Response of Soybean to Attack by Stemfly Melanagromyza sojae in Farmer's Fields in Indonesia

• Published in: The Journal of applied ecology 1998-08, Vol.35 (4), p.514-522
• Main Authors: Van Den Berg, H., Shepard, B. M., Nasikin
• Format: Article
• Language: English
• Subjects: Agroecology; Agromyzidae; Applied ecology; Biological and medical sciences; Crop ecology; Crops; Fundamental and applied biological sciences. Psychology; Glycine max; Hypocotyls; Infestation; Internodes; Melanagromyza sojae; pest damage; pesticides; Phytopathology. Animal pests. Plant and forest protection; Plant density; Plants; Protozoa. Invertebrates; Records, symptoms, damages, economic importance, population surveys; Soybeans; yield loss
• ISSN: 0021-8901; 1365-2664
• DOI: 10.1046/j.1365-2664.1998.3540514.x

1. To determine the effect of Melanagromyza sojae, a common pith-boring agromyzid fly, on soybean under field conditions in Indonesia, physiologically mature plants from 70 farmers' field sites were uprooted. Plant parameters and exit holes in the stem (created by M. sojae prior to pupation) were recorded. 2. Melanagromyza sojae was present at all sites and infested 84% of the plants. Farmers' applications of insecticides had no influence on the infestation level by M. sojae. Most exit holes occurred above the cotyledons. 3. Exit holes in the hypocotyl (i.e. the stem section below the cotyledons), indicative of early attack, were associated with a decrease in the number of seeds per plant, stem diameter and plant height. This suggests that early attack adversely affects plant development. Exit holes above the hypocotyl, indicative of attack later in the season, were associated with an increase in plant parameters, suggesting that late attack occurred in response to the plant's size or vigour. 4. Multiple regression was conducted to evaluate the influence of infestation on seed production. Separate models were used to analyse early and late attack. For late attack, the plant variables 'stem diameter' and 'plant height' were added to the regression. 5. Early attack caused less than 2% yield loss on a per-plant basis. Possible compensation by neighbouring plants was not considered. Later attack did not reduce yield. Therefore measures to control M. sojae would have been unwarranted. 6. Infestation had no effect on the 100-seed weight, confirming that the number of seeds per plant reliably predicted yield.