Efficacy of Aspergillus oryzae strains in reducing Thaumatotibia leucotreta damage and improving postharvest quality of avocado fruits

Abstract

Avocado productivity is strongly constrained by insect-mediated fruit damage, because feeding injury reduces marketable yield and can also compromise postharvest quality. Field trial was purposively conducted in 3 districts growing Hass avocado namely Siha, Moshi and Hai. The minimum farm size was 2800 m 2 which was enough to provide a minimum of 30 plants to carter for one set for the treatment which was replicated thrice. A randomized complete block design was used with six treatments namely; Aspergillus oryzae- JF20, JF21, JF22, JF23, JF24 at concentration of 4. 0 × 10 8 conidia/mL in 4 mls/Litre and 6-negative control, whereby only water was applied without addition of any form of insecticide. In the present study, the unsprayed control consistently showed the greatest fruit damage across all three sites, reaching 2.95 ± 0.069 in Siha, 3.88 ± 0.067 in Moshi, and 3.35 ± 0.186 in Hai, which establishes a clear baseline of vulnerability under untreated conditions. This pattern indicates that, avocado orchards without protection remained highly exposed to damage associated with False Codling Moth, Thaumatotibia leucotreta. The magnitude of control damage also underscores the agronomic importance of interventions that can suppress pest injury while maintaining orchard productivity. Fruit damage is not only a direct loss of harvestable produce but also a pathway to reduced economic value through lower grades and shortened shelf-life. This framing is important for interpreting the treatment effects in a production system where pest suppression, yield formation, and quality preservation are functionally linked increasing export value for avocado.