LAUSR

Oligonychus yothersi (McGregor) (Acari: Tetranychidae), known as yerba mate red mite, is typically found on the abaxial face of leaves, feeding on mesophyll cell contents in yerba mate crops. Euseius concordis (Chant) is a generalist mite, feeding on other mites, pollen, and nectar, and can be a promising control agent of O. yothersi. This study aimed to evaluate development time, reproduction, survival, and sex ratio of this predatory mite when feeding on O. yothersi on yerba mate leaves. A life-cycle study was performed in a climate chamber at 22 ± 1 °C and 12 hours of photophase, 19 ± 1 °C during scotophase, and 70 ± 10% relative humidity. The study started with 36 experimental units, which were examined three times a day during immature development and once during the adult stage to evaluate reproductive parameters. Mean developmental times of egg, larva, protonymph, deutonymph, and egg-adult stages were the following: for females, 2.14 ± 0.15, 1.59 ± 0.12, 1.97 ± 0.11, 2.18 ± 0.13, and 7.88 ± 0.21, respectively; for males, 2.00 ± 0.67, 1.77 ± 0.52, 1.94 ± 0.52, 2.05 ± 0.69, and 7.75 ± 1.08. Mean pre-oviposition, oviposition, and post-oviposition periods were 3.31 ± 0.33, 10.4 ± 0.74, and 1.50 ± 0.28, respectively. Sex ratio was 0.67 and mean life expectancy was 15.22 days for females and 12.51 ± 1.91 days for males. Mean daily oviposition was 1.67 ± 0.08 eggs per female, with a mean value of 20.14 ± 1.42 eggs per female. T, Ro, rm, λ, and DT values were: 16.33, 10.03, 0.14, 1.15, and 4.91, respectively. This study demonstrated that E. concordis is a predator with potential to be used in biological control programs, successfully developing and reproducing when feeding on O. yothersi under laboratory conditions.