Damage to coconut palms by Azteca sp. (Hymenoptera: Formicidae) and insecticidal control with bait, in Guyana.
A general survey of coconut plantations in Guyana in 1976 indicated that in the total area of about 18 700 ha, 1000 of the 3000 ha of coconut palms on the east coast of Demerara were infested by Azteca sp. Detailed crop loss assessments on four plantations in 1970-72 indicated that the overall loss of crop to this pest in Guyana in 1976 was about 3.7 million coconuts, valued at G$372 000. Damage is partly due to colonies of Nipaecoccus nipae (Mask) and Aspidiotus destructor Sign. maintained by the ants and may also be partly attributed to interference with pollinating insects. Chemical control with aldrin and dieldrin sprays applied to tree trunks to create insecticide barriers and applied to whole trees with a power sprayer and extension lance did not give adequate long-term control. Baits based on minced bovine intestine with 2% v/w ethyl alcohol were therefore assessed in field trials. Aldrin at 0.3-2.4%, nonachlor [1,2,3,4,5,6,7,8,8-nonachloro-2,3,3a,4,7,7a-hexahydro-4,7-methano-1H-indene] at 0.3-2.0% and mirex at 0.05-0.6% were tested. Bait containing 0.1% mirex gave best results with complete kill of ants' nests 60 days after application at about 5 kg bait/ha. Mealybug and scale infestations were also eliminated by this treatment, with subsequent reductions in leaf-yellowing and increases in leaf number 100 days after treatment. Up to September 1976, 0.15% mirex bait had been used to control Azteca sp. on 200 ha of coconut palms in Guyana.