Plant Defense Chemicals against Insect Pests

Abstract

Insect pests cause significant global agricultural damage and lead to major financial and environmental costs. Crops contain intrinsic defenses to protect themselves from such pests, including a wide array of specialized secondary metabolite-based defense chemicals. These chemicals can be induced upon attack (phytoalexins) or are constitutive (phytoanticipins), and can have a direct impact on the pests or be used indirectly to attract their natural enemies. They form part of a global arms race between the crops and their insect pests, with the insects developing methods of suppression, avoidance, detoxification, or even capture of their hosts defensive chemicals. Harnessing and optimizing the chemical defense capabilities of crops has the potential to aid in the continuing struggle to enhance or improve agricultural pest management. Such strategies include breeding for the restoration of defense chemicals from ancestral varieties, or cross-species transfer of defense metabolite production.

Ecometabolomics of plant–herbivore and plant–fungi interactions: a synthesis study

“…This is also consistent with other studies reporting increased pantothenate concentrations as an inducible leaf defense against herbivore (von Dahl et al 2006, Rivas-Ubach et al 2016a. Moreover, triggering inducible defenses is energetically costly (Kant et al 2015, Yactayo-Chang et al 2020, which may explain why we found that mitochondrial electron transfer was additionally upregulated. An increase in the metabolism of inositol phosphate is also consistent with previous experimental studies, which have reported increases in concentrations of inositol pyrophosphates associated with induced defensive mechanisms triggered by jasmonate signaling under herbivore attack (Abreu and Aragao 2007, Shah et al 2017, Freed et al 2020, Lorenzo-Orts et al 2020).…”

The Brown Marmorated Stink Bug (Halyomorpha halys Stål.) Influences Pungent and Non-Pungent Capsicum Cultivars’ Pre- and Post-Harvest Quality

“…Flavones are known to be defense molecules, as previously noted by Soriano, Asenstorfer, Schmidt, and Riley [23], who reported an increased synthesis of flavones as a response to an invasion by parasitic nematodes in oats (Avena sativa). High levels of flavones are also present in silks of maize (Zea mays), which increase the resistance to corn earworm [45]. Flavonoids can deter or attract insects.…”

Offspring performance and female preference of Pagiophloeus tsushimanus (coleoptera: curculionidae) on three Lauraceae tree species: A potential risk of host shift caused by larval experience

“…Since semi‐artificial diets made from plant branches were used as food resources for larvae, the explanation that structural defences such as thorns and waxy cuticles of branches form a physical barrier that prevents the growth and development of larvae can be excluded. Another possible reason is that novel hosts have a variety of plant defence chemicals (secondary metabolites), which are directly toxic to certain herbivorous insects (Yactayo‐Chang et al., 2020). According to the available literature, there are significant differences in the main secondary metabolites of the Lauraceae tree species that we tested (Table S3) (Chen et al., 2019; Jiang et al., 2016; Yang et al., 2009).…”