Virulence of Metarhizium anisopliae (Deuteromycotina : Hyphomycetes) on Anastrepha ludens (Diptera : Tephritidae): Laboratory and field trials

Twenty isolates of the fungus Metarhizium anisopliae (Metsch.) Sorkin (hla) were evaluated to determine their virulence against last instal. and adult emergence of Mexican fruit fly, Anastrepha ludens (Loew). Larvae were expo sed Ly immersion in a conidal suspension at a concentration of 10(8) UGC/ml under laboratory conditions. Larvae and pupae cumulative mortality rates r anged from 37.9 to 98.75%. Thirteen isolates caused mortality rates >83.7%, and. their LT50 values ranged fi om 1.8 to 6.2 d. Thr Ma2, Ma8, and Ma16 i solates were evaluated at seven different concentrations ranging from 10(1) to 10(7) UFC/ml, showing LC50 values from 3.7 to 1.8 x 10(5) UFC/ml. In a field-cage experiment, 200 mi of a conidial suspension of Ma2., at a concen tration of 2.5 x 10(6) UFC/ml, was applied on 2,500 cm(2) soil surface (2 x 10(5) UFC/cm(2)). The fungus reduced adult emergence, 22% fewer adults eme rging in a sandy loam soil, and 43% fewer in loam soil, compared with the c ontrols. hi. anisopliae may offer a preferable alternative to chemicals as a biological control agent against A. ludens.