Field and Laboratory Evaluation of Trunk Injection with Three Insecticides for Controlling the Palm Stem Borer Oryctes elegans Prell in Babylon Province, Iraq

The palm stem borer, Oryctes elegans. Pell, is considered one of the most destructive pests attacking date palm trunks in the middle Euphrates region. In Babylon governorate, many old orchards suffer from severe infestation, which often leads farmers to cut the trees. During 2024-2025, we conducted both laboratory and field trials at Al-Mussaib Technical College and in three private orchards in Babylon. In the laboratory, 90 last instar larvae were tested (10 larvae for each replicate, three replicates per insecticide). In the field, we used 72 palm trees distributed in three orchards following Randomized Complete Block Design. Each orchard contained 24 palms: 9 for trunk injection, 9 for conventional spraying, and 6 as untreated control. For injection, we drilled a hole of about 0.5 cm diameter and 12 cm depth at a 45-degree angle, at 1.5 m height, injected 1 liter solution per palm and closed the hole with wax. Three insecticides were evaluated: Carbaryl (20 g/L), Fipronil (2 ml/L), and Chlorpyrifos 48% (3 ml/L). After 24 hours in lab, mortality was 79.0% for Carbaryl, 74.26% for Fipronil, and 63.26% for Chlorpyrifos. Statistical analysis showed significant differences (F = 14.51, p = 0.0050, LSD0.05 = 7.33). After five days, mortality increased to 85.66%, 78.43%, and 72.63% respectively (F = 8.60, p = 0.0172, LSD0.05 = 7.70). Under field conditions, light trap catches decreased from 13 to 0 insects/trap for Carbaryl (100% reduction) and from 15 to 0 for Fipronil (100%), while Chlorpyrifos decreased from 14 to 2 (85.7%). These results indicate that trunk injection, particularly with Carbaryl, can achieve complete control after three months and could be recommended for Babylon orchards.