Toxicity of phytosanitary products to Coccidophilus citricola (Coleoptera: Coccinellidae)

Coccidophilus citricola is an important predator of Diaspis echinocacti, a scale insect that is the main pest of the forage cactus Opuntia ficus-indica cultivated in northeastern Brazil. The efficiency of a management program involving the natural enemy of an agricultural pest can be increased by adopting conservation techniques. The aim of the present study was to evaluate the selectivity of querobao, mineral oil, NatuneemTM, aqueous extract of neem leaves, and conidia of Beauveria bassiana and Metarhizium anisopliae towards the predator. Aliquots of phytosanitary products were sprayed on sections (5 x 5 cm) of cactus rackets infested with D. echinocacti obtained from forage cactus grown under greenhouse conditions. Sections were dried and offered to second-generation C. citricola adults that had been reared under laboratory conditions. Predator mortalities were assessed at 24, 48 and 72 h after application of the products or water control. Querobao and NatuneemTM were most toxic to the predator, with high levels of mortality recorded at 24 and 48 h. Conidia of B. bassiana and M. anisopliae (1 x 108 conidia mL-1) were less toxic and slower acting, with highest mortalities occurring between 48 and 72 h. The toxicities of mineral oil, neem leaf extract and M. anisopliae (1 x 107 conidia mL-1) towards C. citricola were not significantly different from the control. It is concluded that these agents may be selective to the natural enemy of D. echinocacti and could be used in combination with the predator to control this pest in forage cactus cultures.