The biological control of citrus mealybug (Planococcus citri (Risso)) using the Encyrtid Leptomastix dactylopii (How.) has enabled a drastic reduction in the number of insecticidal treatments in citrus fruit cultivations in Sardinia, resulting in considerable advantages of toxicological and environmental nature. In an experimental farm with approximately 12 hectares of citrus fruit orchards, in fact, the number of chemical treatments passed from an average of 4 (with a maximum of 7 in some fields) of the 1993-94 to zero treatments as from 1996 to date following the application of biological control of P. citri which was the main pest problem. Specific checks, carried out by the Residues Survey National Network during the period of maximum use of insecticides (1993-1994) had shown residues of organophosphorates (Methidathion, Quinalphos, Fenthion) on 85% of the samples examinated with values that in 10,7 % of cases resulted above the maximum limits allowed by law.

Since 1995, following the release of L. dactylopii mass-reared in the Useful Insects Rearing Laboratory of C.R.A.S. a reduction of the treated area and of the number of insecticidal treatments has resulted. The number of L. dactylopii adults released varied over time based on the results obtained, passing from 3225 per ha in 1995 to 417 per ha in 1998. The percentage of parasitism of L. dactylopii was particularly high in the autumn period involving 64% (1995) to 100% (1998) of the 3 instar of P. citri. The reduction in the use of pesticides has contemporarily favoured the action of important useful insects such as the Coccinellid Cryptolaemus montrouzieri (Muls.), released in previous years and by this time acclimatized in all Sardinian citrus growing areas, and the indigenous Encyrtids Anagyrus pseudococci (Grlt.) and Leptomastidea abnormis (Grlt.). Following the application of the biological control the production showed at harvesting a percentage of fruits infested by colonies of citrus mealybug of no more than 1%.