Plant-mediated effects in the Brassicaceae on the performance and behaviour of parasitoids

Abstract

Direct and indirect plant defences are well studied, particularly in the Brassicaceae. Glucosinolates (GS) are secondary plant compounds characteristic in this plant family. They play an important role in defence against herbivores and pathogens. Insect herbivores that are specialists on brassicaceous plant species have evolved adaptations to excrete or detoxify GS. Other insect herbivores may even sequester GS and employ them as defence against their own antagonists, such as predators. Moreover, high levels of GS in the food plants of non-sequestering herbivores can negatively affect the growth and survival of their parasitoids. In addition to allelochemicals, plants produce volatile chemicals when damaged by herbivores. These herbivore induced plant volatiles (HIPV) have been demonstrated to play an important role in foraging behaviour of insect parasitoids. In addition, biosynthetic pathways involved in the production of HIPV are being unraveled using the model plant Arabidopsis thialiana. However, the majority of studies investigating the attractiveness of HIPV to parasitoids are based on experiments mainly using crop plant species in which defence traits may have changed through artificial selection. Field studies with both cultivated and wild crucifers, the latter in which defence traits are intact, are necessary to reveal the relative importance of direct and indirect plant defence strategies on parasitoid and plant fitness. Future research should also consider the potential conflict between direct and indirect plant defences when studying the evolution of plant defences against insect herbivory.

Defence mechanisms of Brassicaceae: implications for plant-insect interactions and potential for integrated pest management. A review

“…These chemical cues are important signals for orientation of both carnivorous enemies and herbivores, including distant host location by arthropods (Karban and Baldwin, 1997;Dicke, 1999;Dicke and Van Loon, 2000;Arab and Bento, 2006). Plants' responses upon damage caused by herbivores occurs through the regulation of several biochemical pathways that lead to the release of chemical compounds, which cause either repellence to herbivore insects or attraction to natural enemies (predators or parasitoids) of herbivore insects (Karban and Baldwin, 1997;Dicke and Van Loon, 2000;Pickett et al, 2003;Arab and Bento, 2006;Gols and Harvey, 2009). Attracted by herbivory-induced plant volatiles, parasitoids of herbivores perform host searching to lay their eggs in or on them as shown in recent studies (Mattiacci et al, 1994;Takabayashi and Dicke, 1996;Dicke, 1999;Hilker and Meiners, 2002;Fatouros et al, 2005b;Heil, 2008).…”

Parasitoids of Prodiplosis longifila Gagné (Diptera: Cecidomyiidae) and other Cecidomyiidae species in Colombia

“…For Brassicaceae species it was found that volatile emissions are very similar when plant are damaged by different herbivores and parasitoids cannot detect these differences (Gols & Harvey, 2009). For example our results show that S. aff.…”

Microbial Root Mutualists Affect the Predators and Pathogens of Herbivores above Ground: Mechanisms, Magnitudes, and Missing Links

“…For example, plant glucosinolates occurring within herbivore prey negatively affect a wide range of parasitoids (Gols and Harvey, 2009). While we focus here on root microbial mutualists, we note that there is now abundant evidence of root-feeding herbivores influencing the chemistry of plant tissues above ground, with subsequent effects on herbivore and enemy performance (Hunter, 2016).…”