Integrated pest management of Drosophila suzukii
The arrival in Europe of Drosophila suzukii Matsumura in 2009 deeply changed the pests control in cherry, small fruits and grapevine. The management of D. suzukii is very complex since eggs are laid inside the ripening healthy fruits and the larvae develop inside fruit pulp. Current controls of D. suzukii rely primarily on the application of a range of insecticides, such as pyrethroids, organophosphates and spinosyns, mainly focused on preventing the presence of adults before and during the ripening period. Due to its wide host range, rapid development rate and high dispersal ability, the chemical control against D. suzukii it is not sufficient to prevent damage and often do not provide effective results. Moreover, in order to avoid insect resistance, the risk of residues in fruits and negative side effects on environment, it is very important to optimize the use of the insecticides. It is, therefore, necessary to implement IPM strategies providing the disadvantage to the insect development and increasing the effectiveness of insecticide applications.
First of all it is important to adopt in the orchard all the cultivation and agronomic practices suitable to avoid a cool humid microhabitats favorable for D. suzukii development. Winter and green pruning it is necessary to open up the canopy to increase airflow to the canopy and reduce shading in the inner part (facilitating also the insecticide coverage). In addition, the use of mulches reducing standing water can further contribute to the reduction of humidity in fruit orchards.
Moreover during the ripening season, sanitary measures such as clearing ground, removal of dropped and over-ripe fruits it is necessary. Larvae inside removed fruits have been effectively killed by solarisation. Infested fruits can either be placed on the ground in a sunny location and covered with clear plastic sheeting or placed in sun exposed plastic bags for at least 2 days.
Besides sanitary measures, the use of nets (mesh of about 1 mm2) covering fruit bearing trees or shrubs is an effective complementary method to physically exclude D. suzukii. Nets need to be installed before the fruits begin to ripen to prevent any SWD being trapped inside the nets.
The mass trapping technique can contribute in pest control, traps were placed in the border every 4–6 m at a height of 1.5 m The best catches were achieved using a mixture of brown sugar (50 g) vinegar (50 mL), wine (150 mL) and water (300 mL).
The pest management should be implemented also in the surrounding areas in order to reduce D. suzukii reservoirs as much as possible.
Hopefully, the introduction of additional biotechnological and biological approaches would further implement the control strategies for D. suzukii infestation.
On the all, to design a rational control strategy it is essential an area-wide and prompt monitoring of females and eggs. Given the bio-ecology of D. suzukii, the integration of all management tools is necessary for and effective control.
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