Seasonal and Spatial Distribution of Fall Armyworm Larvae in Maize Fields: Implications for Integrated Pest...

Area of Science:

• Agricultural Entomology
• Pest Management
• Ecological Distribution

Background:

• The fall armyworm (Spodoptera frugiperda) is a significant pest impacting maize production globally.
• Understanding FAW's spatial and temporal distribution is crucial for effective integrated pest management (IPM).
• Benin's diverse agroecological zones (AEZs) present unique environments influencing pest dynamics.

Purpose of the Study:

• To assess the temporal and spatial distribution of fall armyworm (FAW) larvae in maize fields across two agroecological regions in Benin.
• To analyze FAW larval density, infestation rates, and damage severity during dry and rainy seasons.
• To determine the dispersion patterns of FAW larvae using statistical models.

Main Methods:

• Field surveys were conducted in AEZ 6 and AEZ 8, Benin, during 2021-2022 (dry and rainy seasons).
• Maize plants were randomly sampled (30-50 plants) to monitor larval density, infestation, and damage.
• Taylor's power law and mean crowding aggregation index were used to analyze larval dispersion patterns.

Main Results:

• Higher FAW larval density and infestation rates were observed in AEZ 8 compared to AEZ 6 during the dry season.
• During the rainy season, AEZ 8 showed a higher percentage of damaged plants, but larval density did not differ significantly between zones.
• FAW larvae exhibited moderate aggregation (index = 1.25) with an average initial cluster of 2.08 larvae per plant, suggesting oviposition behavior.

Conclusions:

• Agroecological zone and season significantly influence fall armyworm (FAW) population dynamics and distribution in Benin.
• The observed aggregation behavior of FAW is a key factor in its dispersion and requires consideration in IPM strategies.
• This research provides essential data for developing predictive models and optimizing pest control measures for FAW in maize.