Mechanical distribution of predator in biological control in protected crops

The widespread indiscriminate use of highly persistent and toxic plant protection pesticeds has, over a long period of time, highlighted the negative aspects of the chemical protection of crops (direct toxic effect, accumulation of residues at the top of food chains, ecological impairment caused by aquifers pollution, etc). The distribution of benificial insects and mites on crops without doubt represents a crucial phase for the correct application in biological control strategies and at the same time the most critical as the particular biological characteristics of useful insects must always be taken into consideration. The application of the biological method of phytophagous control has a number of advantages linked particularly to: a) greater respect of the environment; b) the safeguarding of the health of agricultural operators; c) the quality of the produce. Furthermore, as well as being envisaged in a number of public or private disciplines, biological control represents the only means of averting the chemical resistance phenomena without resulting in incidents of phytotoxicity in non-targeted living organisms as well as man. Distribution is usually carried out manually and is quite a demanding task for the operator. In addition to aspects linked to the inexpensiveness of this type of intervention, the manual distribution of living organisms also affects the efficiency of the distribution of the useful insect above all if it is not very mobile or in particular biological phases. Indeed, special attention must be given to the choice of distribution quantities (which differ for each organism released and depend on the crop and type of breeding) and the uniformity of distribution which varies also in relation to the size of the plants in question and the plant layout. The use of an operator can be considerably reduced by substituting manual with mechanical distribution, resulting in higher work capacity, improved intervention speeds and reduced running costs compared with manual means. Key word: , biological control systems.