Initial field trials with the synthetic sex pheromone of the processionary mothThaumetopoea pityocampa (Denis and Schiff.)

Recent Advances in Management by Pheromones of Thaumetopoea Moths in Urban Parks and Woodland Recreational Areas

Caterpillars of the pine processionary moths, Thaumetopoea complex, cause serious defoliation to Cedrus, Pinus, and Pseudotsuga trees. Thaumetopoea caterpillars also have fine hairs on their abdominal tergites that contain a protein that can severely irritate and cause dermatitis in humans and domestic animals. The control of the T. pityocampa pine processionary moth has become necessary in many European countries because of the sanitary risks that are related to larval urtication and the defoliation threat to pine forests and plantations. New research activities have been aimed at the development of eco-friendly, innovative technologies for Integrated Pest Management (IPM) of these moths, particularly in urban parks and woodland recreational areas. This paper describes the recent advances in the use of pheromones in monitoring, mass trapping, and mating disruption related to management of processionary moths T. hellenica and T. pityocampa. According to the results, the use of pheromones may provide a practical alternative to insecticide sprays, as they can be safe and simple as compared to other control methods.

Analogs of sex pheromone of processionary moth,Thaumetopoea pityocampa: Synthesis and biological activity

The synthesis and biological activity of some analogs of (Z)-13-hexadecen-11-ynyl acetate1, the major component of the sex pheromone of the processionary mothThaumetopoea pityocampa is described. The analogs have been formally derived by structural modification of the enyne and acetate functions of the parent compound1. In field tests, trifluoroacetate ester16 and the analog,11, with fluorine substitution at the olefin site, decreased the pheromone action, whereas epoxy derivative,10, from epoxidation of the olefin moiety in1, and propionate ester15 gave synergistic activity. The formate14 had a variable effect according to the composition of the lure. Formal reduction of the enyne to give the acetylene2 was found to retain activity. Alcohols12 and13, resulting from hydrolysis of the enyne1 and acetylene2, respectively, inhibited the action of their parent compounds.

Behavior of processionary males (Thaumetopoea pityocampa) induced by sex pheromone and analogs in a wind tunnel

The behavioral response of processionary males (Thaumetopoea pityocampa) to the natural pheromone (Z)-13-hexadecen-11-ynyl acetate (1) and structurally related analogs in a wind tunnel is presented. Stereomerically pureZ-1 and a mixture with theE isomer in 80:20 ratio elicited similar attraction responses at 1 µg and higher. The activity was dose-dependent, being optimum at 1 µg with 90% and 80% of males contacting with the source in the presence of theZ-1 andZ/E-1, respectively. 11-Hexadecynyl acetate (2) functioned as a pheromone mimic, being able to induce the complete mate-finding behavioral sequence, although its activity was much lower than that of the pheromone. (Z)-13-Hexadecen-11-ynyl alcohol (3) and, particularly, (Z)-13-hexadecen-11-ynal (4) were potent inhibitors of the upwind flight response in mixtures withZ-1 in 99:1, 95:5, and 91:9 ratios. (Z)-1,1,1-Trifluoro-16-nonadecen-14-yn-2-one (5) also inhibited the response of males to pheromone, particularly in the source contact behavior. Comparison with activity displayed by analogs in field tests is also reported.

The Influence of Fluorinated Molecules (Semiochemicals and Enzyme Substrate Analogues) on the Insect Communication System

Can the introduction of fluorine atoms affect the bioactivity of natural semiochemicals? Can fluorine contribute in the creation of specific enzyme inhibitors to interrupt or disrupt the insect communication system? The first step for the bioactivity of a molecule is interaction with the biological sensor. Hydrogen and fluorine are almost bioisosteric and the receptor site of the enzyme can still recognize and accept the fluoro analogue of its natural substrate. However, the peculiar electronegativity of the fluorine atom can affect the binding, absorption, and transport of the molecule. The differences in the molecule's electronic properties can lead to differences in the chemical interactions between the receptor and the fluorinated substrate. Fluorine introduction can modify the metabolic stability and pathway of the semiochemicals in many different ways. Fluorinated analogues can show synergism, inhibition, or hyperagonism effects on insect behaviors, that is, the activity of the nonfluorinated parent compounds can be mimicked, lost, or increased. In any case, the fluorinated molecules can interact with the bioreceptors in a new and disrupting way. The semiochemicals are olfactory substances: fluorine can affect their volatility or smell. Production of semiochemicals from exogenous substances, perception at antennal receptors, and processing of biological responses are the main steps of communication among insects. In the production step, the fluorinated molecules can interact with enzymes that catalyze the biosynthesis of the natural pheromones. In the perception step, fluorinated semiochemicals can interact with the olfactory receptor cells; this often leads to totally unpredictable behaviors. Fluorinated molecules have been developed as probes to elucidate the complex chemorecognition processes of insects. Many of these molecules have been tested to find highly effective behavior-modifying chemicals. New analogues have been synthesized to investigate the metabolic pathway of a pheromone molecule and many of them are promising disrupting agents. Despite such titanic research efforts, the results have often been random, rational trends in the induced behaviors have sometimes been impossible to find, and practical applications of the fluorinated semiochemicals are still uncertain.

Ligand specificity of pheromone-binding proteins of the processionary moth

Photoaffinity labeling of proteins extracted from sensory hairs and antennal branches of the processionary moth Thaumetopoea pityocampa with a tritium-labeled diazoacetate analogue of the sex pheromone (Z)-13-hexadecen-11-ynyl acetate revealed a 15-kDa pheromone-binding protein in male moth sensory hairs (SH-15). A different 15-kDa protein in male antennal branches (B-15) was not photolabeled. All extracts except male sensory hairs showed a photolabeled 20-kDa protein; a photolabeled male 30-kDa protein in the branches (B-30) was also observed. The 20-kDa proteins in the sensory hairs (SH-20) and branches (B-20) showed differing affinities for the photoaffinity analogues; moreover, SH-15 exhibits higher affinity for the natural pheromone, (Z)-13-hexadecen-11-ynyl acetate, than for its alcohol metabolite and other analogues in competitive displacement experiments. The affinity shown by the pheromone-binding protein for the metabolic product suggests that the alcohol may be also transported by the binding protein. Interestingly, a shift in labeling from SH-15 to SH-20 was produced in the presence of an excess of the natural pheromone, its alcohol and other analogues. The binding showed little discrimination among structurally similar analogues of the pheromone, while saturated and aromatic molecules showed little affinity for the proteins of either sensory hairs or antennal branches.