Oviposition preferences of Plutella xylostella (L.) (Plutellidae: Lepidoptera) on water-stressed and non-stressed plants of Brassica napus L.

Abstract

Water stress influences the plant growth and quality, which in turn, alters the suitability of the host plant for insect herbivores. We investigated the suitability of four and six-week-old water-stressed host plants versus non-stressed plants in terms of oviposition preferences of the diamondback moth, Plutella xylostella (L.), on Brassica napus L. (Brassicaceae). Ovipositional preferences were significantly affected by the water treatment, plant age, and site for oviposition. Female moths preferred to oviposit on six-week-old, non-stressed plants of B. napus compared to the water-stressed counterparts. On average, 2.15 times more eggs were laid on non-stressed plants than the water-stressed ones. Similarly, 1.58 times more eggs were laid on host plant upper leaf surface than on the lower leaf surface. This study determined that P. xylostella females preferred to deposit eggs on six-week-old vigorous plants not under water stress to ensure the successful development and survival of their offspring.