Ecology, behaviour and management of black harvester ant Solenopsis richteri (Forel) in Hamelmalo, Eritrea

The black seed harvester ant, Solenopsis richteri Forel (Hymenoptera; Formicidae), is one of the most serious pests of crops and grazing areas in the sub-zone Hamelmalo. A study on the harvester ant was conducted with the objectives of understanding its ecology, behaviour, and host types and assessing the damage caused by the pest. The ecology and behaviour assessments were done by observing the type and distribution of the nest, time of foraging, nest cleaning, and patrolling for foraging and mating. In addition, observations were made on the types of hosts and loss assessment using bio-pesticides and some selected insecticides on the bare area around the ant nest that was replicated in space. The outcome revealed that the ant constructs underground nests in open grassland and field crops that are devoid of trees and shrubs. The ant nests were distributed about 25 meters apart from each other, with a bare land area of 30-60m2 around their nest. The ants were actively foraging during the cold time of the day and during the night when the temperature was cool. The ants affect the crop at different stages by collecting the seeds during sowing and cutting the seedlings after germination and crop maturity. Its preferred hosts are grass seeds and crops, followed by small animals like termites, bugs, worms and seeds of some weed species. The harvester ants in the study area caused yield loss of 24-32Q per hectare and reduced the forage of the grazing areas for livestock.