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The red mite, Oligonychus yothersi (McGregor) (Acari: Tetranychidae), is a serious foliar pest of avocado (Persea americana Mill.) orchards in Chile. In summer, avocado plants release herbivore-induced plant volatiles (HIPVs) in response to feeding behaviour of O. yothersi. These HIPVs recruit natural enemies of the red mite as Parastethorus histrio (Chazeau) (Coleoptera: Coccinellidae) and Oligota pygmaea (Solier) (Coleoptera: Staphylinidae). However, P. histrio and O. pygmaea remain in infested avocado trees throughout the summer until late autumn. Therefore, we collected HIPVs, in late autumn, to test the behavioural responses of the red mite and its coleopterans predators. Volatiles were collected under semi-field conditions using the headspace technique and Porapak Q as adsorbent. The chemical analysis revealed that infested plants emitted (Z)-β-ocimene, α-farnesene, and methyl salicylate (MeSA), increasing the emissions of R-limonene. These variations triggered an attractive behaviour in P. histrio and O. pygmaea, yet O. yothersi remained indifferent. The emitted HIPVs by avocado infested plants, in late autumn, elicited tri-trophic interactions in avocado orchards, where higher R-limonene emissions and up-regulated three new volatile compounds in the volatiles profile could have influenced predator's choice, being necessary to examine. [ABSTRACT FROM AUTHOR]

In response to herbivory by cabbage white butterfly (Pieris rapae) larvae, crucifer plants emit green leaf volatiles (GLVs) that attractCotesia glomerata, a carnivorous natural enemy of the larvae. To artificially increase GLV production by crucifers, we created transgenicArabidopsisthat constitutively expressed cucumber cytosolic lipoxygenase (CsLOX2). TransgenicArabidopsis(p35S::CsLOX2.6andp35S::CsLOX2.14) infested withP. rapaelarvae were more attractive toC. glomeratathan wild type (wt) and produced more jasmonic acid.p35S::CsLOX2.14had a higher incidence of parasitism of the larvae than did wt. Infested transgenic plants emitted more (Z)-3-hexenyl acetate, (E)-β-ocimene, (Z)-β-ocimene, and DMNT than infested wt plants; (Z)-3-hexenyl acetate is known to attractCotesiawasps. Transforming cruciferous crops with cytosolicCsLOX2could aid integrated pest management via tritrophic interactions. [ABSTRACT FROM PUBLISHER]

Plants show a diversity of defense strategies against a wide range of herbivores. The emission of a specific blend of volatiles in response to herbivory (HIPVs - herbivore-induced plant volatiles) plays a great ecological role in indirect protection of the plants by attracting natural enemies of herbivores and priming their neighboring plants that can cause poorer foraging habitats on the 'receiver' plants. Maize plants showed induction of a blend of volatiles including monoterpenes, sesequiterpenes, homoterpenes, green leaf volatiles, and indole, in response to the specialist herbivore Mythimna separata. Conspecific plants placed downwind of infested maize plants showed reduced larval development after exposure to HIPVs, compared to those exposed to volatiles from uninfested plants. These findings indicate that exposure of maize plants to HIPVs primed these plants for enhanced defense responses to specialist herbivores of Poaceae. [ABSTRACT FROM AUTHOR]