Effect of fear and host quality on oviposition and larval behaviour of Plutella xylostella (Lepidoptera: Plutellidae)

The presence of predators can induce non-consumptive effects on prey and influence prey behaviour and defense. Such effects can reduce prey fitness, and in combination with direct predation, can negatively affect pest population and performance. While direct consumptive effects of generalist predators of the diamondback moth Plutella xylostella L. are documented, not much is known about the non-consumptive effects of most predators. We tested the effect of the presence of different predator life stages (larvae or adults) on P. xylostella oviposition, larval survival, growth and leaf consumption. There was no effect of the presence of Coccinella septumpunctata adults or its interaction with plant fertilization regime on oviposition of P. xylostella. Host plant nutrition impacted oviposition choice. The P. xylostella females laid ~ 2 times more eggs on the plants that received high fertilization rates compared to plants with low fertilization. Perception of adult C. septumpunctata presence reduced overall leaf consumption of P. xylostella by 24%. The mere presence of C. septumpunctata larvae, reduced larval P. xylostella weight by 19% compared to control larvae that were not exposed to predators. Weight loss was the result of less feeding, as predator presence reduced the leaf area consumed by P. xylostella larvae by ~35%. These results confirm that non-consumptive effects and consumptive effects together can negatively affect fitness gains in P. xylostella larvae. Future studies on DBM natural enemy guilds should focus on the collective influence of consumptive and non-consumptive effects on P. xylostella fitness gains and interaction dynamics.