Biological cycle of Oligonychus coffeae (Acari: Tetranychidae) on alder and coffee, and the acaricidal effect of their ethanolic extracts against the red spider mite.

Abstract

The coffee red mite, Oligonychus coffeae (Nietner), is a pest of major agricultural importance in tropical regions. This study evaluated the in vitro effect of two host plants, coffee (Coffea arabica) and Andean alder (Alnus acuminata), on the biological cycle and population parameters of O. coffeae under controlled conditions (25 ± 1 °C, 70 ± 5 % RH, and a 16:8 h photoperiod). In addition, the acaricidal activity of ethanolic extracts of coffee and alder at concentrations of 5, 10, and 20% (w/v) was assessed using a leaf-dip bioassay, with mortality recorded at 24, 48, and 72 h and compared with a synthetic acaricide (propargite). The development of O. coffeae was significantly faster on coffee leaves (13.8 days) than on alder (16.2 days); however, fecundity and adult longevity were higher on alder, reaching 59.9 eggs per female. Population parameters were significantly higher on alder (rₘ = 0.254 day−¹; R0 = 52.4 female eggs/female), indicating a greater population growth potential on this host. The ethanolic extracts exhibited dose- and time-dependent acaricidal activity; at 72 h, the 20% concentra tion caused mortalities of 91.2% on coffee and 89.3% on alder, comparable to propargite. These results indicate that both host plants favor the development of O. coffeae and that their ethanolic extracts represent promising alternatives for the integrated management of this pest.