Bio-insecticide effect of isolates of<i>Fusarium caatingaense</i>(Sordariomycetes: Hypocreales) combined to botanical extracts against<i>Dactylopius opuntiae</i>(Hemiptera: Dactylopiidae)

Dactylopius opuntiae, cochineal scale, is one of the most important pests in the production of the prickly pear Opuntia fícus-indica (Caryophyllales: Cactaceae). The use of entomopathogenic fungi and botanical extracts, which may act additively or synergistically, are options for the control of D. opuntiae. In this study, we evaluated the effectiveness of combinations of Fusarium caatingaense (Sordariomycetes: Hypocreales) isolates with extracts of Nicotiana tabacum (Solanales: Solanaceae) (tobacco) and Paubrasilia echinata (Fabales: Fabaceae) (pau-brazil) against D. opuntiae. Aqueous and hydroethanolic extracts at 5%, 10% and 20% w/v concentrations were evaluated for compatibility with F. caatingaense isolates, and compatible treatment combinations were tested for insecticidal activity against adult D. opuntae females. The treatments with greatest mortality against cochineal scale were tested in greenhouse. When applied alone, N. tabacum extracts were more effective compared with extracts from P. echinata. The insect mortality caused by the combination of F. caatingaense isolates with aqueous extracts of P. echinata did not differ from their use independently. However, an increase in mortality of cochineal scale was observed for URM 6778 and URM 6779 isolates when combined with the aqueous extract of N. tabacum at 5% and 10% (w/v) respectively. The combination of the URM 6779 with the 10% aqueous extract of N. tabacum (w/v) was tested in a greenhouse, resulting in 98.7% mortality of the cochineal scale, supporting the need for further field trials.