Impact of Pesticides Used in Citrus Orchards on the Beneficial Insect Cryptolaemus montrouzieri Mulsant (Coleoptera'. Coccinellidae)

摘要

Adults and larvae of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae), a predator of the mealybug Planococcus citri Risso (Hemiptera: Pseudococcidae), were exposed to direct sprays and to leaf discs treated with malathion, acetamiprid, cyhexatin+tetradifon, methidathion, and spinosad. Active substances were very toxic when directly sprayed on larvae with mortality rates around 80.0% except for spinosad, which was less toxic (39.0% mortality). Direct spray of adults caused mortality ratesranging from 100% for acetamiprid to 18.8% for spinosad. On treated leaf discs, larval mortality rates varied between 73.0 and 84.0% except for spinosad that showed 48.0% mortality only. On adults, acetamiprid and methidathion resulted very toxic with mortality rates higher than 70.0%, whereas malathion, cyhexatin+tetradifon and spinosad caused mortalities of 47.5, 31.0 and 18.8%, respectively. Based on these results, spinosad is much less harmful than the other pesticides and could be compatible withreleases of the coccinellid C. montrouzieri.