Herbivore-induced maize leaf volatiles affect attraction and feeding behavior of Spodoptera littoralis caterpillars

Abstract

Plants under herbivore attack emit volatile organic compounds (VOCs) that can serve as foraging cues for natural enemies. Adult females of Lepidoptera, when foraging for host plants to deposit eggs, are commonly repelled by herbivore-induced VOCs, probably to avoid competition and natural enemies. Their larval stages, on the other hand, have been shown to be attracted to inducible VOCs. We speculate that this contradicting behavior of lepidopteran larvae is due to a need to quickly find a new suitable host plant if they have fallen to the ground. However, once they are on a plant they might avoid the sites with fresh damage to limit competition and risk of cannibalism by conspecifics, as well as exposure to natural enemies. To test this we studied the effect of herbivore-induced VOCs on the attraction of larvae of the moth Spodoptera littoralis and on their feeding behavior. The experiments further considered the importance of previous feeding experience on the responses of the larvae. It was confirmed that herbivore-induced VOCs emitted by maize plants are attractive to the larvae, but exposure to the volatiles decreased the growth rate of caterpillars at early developmental stages. Larvae that had fed on maize previously were more attracted by VOCs of induced maize than larvae that had fed on artificial diet. At relatively high concentrations synthetic green leaf volatiles, indicative of fresh damage, also negatively affected the growth rate of caterpillars, but not at low concentrations. In all cases, feeding by the later stages of the larvae was not affected by the VOCs. The results are discussed in the context of larval foraging behavior under natural conditions, where there may be a trade-off between using available host plant signals and avoiding competitors and natural enemies.

Antixenosis of bean genotypes to Chrysodeixis includens (Lepidoptera: Noctuidae)

“…For instance, 'Flor de Mayo' was lightly attractive (Figure 2), but revealed a high consumption index. This suggests that the biggest attraction of the insect by the host plant does not necessarily reveal to be the appropriate food for larval development (Von Mérey et al, 2013). As reported Table 2.…”

Herbivore intoxication as a potential primary function of an inducible volatile plant signal

“…; von Mérey et al . ). Plants themselves can perceive HIPVs and employ them to pre‐activate their defences (Engelberth et al .…”

Tomato treatment with chemical inducers reduces the performance of Spodoptera littoralis (Lepidoptera: Noctuidae)

“…Herbivore caterpillars may perceive such enhanced HIPVs as signals of either a greater risk of cannibalism from conspecifics or a greater risk of predation from natural enemies (Bruce and Pickett 2011). Subsequently, exposure to emitted HIPVs decreases the growth rates of the feeding herbivores (von Mérey et al 2013;Yoneya et al 2014). Supporting such an hypothesis, Uefune et al (2013) found that the oviposition of Tetranychus urticae C.L.…”