Does long-term captivity affect the biocontrol potential of the predatory mite Amblyseius swirskii? A decade of surveillance using different populations.

Abstract

Assessing biological differences among predatory species populations is crucial, especially for those maintained long-term in captivity. This study compared three Amblyseius swirskii populations: Koppert-new, Koppert-old (kept for 10 years in the laboratory), and Biobest-new. Demographic traits of two populations (Koppert-old and Biobest-new) were evaluated using natural prey (Tetranychus urticae and Trialeurodes vaporariorum) and alternative diets (Carpoglyphus lactis and mixed pollen). In addition, the demographic traits and the ability of three populations of A. swirskii to consume the natural prey T. urticae was evaluated. Some morphological features, including idiosoma length, idiosoma width, fixed digit length, and movable digit length were measured for the three populations. The highest intrinsic rate of increase (r) for both the Koppert-old and Biobest-new populations was recorded when were fed mixed pollen. Feeding with C. lactis, T. urticae, and T. vaporariorum, in that order, resulted in the next highest values for this parameter in both populations. In the three-population comparison, the lowest r value, highest fecundity, and longest pre-adult period were recorded in the Koppert-new population. Females in this population were observed to be larger in size. This population exhibited the highest net predation rate (C₀) and conversion rate (Q_p). This study demonstrated that long-term laboratory rearing did not compromise the demographic performance of A. swirskii. Despite a lower predation capacity in the long-term reared population, its stable reproductive traits and efficient prey conversion suggest adaptive responses that help maintain population sustainability under controlled conditions.