Persian Journal of Acarology

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% concentration 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.

Abstract The aim of this study was to evaluate acaricidal activity of Melia azedarach L. ripe fruit extract against Dermanyssus gallinae (De Geer, 1778) under laboratory conditions. For this purpose, hexanic ripe fruit extract of this tree at concentrations 0.25, 0.5, 1, 3, 5 and 10% were prepared with acetone as solvent and treatment groups exposed to these concentrations using Petri dish residual film bioassay method. The positive control was carbaryl while negative control was acetone. The bioassay was repeated five times. The mortality rate of mites in treatment and control groups were assessed 24 h post exposure. All treatment groups showed significantly higher mortality compared to the negative control group (P < 0.05). All concentrations of extract showed moderate or high miticidal effects on D. gallinae as mean mortality of exposed mites to concentrations 0.25, 0.50, 1, 3, 5 and 10% were 40, 43, 60, 62, 79 and 100%, respectively. Carbaryl as a positive control caused 100% mite mortality at 1 mg/ml concentration. The LC50, 90, 99 (lethality concentrations for 50, 90 and 99%) values of this extract were calculated and were 1.78, 5.93 and 9.32%, respectively. The results of the current study revealed that the ripe fruit extract of M. azedarach was highly toxic to D. gallinae.