Pest-specific chemical strategies for the management of Aleurocanthus spiniferus (Quaintance, 1903) in mandarin orchard supported by on-site chlorophyll assessment

Abstract

In southern Montenegro, Aleurocanthus spiniferus (Hemiptera: Aleyrodidae) is an important Citrus pest. A field experiment was conducted in a Satsuma mandarin (Citrus unshiu Marcow.) orchard to evaluate the efficacy of chemical treatments for A. spiniferus control and to assess impact induced by this pest in plant leaves using portable chlorophyll meter-SPAD. Two insecticide applications were carried out, the first in June and the second in August in 2024 and 2025. During the first treatment in each season among all tested insecticides, deltamethrin, spirotetramat, pyriproxyfen and acetamiprid, the last mentioned showed the highest efficacy 7 d after treatment for larvae. During 2024, in the second treatment, pyriproxyfen showed highest efficacy of more than 91% 7 and 14 d after treatment, while acetamiprid showed the highest efficacy of more than 95% during the second trial in the second year. Spirotetramat showed high efficacy towards eggs in all except the first assessment during the first season. After both assessments in 2025, SPAD value was measured representing the chlorophyll content in mandarin leaves. In comparison to the control variant (49.9 SPAD units), the increase in chlorophyll content ranged from 38.2% to 48.6% (69.1-74.2 SPAD units) across all tested variants. The greatest positive impact was observed in the variant with spirotetramat (48.6%). Acetamiprid (45.6%) and pyriproxyfen (47.6%) values were also highly positive, while the smallest effect was recorded for deltamethrin (38.2%). The obtained results are consistent with high insecticide efficacy, i.e., the decreased chlorophyll levels within the control variant were caused by the higher pest infestation.