Table 1.

External application of phytohormones in inducing plant defense to herbivores.

Type of Insect	Plant Species	Induced Defense	Protective Function	Reference
Effect of JA and Its Derivatives
Helicoverpa armigera	Arachis hypogaea	Increased activity of POD, PPO and total phenol, H2O2 and MDA	Host plant defense to herbivore	[87]
Pieris rapae and Plutella xylostella	Brassica oleracea	Emission of volatile compounds, such as β-ocimene, thuja 2,4(10)-diene, and terpinene	Attraction of parasitoids, such as Cotesia glomerata, C. rubecula, and Diadegma semiclausum	[88]
Nilaparvata lugens	Rice	Emission of plant volatiles, i.e., aliphatic aldehydes, alcohols, monoterpenes, sesquiterpenes, methyl salicylate, etc.	Attracts Anagrus nilaparvatae (egg parasitoid)	[89]
Diatraea saccharalis	Sugarcane	Emission of blend of sesquiterpenes	Attracts parasitoid Cotesia flavipes	[90]
Plutella xylostella	Brassica napus	Production of glucosinolates and trypsin inhibitor	Reduced survivorship of Plutella xylostella	[91]
Spider mites	Lima bean (Phaseolus lunatus)	Transcript levels of (E)-β-ocimene synthase (PlOS) increased and increased emission of (E)-β-ocimene	Enhanced biological control of spider mites due to increased volatiles emission	[92]
Effect of SA and Its Derivatives
Frankliniella occidentalis	Jacobaea. aquatica	Increased levels of threonine, citric acid, and alanine	Reduced thrips population and inhibited feeding	[93]
Oebalus pugnax	Rice, Oryza sativa	Increased plant volatiles production	Reduced damage by stinkbug and prevented formation of spikelet sterility	[94]
Aphids/mites	Washington hop yard	Indirect defense	More attraction of Chrysopa nigricornis	[95]
Bactrocera dorsalis	Mango	Increased levels of anti-oxidative enzymes, such as catalase, peroxidase, poly phenoloxidase, along with phenol and flavonoid	Reduced oviposition, larval and adult emergence of Bactrocera dorsalis	[96]
Helicoverpa armigera	Ground nut	Increased glutathione s-transferase activity	Reduction in larval weight and survival	[87]
Psyllid, Agonoscena pistaciae	Pistachio	High phenol and H2O2production	Reduced survival of A. pistaciae	[97]
Psyllid, Agonoscena pistaciae	Pistacia vera	Increased production of anti-oxidative enzymes, such as polypheloxidase, and peroxidase	Reduction in the number of eggs and in nymphal density	[98]
Effect of Gibberellic Acid(GA)
Spodoptera frugiperda	Maize	Increased silicon uptake in plants	Decreased fecundity and reduced feeding on corn in S. frugiperda	[99]
Pea aphid, Acyrthosiphon pisum	Medicago truncatula	Increased levels of JA and SA and JA-related plant gene expression	Decreased fitness of A. pisum	[100]

POD: peroxidase; PPO: polyphenol oxidase; H₂O₂: hydrogen peroxide; MDA: malondialdehyde.