Grasshopper (Orthoptera: Acrididae) damage to flowers and pods of lentil (Lens culinaris L.)

A study was initiated in response to concerns that grasshoppers were becoming an economic issue in lentil crops. The study characterized the type and extent of damage and determined the relationship between grasshopper numbers (Melanoplus bivittatus Say) in lentil (Lens culinaris L.) during flowering and yield loss. In commercial fields, grasshopper damage was found on sepals, flowers and both immature and mature pods. Grasshoppers at relatively low population density levels have a major impact on yield of lentil. Populations of 2-3/m(2) damaged up to 23 % of the viable pods and 47% of the flowers and immature pods. Field-cage trials along with recent estimates of crop yields, crop price and control costs were used to estimate an economic threshold. The relationship was linear (F = 42.98; P = 0.0001). The fitted linear relationship (y = 247.5 - 5.2x; R-2 = 0.71) estimates an average yield loss of approximately 2% for every one grasshopper/m(2). This information is pertinent to an economic evaluation of management strategies against grasshoppers in lentil. (C) 1999 Elsevier Science Ltd. All rights reserved.