The leaf-footed bug, Leptoglossus zonatus (Heteroptera: Coreidae), is mainly found in maize fields in Brazil. In this work, we elucidated and quantified the volatile compounds from nymphs and adults of L. zonatus. The defensive compounds produced by nymphs are aldehydes and oxo-alkenals, with some compounds showing different proportions between instars. For the first time, 5-ethyl-2(5H)-furanone has been identified as a defensive compound for a species of this family. In adults, the alarm pheromone includes hexanal, 1-hexanol, hexanoic acid, hexyl acetate, and octyl acetate. Males and females produce the same compounds, however, hexanal showed a significant difference between sexes. Gas chromatography (GC) analysis of adult aeration extracts revealed male specific compounds, which attactiveness to females was confirmed through olfactometer bioassays. By using a GC-electroantennographic detector (EAD), it was shown that female antenna presented electrophysiological responses to five components ((Z)-β-ocimene, (Z, Z)-allo-ocimene, decanal, α-trans-bergamotene, and (E)-β-farnesene) from male aeration extracts. In this way, we propose that males are responsible for emission of a sex pheromone in this species.

Comparative GC/MS analysis of airborne volatiles produced by males and females of the guava weevil Conotrachelus psidii (Coleoptera: Curculionidae: Molytinae) showed the presence of a malespecific electroantennographically active compound identified as (1R,2S,6R)-2-hydroxymethyl-2,6- dimethyl-3-oxabicyclo[4.2.0]octane (papayanol). Release of this compound was dependent on the photoperiod, taking place primarily during the scotophase, with a maximum release between 2 and 6 h after the onset of the scotophase. Y-tube olfactometer bioassays revealed a strong attractiveness of the papayanol to male and female weevils considering the presence of the plant volatiles.

O efeito de antioxidantes sintéticos, como BHT (butil-hidroxitolueno), BHA (butil-hidroxianisol) e TBHQ (t-butil-hidroxiquinona), foi avaliado sobre o período de indução de uma amostra de ésteres etílicos de óleo de soja de baixa estabilidade à oxidação, empregando o método Rancimat (EN14112). Efeitos de interação também foram investigados empregando-se um planejamento fatorial, que teve como níveis mínimos e máximos as concentrações de zero e 1500 ppm de cada antioxidante. Dentre os antioxidantes sintéticos avaliados, o BHT apresentou maior eficácia nas concentrações compreendidas entre 200 e 7000 ppm. O TBHQ apresentou maior potencial estabilizador quando utilizado em concentrações mais elevadas, enquanto que o BHA mostrou-se pouco efetivo nesta amostra, sendo que em concentrações superiores a 2000 ppm, não proporcionou qualquer acréscimo do período de indução. O uso combinado destes antioxidantes, nos níveis testados neste estudo, não evidenciou qualquer efeito sinérgico positivo que justifique o seu uso em misturas binárias ou ternárias.

The effect of synthetic antioxidants such as BHT (butyl-hydroxytoluene), BHA (butyl-hydroxyanisol) and TBHQ (t-butyl-hydroxyquinone) was evaluated on the induction time of soybean oil ethyl esters with low oxidation stability, employing the Rancimat method (EN14112). Interaction effects were also investigated by employing a 2³ factorial design, which had as minimum and maximum levels the concentrations of zero and 1500 ppm of each antioxidant. Among the synthetic antioxidants evaluated, BHT displayed the highest effectiveness in the concentration range from 200 to 7000 ppm. TBHQ displayed a greater stabilizing potential when used at higher concentrations (8000 ppm), while BHA was found to provide no noticeable increase in the induction time at concentrations greater than 2000 ppm. The combined use of these antioxidants, at the levels tested in this study, yielded no evidence of any positive synergic effect that would justify their use in binary or ternary mixtures.