Volatile Organic Compounds from Cassava Plants Confer Resistance to the Whitefly Aleurothrixus aepim (Goeldi, 1886)

Cassava is an essential tuber crop used to produce food, feed, and beverages. Whitefly pests, including Aleurothrixus aepim (Goeldi, 1886) (Hemiptera: Aleyrodidae), significantly affect cassava-based agroecosystems. Plant odours have been described as potential pest management tools, and the cassava clone M Ecuador 72 has been used by breeders as an essential source of resistance. In this study, we analysed and compared the volatile compounds released by this resistant clone and a susceptible genotype, BRS Jari. Constitutive odours were collected from young plants and analysed using gas chromatography-mass spectrometry combined with chemometric tools. The resistant genotype released numerous compounds with previously described biological activity and substantial amounts of the monoterpene (E)-β-ocimene. Whiteflies showed non-preferential behaviour when exposed to volatiles from the resistant genotype but not the susceptible genotype. Furthermore, pure ocimene caused non-preferential behaviour in whiteflies, indicating a role for this compound in repellence. This report provides an example of the intraspecific variation in odour emissions from cassava plants alongside information on odorants that repel whiteflies; these data can be used to devise whitefly management strategies. A better understanding of the genetic variability in cassava odour constituents and emissions under field conditions may accelerate the development of more resistant cassava varieties.

Molecular docking studies and evaluation of the antiretroviral activity and cytotoxicity of the species Lafoensia pacari Saint-Hilaire

Interest in antiviral plant species has grown exponentially and some have been reported to have anti-HIV properties. This research aims to perform the bio-guided phytochemical fractionation by antiretroviral activity of Lafoensia pacari stem barks. This in vitro experimental study involved the preparation of plant material, obtention of ethanolic extract, fractionation, purification, identification and quantification of fractions, acid-base extraction, nuclear magnetic resonance, HIV-1 RT inhibition test and molecular docking studies. From the bio-guided fractionation by the antiretroviral activity there was a higher activity in the acetanolic subfractions, highlighting the acetate subfraction - neutrals with 60.98% of RT inhibition and ellagic acid with 88.61% of RT inhibition and absence of cytotoxicity. The macrophage lineage cytotoxicity assay showed that the chloroform fraction was more toxic than the acetate fraction. The analysis of the J-resolved spectrum in the aromatic region showed a singlet at 7.48 and 6.93 ppm which was identified as ellagic acid and gallic acid, respectively. The 5TIQ enzyme obtained better affinity parameter with the ellagic acid ligand, which was confirmed by the HSQC-1H-13C spectra. Gallic acid was also favorable to form interaction with the 5TIQ enzyme, being confirmed through the HSQC-1H-13C spectrum. From the PreADMET evaluation it was found that ellagic acid is a promising molecule for its RT inhibition activity and pharmacokinetic and toxicity parameters.

Sexual Behavior of the Sugarcane Hairy Borer, Hyponeuma taltula (Lepidoptera: Erebidae): Evidence for a Female-Released Sex Pheromone

The sugarcane hairy borer, Hyponeuma taltula (Schaus, 1904), attacks the base of sugarcane and causes the death of the apical bud, a symptom known as "dead heart." In recent years, there has been significant infestation in Brazilian sugarcane crops. With the purpose of finding methods for controlling and/or monitoring the pest for the sustainable cultivation of sugarcane, we characterized the mating behavior of H. taltula and confirmed the release of a sex pheromone by this insect. Sexual activity was observed between the second and ninth hour of scotophase, during which female calling caused the onset of male courtship behaviors and increased their frequency. An ethogram was built showing that males perform seven observable steps: (1) wing flapping, (2) walking with wing flapping, (3) flying, (4) flying towards the female, (5) landing near the female and walking around her, (6) attempting copulation, and (7) copulation (mating). Female sex gland extracts also triggered attraction and male courtship behaviors. These results thus confirm that the female abdominal gland produces a sex pheromone and that the presence of this pheromone in the air is needed to initiate the male courtship sequence. The sexual behavior of H. taltula is compatible with control and/or monitoring methods using female sex pheromones.

Identification of stable fly attractant compounds in vinasse, a byproduct of sugarcane-ethanol distillation

The stable fly, Stomoxys calcitrans (Diptera: Muscidae), is a worldwide pest of livestock. Recent outbreaks of stable flies in sugarcane fields in Brazil have become a serious problem for livestock producers. Larvae and pupae found inside sugarcane stems after harvesting may indicate that stable flies use these stems as potential oviposition or larval development sites. Field observations suggest that outbreaks of stable flies are associated with the vinasse and filter cake derived from biomass distillation in sugarcane ethanol production that are used as fertilizers in sugarcane fields. Adult stable flies are attracted to vinasse, which appears to present an ideal larval development site. The primary goal of the present study is to demonstrate the role of vinasse in influencing the sensory physiological and behavioural responses of stable flies, and to identify its associated volatile attractant compounds. Both laboratory and field studies showed that vinasse is extremely attractive to adult stable flies. Chemical analyses of volatiles collected revealed a wide range of carboxylic acids, alcohols, phenols and aldehydes as potential attractant compounds. These newly identified attractants could be used to develop a tool for the attractant-baited mass trapping of stable flies in order to reduce infestations.