The timing of induced resistance and induced susceptibility in the soybean-Mexican bean beetle system

Abstract

Induced plant responses to herbivory have been demonstrated in many systems. It has been suggested that the timing of these responses may influence the impact of induced resistance on herbivore populations, and may affect the evolution of induced defenses. This study used a bioassay to characterize the time course of systemic induced responses to Mexican bean beetle herbivory in four genotypes of soybeans. The results suggest that the time course of induced responses in this system is more complex than most previous studies have indicated. Herbivory provoked both rapid induced resistance and subsequent induced susceptibility to beetle feeding. All four genotypes of soybean induced significant resistance to beetle damage (beetles preferred undamaged to damaged plants) by 3 days after damage. By 15 days after damage, this resistance had decayed (beetles showed no preference for undamaged over damaged plants), and by 20 days after damage, all four genotypes exhibited significant induced susceptibility (beetles preferred previously damaged plants over undamaged plants). The magnitude of induced resistance in each genotype correlated strongly with the magnitude of induced susceptibility in that genotype.

Increased Sulfur Precursors and Volatiles Production by the Leek Allium porrum in Response to Specialist Insect Attack

“…However, long-term protection is not consistently observed in all species. In tobacco, the concentration of nicotine returns to normal 14 d after induction (Baldwin, 1989), and induced resistance in Glycine max soybean disappears 20 d after the end of damage by Epilachna varivestis (Underwood, 1998). These findings could indicate that duration of the induced resistance may be correlated with the life cycle of the plant.…”

Invited Review - Fight on Plankton! or, Phytoplankton Shape and Size as Adaptive Tools to Get Ahead in the Struggle for Life

“…Although relaxation times should be as short as possible to minimise costs, literature on the relative timing of inducible defences suggests that quick induction and slow relaxation prevail in many organisms Schultz 1988;Hammerstrom et al 1998;Underwood 1998;Young & Okello 1998;Van Buskirk 2002;Stamp 2003), and irreversible defences (Boraas et al 1998;) may be the extreme case of this pattern. The time delays involved in induction and relaxation of defences may cause cyclic dynamics (e.g.…”

“…Thus, the timing of defence induction and relaxation are essential elements in the balance of costs and benefits of defences (e.g. Karban & Myers 1989;Adler & Harvell 1990;Hammerstrom et al 1998;Underwood 1998;Young & Okello 1998;Raimondi et al 2000;Zangerl 2003).…”

The evolutionary consequences of ecological interactions mediated through phenotypic plasticity

“…Although many examples of phenotypic plasticity exhibited in response to ecological interactions have been shown to be beneficial, such as induced resistance or defense, this is not always the case. For example, some herbivore-induced plant responses can increase a plant's susceptibility to further attack (Underwood, 1998). Thus, spatially and temporally separated herbivores can have indirect interactions with each other mediated through the phenotypically plastic responses of the plant.…”