Plants can detect herbivore‐induced plant volatiles (HIPVs) from their damaged neighbours and respond by enhancing or priming their defenses against future herbivore attack. Plant communication and defense priming by volatile cues has been well documented, however, the extent to which plants are able to perceive and respond to these cues across different environmental contexts remains poorly understood. We investigated how abiotic changes that modulate stomatal conductance and/or defense signalling affect the ability of maize plants to perceive HIPVs and respond by priming their defenses. During light exposure, when stomata were open and conditions allowed for defense signal biosynthesis, the individual compounds indole and (Z)−3‐hexenyl acetate primed maize defenses. Neither compound primed defenses under environmental conditions that closed stomata and/or altered defense signalling. Moreover, plants were not primed when exposed to indole or (Z)−3‐hexenyl acetate in darkness (while stomata were closed) and then subjected to simulated herbivory in the light, to ensure defense induction. The full blend of HIPVs primed maize defenses in light conditions but suppressed defense induction during dark exposure and wounding. These findings indicate that environmental context is important for plant communication and defense priming and suggest that stomata play a role in plant perception of HIPVs.

Insect pests such as Spodoptera frugiperda cause significant losses to maize (Zea mays mays). Control of S. frugiperda is difficult, but the use of insect resistant cultivars, including tolerant cultivars, is a promising alternative, and landraces are a potential source of insect resistance. This study investigated tolerance to S. frugiperda in five Brazilian landraces, Amarelão, Aztequinha, Branco Antigo, Palha Roxa, and São Pedro, in relation to one conventional (non-Bt) hybrid, BM207, under field conditions. We assessed tolerance as the ratio of insecticide-free to insecticide-protected plants for plant height, stem diameter, and leaf chlorophyll content at two plant stages. Tolerance ratios varied across the maize genotypes, but inconsistently across plant variables, and cluster analysis revealed three groups based on tolerance ratios. A first group contained genotypes similarly tolerant to S. frugiperda, BM207, Palha Roxa, São Pedro, and Aztequinha, while the second and third groups each contained single genotypes, Amarelão, and Branco Antigo, which were considered not tolerant. Overall, the landraces Palha Roxa, São Pedro, and Aztequinha compared favorably to BM207 in terms of tolerance, and therefore may be valuable for management of this pest, and as germplasm sources to improve tolerance in other cultivars.

Spodoptera frugiperda is a pest of worldwide importance, responsible for significant economic losses, mainly in maize crops. The use of botanical derivatives emerges as a promising alternative to control this insect pest. In this work, we evaluated the effect of ethanolic extracts (EE) and semi-purified fractions of Acnistus arborescens and Datura stramonium (Solanaceae) on the biological development of S. frugiperda and the effects of the semi-purified fractions on feeding behavior of 4th instar caterpillars. Crude extracts and fractions caused lethal and sublethal effects, namely increasing both duration of larval and pupal stages as well as deformities in adults, and decreasing weight of pupae. In turn, the effects on feeding deterrence were more pronounced in treatments with A. arborescens fractions. Our results highlight the potential of EE from solanaceous species as a source of allelochemicals that can be used in the integrated management of S. frugiperda.

The Tuta absoluta species represents a significant threat to solanaceous crops globally and has developed resistance to conventional synthetic insecticides. This study investigated the insecticidal properties of essential oils (EOs) from Melaleuca alternifolia and Eucalyptus staigeriana against T. absoluta using the age-stage, two-sex life table methodology. Initially, the EOs of M. alternifolia and E. staigeriana were chemically characterized by gas chromatography (GC) techniques. In this analysis, we identified 19 compounds in M. alternifolia essential oil, with terpinen-4-ol, γ-terpinene, and α-terpinene as the predominant constituents. Eucalyptus staigeriana essential oil contained 25 identified compounds, predominantly limonene, terpinolene, geranial, and neral. Essential oils were dissolved in acetone and applied topically to larval stages. Both treatments significantly reduced pest longevity and adversely affected key demographic parameters. Melaleuca alternifolia treatment resulted in a substantial decrease in the intrinsic rate of population increase, indicating potential for population suppression. These findings support the potential application of M. alternifolia and E. staigeriana EOs as biological control agents against T. absoluta in integrated pest management programs.

The tomato leafminer Phthorimaea absoluta is an important pest of solanaceous plants and is considered a key pest of tomato plants. This pest is rapidly dispersed, difficult to con-trol, and resistant to the main synthetic insecticides. The objective was to determine the lethal and sublethal effects of three essential oils (Eos) of Melaleuca alternifolia and Euca-lyptus staigeriana against P. absoluta. We evaluated the effects of the EOs during the life cy-cle of the pest using an age-stage, two-sex life table. The treatments were solubilized in ac-etone and applied to the back of the caterpillars. The EOs of M. alternifolia and E. staigeriana reduced P. absoluta longevity to 22.2 and 15.9 days and negatively impacted demographic parameters. Melaleuca alternifolia notably decreased the intrinsic rate of increase. Chroma-tographic findings revealed the presence of 19 compounds in the M. alternifolia EO, with terpinen-4-ol, γ-terpinene and α-terpinene being the most abundant. On the other hand, E. staigeriana presented 25 constituents, with the compounds limonene, geranial and neral being the most abundant. The results obtained demonstrate the insecticidal potential of M. alternifolia and E. staigeriana EOs in the control of P. absoluta.