Lacewing larvae (Mallada basalis; Neuroptera: Chrysopidae) as potential biocontrol agents against greenhouse thrips (Heliothrips haemorrhoidalis; Thysanoptera: Thripidae): stage-specific predation, prey stage preference, development, and survival.

Understanding predator-prey interactions at different developmental stages is crucial for improving biocontrol strategies against small, elusive pests such as thrips. The greenhouse thrips, Heliothrips haemorrhoidalis (Bouché) (Thysanoptera: Thripidae), is a globally significant pest, with significant differences in susceptibility and nutritional value to predators across its developmental stages. This study conducted no-choice experiments, choice experiments, and food suitability tests of first- and second-instar green lacewings Mallada basalis (Walker) (Neuroptera: Chrysopidae) feeding on the greenhouse thrips. In no-choice experiments, the first-instar green lacewings consistently consumed more first-instar thrips and pupae than second-instar thrips and adults. Second-instar green lacewings consumed more prey overall across all developmental stages than first-instar lacewing larvae. Choice experiments further confirmed that when all thrips instars were provided, all stages of lacewings exhibited a strong and consistent preference for first-instar thrips, a moderate preference for pupae, and almost complete avoidance of second-instar thrips, indicating that lacewings actively choose their prey. Food type significantly affected lacewing survival and development. Lacewings feeding on moth eggs all survived and developed rapidly, while lacewings feeding solely on thrips, although able to complete development, had a prolonged developmental cycle and increased mortality. In contrast, lacewing larvae feeding on Carpoglyphus lactis (Linnaeus) (Sarcoptiformes: Carpoglyphidae) failed to develop beyond the early instars, suggesting that despite initial feeding, the nutritional value was insufficient. This study highlights the importance of integrating behavioral and nutritional perspectives when assessing predator biocontrol, and provides mechanistic insights into the role of M. basalis in greenhouse thrips population management.