Exposure to polyphenol-rich purple corn pericarp extract restricts fall armyworm(Spodoptera frugiperda)growth

Abstract

Bioactive compounds such as polyphenols in plants have been well studied for their potential insecticidal activities. These are considered as safe alternatives against chemical pesticides because of their lower persistence in environment, lower toxicity to humans and other organisms. However, they are present constitutively in lower amounts in plants and have to undergo complicated extraction methodshampering their commercial exploitation in pest management. Using an inexpensive extraction method developed to recover polyphenol-rich liquid extract from purple corn pericarp, we recently documented that this extract has anti-feeding effects that cascade from larval to adult stages in a model herbivore tobacco hornworm (Manduca sexta). However, M. sexta does not feed on corn or any other major crops other than the species in the nightshade family (Solanaceae). In this study, we explored the same idea but using a generalist and common herbivore on corn, the fall armyworm (Spodoptera frugiperda). We found that purple corn pericarp extract inhibited the larval growth and development as well as negatively affected the pupal stages of S. frugiperda. However, unlike on M. sexta, time to complete larval life cycle was unaffected. Our findings confirm the toxicity of this extract on a generalist, economically important herbivore, but also suggest potential species-specific effects that should be explored further.

The Multifunctional Roles of Polyphenols in Plant-Herbivore Interactions

“…Re-focusing to extract such compounds by developing inexpensive, simple, environmental and farmer friendly methods to combat the losses incurred due to biotic stressors. Recently, polyphenol rich pericarp extract, a byproduct of corn processing industry, extracted by inexpensive techniques has been found to negatively affect the growth and development of specialist insect herbivore M. sexta [8,23] (Table 1) as well as against generalist herbivore fall armyworm (S. frugiperda) [9] (Table 1). Such waste byproducts of food industry and other waste plant sources should be further explored under different systems and herbivores with different feeding behavior.…”

“…However, selection pressure for survival in this never ending co-evolutionary arms race has also led to the development of complex, biochemically based, and tightly regulated second line of defenses. These include the production of toxins that deter herbivores from feeding, reduce the palatability/digestibility of plant tissue, and compounds that can negatively affect herbivore growth and development [8,9]. These defenses also include the release of constitutive and herbivore induced plant volatiles that attract predators and parasitoids, Int.…”

Cascading Effects of Cover Crops on the Subsequent Cash Crop Defense against the Polyphagous Herbivore Fall Armyworm (Spodoptera frugiperda)

“…The eggs were allowed to hatch at room temperature, after which they were transferred to petri dishes with artificial diets. For more details about FAW rearing, please see [ 24 ].…”

“…S. frugiperda caterpillars were allowed to feed on a wheat germ-based artificial diet, which was prepared based on the recommendations of the commercial vendor (Frontier Agricultural Sciences): 100 mL of water was boiled to 85 °C followed by adding 250 g of the artificial diet, which was then thoroughly mixed until there were no more lumps. For detailed information about the preparation of artificial diets, see [ 24 , 25 ].…”

Are epicuticular waxes a surface defense comparable to trichomes? A test using two Solanum species and a specialist herbivore

“…It is well-established that plants use both physical and chemical defenses to protect themselves against arthropod herbivores (Singh and Kariyat, 2020;Tayal et al, 2020a;Singh et al, 2021). Physical defenses mainly include waxes, trichomes and spines.…”