The Mediterranean species T. cordubensis and T. bourarachae showed particular potential to be used in biocontrol programmes in this region. The use of indigenous Trichogramma-strains for biocontrol has the added advantage of following recommendations made by the EPPO (European and Mediterranean Plant Protection Organization) on "Safe use of biological control" (EPPO 2002). The species T. bourarachae and T. cordubensis are typical species of the Mediterranean region and our results encourage further testing of these species also for use in other biocontrol programmes.
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