Efficacy of local food baits in fruit fly management and estimation of infestation indices of fruit flies in guavas in Maputo, Mozambique

Abstract

Fruit flies (Diptera:Tephritidae) are serious pests of crops, requiring effective monitoring tools to guide management. This study evaluated the attractiveness of local food baits for monitoring fruit flies in guava orchards in Maputo Province. Additionally, the study assessed guava infestation levels, examined the relationship between trap catches and adult emergence from fruits, and analyzed how climate variables and fruit availability influence fruit fly population density. A randomized block design with four treatments (palm sap, molasses, torula yeast, and water) and four replications was used. Four trees per block were randomly assigned baited Tephri traps, which were inspected weekly. Collected flies were counted, sexed, and identified. Simultaneously, guava fruits from trees and the ground were sampled weekly, incubated, and examined for pupal and adult emergence to estimate infestation indices. Three genera were trapped: Bactrocera, Dacus, and Ceratitis, with Bactrocera dorsalis dominant (90.37%). Torula was the most attractive bait (FTD = 4.15±0.804), followed by palm sap, with no statistical difference. Molasses and water were least effective. Fruit fly population fluctuations were strongly linked to fruit availability and temperature. Guava fruits exhibited high infestation, averaging 245.06±16.10 pupae/kg and 208.46±13.34 adults/kg. A significant positive correlation (r = 0.652, p = 0.0297) was found between trapped B. dorsalis and emerged adults, with regression analysis showing trap catches explained 42.5% of emergence variation suggesting that factors external to the orchard have a greater influence on infestation. Overall, the results showed that palm sap is a promising, low-cost alternative bait, and highlighted the importance of orchard sanitation as well as the need to consider area wide fruit fly management strategies in order to reduce infestation