Diet-Induced Developmental and Morphological Plasticity in a Thelytokous Predatory Mite Amblyseius herbicolus (Chant) (Acari: Phytoseiidae)

Phenotypic plasticity enables organisms to adjust developmental and morphological responses to environmental variations, including prey availability. In this study, we investigated how variation in prey consumption influences immature development and adult morphometric traits in the predatory mite Amblyseius herbicolus (Chant). Using two laboratory-reared populations originating from Auckland and Tauranga, New Zealand, we assessed the relationship between prey consumption and immature development and morphological outcomes. While differences in prey consumption did not significantly alter developmental duration, individuals with higher prey consumption attained a larger size at maturity. Several morphometric traits, including r3 length, primary metapodal plate length, Leg III, and Leg IV, were also significantly influenced by diet, indicating that plasticity extends beyond developmental traits to morphological characteristics in A. herbicolus. Population origin also accounted for some variations in developmental and morphometric traits, although it remains unclear whether these differences arose from genetic divergence or prolonged rearing under controlled conditions. This study underscores the importance of actual prey consumption rates—rather than prey availability or density—in shaping morphological variations. It also suggests diet-induced plasticity may affect phytoseiid mite taxonomy.