Pheromone synthesis. Part 259: Synthesis of seven methyl-branched hydrocarbons as the pheromone candidates for female Korean apricot wasp, Eurytoma maslovskii

Recent advances in the synthesis of insect pheromones: an overview from 2013 to 2022

Covering: 2013 to June 2022Pheromones are usually produced by insects in sub-microgram amounts, which prevents the elucidation of their structures by nuclear magnetic resonance (NMR). Instead, a synthetic reference material is needed to confirm the structure of the natural compounds. In addition, the provision of synthetic pheromones enables large-scale field trials for the development of environmentally friendly pest management tools. Because of these potential applications in pest control, insect pheromones are attractive targets for the development of synthetic procedures and the synthesis of these intraspecific chemical messengers has been at the core of numerous research efforts in the field of pheromone chemistry. The present review is a quick reference guide for the syntheses of insect pheromones published from 2013 to mid-2022, listing the synthesized compounds and highlighting current methodologies in organic synthesis, such as carbon-carbon coupling reactions, organo-transition metal chemistry including ring-closing olefin metathesis, asymmetric epoxidations and dihydroxylations, and enzymatic reactions.

Asymmetric synthesis of the sex pheromone of the apple leafminer, Lyonetia prunifoliella

Lyonetia prunifoliella is a significant pest in orchards and damages apple. The sex pheromones of this pest were prepared via a new and concise method. The central to our method were Evans' chiral auxiliaries, the addition of chiral Grignard reagent to aldehyde and Wittig coupling.

Semiochemicals for intraspecific communication of the fig weevil Aclees sp. cf. foveatus (Coleoptera: Curculionidae): a first survey

The fig tree weevil Aclees sp. cf. foveatus (Coleoptera: Curculionidae), introduced in Italy in 2005, is currently causing significant economic and environmental losses to fig tree nurseries and orchards in Central Italy. Fig damages are due to the adults feeding on leaves and fruits, and to the galleries dug by the xylophagous larvae in the trunk, which lead the plants to death. To date, no chemical or biological control methods resulted to be effective against this invasive pest. In order to gain information about possible semiochemicals involved in mate recognition and choice, both the volatile organic compounds (VOCs) and the epicuticular lipids of male and female specimens were analysed. VOCs emissions of specimens were characterized essentially by monoterpenes, while epicuticular lipids contained long chained 2-ketones, alkanes, alkenes, including some methyl alkenes, and several fatty acid propyl esters. The attractiveness of reconstituted VOCs blends of the two sexes was tested in electrophysiological and behavioural assays in laboratory conditions. Both the male and the female reconstituted VOCs drove a significant response towards individuals of the opposite sex, thus demonstrating features of sexual attractants. Our results suggest a possible application of VOCs blends as pheromonic attractants in field monitoring and mass trapping of Aclees sp. cf. foveatus.

Tools in the Investigation of Volatile Semiochemicals on Insects: From Sampling to Statistical Analysis

The recognition of volatile organic compounds (VOCs) involved in insect interactions with plants or other organisms is essential for constructing a holistic comprehension of their role in ecology, from which the implementation of new strategies for pest and disease vector control as well as the systematic exploitation of pollinators and natural enemies can be developed. In the present paper, some of the general methods employed in this field are examined, focusing on their available technologies. An important part of the investigations conducted in this context begin with VOC collection directly from host organisms, using classical extraction methods, by the employment of adsorption materials used in solid-phase micro extraction (SPME) and direct-contact sorptive extraction (DCSE) and, subsequently, analysis through instrumental analysis techniques such as gas chromatography (GC), nuclear magnetic resonance (NMR) and mass spectrometry (MS), which provide crucial information for determining the chemical identity of volatile metabolites. Behavioral experiments, electroantennography (EAG), and biosensors are then carried out to define the semiochemicals with the best potential for performing relevant functions in ecological relationships. Chemical synthesis of biologically-active VOCs is alternatively performed to scale up the amount to be used in different purposes such as laboratory or field evaluations. Finally, the application of statistical analysis provides tools for drawing conclusions about the type of correlations existing between the diverse experimental variables and data matrices, thus generating models that simplify the interpretation of the biological roles of VOCs.

Design, synthesis and structure–activity relationships of mangostin analogs as cytotoxic agents

A series xanthone derivatives were synthesized and cytotoxicity results indicated that the isopentene group at C-8 is essential.