Trade-offs between constitutive and induced resistance in wild crucifers shown by a natural, but not an artificial, elicitor

Abstract

Constitutive and induced plant resistance against herbivores occurs throughout the plant kingdom, but little is known about the evolutionary relationship between these two types of resistances. We examined the relationships between constitutive and induced resistance to the diamondback moth, Plutella xylostella, in 11 wild species of crucifers, and analyzed the changes in volatiles associated with their expression in two species. We used larvae of P. xylostella and jasmonic acid (JA) as elicitors of the induced response. The level of resistance was estimated as the relative number of eggs laid on the plants by P. xylostella. Substantial variation in constitutive resistance was observed among the 11 crucifer species. When the plants were damaged by larvae, a negative correlation was found between constitutive and induced resistance. However, a positive correlation was detected between constitutive and induced resistance when the plants were treated by JA. The shift in resistance was associated with changes in the emission of volatiles. These results strongly suggest that (1) a trade-off occurs between constitutive and induced resistance in wild crucifers, and that (2) such a trade-off can be observed by treating the plants with a natural, but not an artificial, elicitor.

Relationship between adult oviposition preference and larval performance of the diamondback moth, Plutella xylostella

“…For cultivated hosts induction by P. xylostella infestation can lead to an increase in egg laying on B. oleracea and a decrease on B. campestris (Lu et al 2004b). Similarly for some weed hosts induction by P. xylostella infestation results in an increase in egg laying on C. impatiens, L. virginicum, and C. bursa-pastoris, and a decrease on R. indica, C. limprichtiana, and C. hirsute (Zhang et al 2008). Moreover, larval performance was not consistent with adult preference among these weed hosts.…”

“…These results indicate that, once host plants are pre-infested by conspecific larvae, female P. xylostella seems less able to select a better host for its offspring. This could partly be due to the changes in secondary metabolisms of host plant in response to herbivory (Zhang et al 2008). However, performance on these hosts needs to include the responses of the third trophic level, as natural enemies may cue on host damage (Zhang et al 2009).…”

“…d)], where c and d are the mean number of eggs laid on Chinese cabbage (Brassica campestris L. ssp. pekinensis) and on any other given crucifer in two-choice test (Zhang et al 2008). Thus, OPI ranges from 0 (when no eggs are laid on the other host) to 1 (when equal numbers of eggs are laid on the two hosts) and then to 2 (when all eggs are laid on the other host).…”

“…We searched the literature for data on P. xylostella life history traits that could be used to explore the relationship between adult oviposition preference and offspring performance (Fox and Eisenbach 1992;Muhamad et al 1994;Lu et al 2004b;Safraz et al 2007;Zhang et al 2008;Zhang et al 2009). Intrinsic rate of increase, pupal weight, and fecundity of the ensuing adults were regarded as an indicator of larval performance of P. xylostella on any particular host substrate.…”

“…Although the oviposition preference (Zhang et al 2008;Zhang et al 2009;Fathi et al 2011) and performance (Safraz et al 2007;Golizadeh et al 2009;Staley et al 2009;Soufbaf et al 2010a, b) of P. xylostella on various cultivated and wild crucifers have been examined, the relationship between adult preference and offspring performance has not been explicitly considered. In this study, we re-analyze previously reported data on the performance of P. xylostella on different cultivated and wild crucifers, as well as adult oviposition preference.…”