Effect of multiple infestations from insect pests and other stresses to irrigated rice in the Philippines: II. Damage and yield loss

Abstract

Single and multiple species infestations of common insect pests were compared in terms of yield loss involving crop stresses that included weeds, sheath blight (Rhizoctonia solani Künh.), drought, and deficiencies of N and solar radiation in addition to insect pest infestations. Losses from the various combinations of stresses were found to be additive, antagonistic, or synergistic. Most combinations of insect pests produced additive losses, with the balance being antagonistic, so implying that compensation occurred. Combinations of insect damage with other biotic and abiotic stresses produced mostly synergistic crop losses, which were significantly greater than additive ones. Among insect pests, additive losses resulted from yellow stemborer (Scirpophaga incertulas [Walker]) attacking two rice growth stages while the same was true for leaffolder (Cnaphalocrocis medinalis [Guenée]). Only the combination of whorl maggot (Hydrellia philippina Ferino) and defoliators (a mixture of Naranga aenescens Moore and Rivula atimeta [Swinhoe]) produced synergistic losses. Knowing the mode of yield loss from combinations of different plant stresses will aid the farmer in making decisions regarding which ones should be corrected and which the crop can tolerate.

Keywords:

• rice insect pests
• yield loss
• multiple pest infestation
• drought stress
• nitrogen stress
• weeds
• sheath blight disease
• artificial pest infestation
• damage compensation
• green manure
• solar radiation