Enantioselective synthesis and absolute configuration of the sex pheromone of Hedypathes betulinus (Coleoptera: Cerambycidae). Tetrahedron Lett.

a b s t r a c t The male-produced sex pheromone of Hedypathes betulinus was identified as a mixture of (E)-6,10-dimethyl-5,9-undecadien-2-one (geranylacetone) (1) and its respective alcohol (2) and acetate (3). Kinetic resolution of alcohol (2) promoted by CAL-B in organic media provided both, (R)-(À)-(E)-6,10-dimethyl-5,9-undecadien-2-yl acetate (3) and (S)-(+)-(E)-6,10-dimethyl-5,9-undecadien-2-ol (2) in high enantiomeric purity. Comparative GC analysis using a chiral column revealed the natural constituents as being (R)-(3) and a mixture of (R)-and (S)-(2) in a ratio of 82.3% and 17.6%, respectively. Ó 2010 Elsevier Ltd. All rights reserved. Hedypathes betulinus (Coleoptera: Cerambycidae: Lamiinae) (Klug, 1825) is the most serious pest of green mate (Ilex paraguariensis) in the southern region of Brazil. 1 Three male-specific components were detected by gas chromatography, and the presence of a pheromone regulating the mating behavior of this insect was determined. 2 The compound (E)-6,10-dimethyl-5,9-undecadien-2-ol (2) was identified as the main component of the sex pheromone of Tetropium fuscum and Tetropium acinnamopterum and was named fuscumol 3 , whereas (E)-6,10-dimethyl-5,9-undecadien-2-yl acetate (3) is unprecedented in pheromone chemistry. Behavioral tests using the synthetic racemic compounds showed that these compounds are attractive for female H. betulinus. 2 However, the presence or absence of the unnatural isomer may have an influence on the behavior of the insects, supporting the importance of knowing the stereochemistry of naturally produced compounds. 4 H. betulinus aeration extracts provided a few microgram of each compound, making it impractical to use conventional methods of absolute configuration assignment. 2 Therefore, the best way to establish the absolute configuration of the pheromone is by enantioselective gas chromatography and comparison of retention times of synthetic enantiomers with corresponding data of the natural compounds. Racemic alcohol (2) and acetate (3) were synthesized by the reduction of geranylacetone (1) with LAH 6 , followed by acetylation of the hydroxyl group using Ac 2 O and pyridine 7 to afford alcohol (2) and acetate (3) in 90% and 85% yield, respectivel

Insecticidal Activity of Compounds of Plant Origin on Mahanarva spectabilis (Hemiptera: Cercopidae)

The damage caused by spittlebugs varies according to the species of grass, and the losses can reach alarming levels. Measures for population control are currently restricted to the use of resistant grasses and the diversification of pastures. Therefore, alternative control measures are necessary, such as the use of botanical insecticides. The aim of this study was to evaluate the insecticidal activities of thymol, carvacrol, eugenol, cinnamaldehyde, and trans-anethole on Mahanarva spectabilis eggs, nymphs, and adults under laboratory conditions. In the egg tests, treatments with eugenol, carvacrol, and thymol showed the highest mortalities, presenting efficiencies higher than 85% after 48 h of application. In the nymph tests, the treatments with thymol and carvacrol at 2.5% and eugenol at 2.0% and 2.5% showed intermediate efficiencies, with values above 61%. The highest mortality was observed in the treatment with trans-anethole at 2.5%, with an efficiency of 95%. In the tests with adults, only treatment with trans-anethole at 2.5% obtained an efficiency reaching 90%; in the other treatments, the efficiency did not exceed 51%. These results showed that, at these concentrations, trans-anethole presents a high rate of insecticidal activity on M. spectabilis nymphs and adults and, therefore, is recommended as a potential natural insecticide for the control of this pest

Sperm depletion: a cost for single mated females of Podisus nigrispinus (Dallas, 1851) (Heteroptera: Pentatomidae)

The aim of this work was to test if egg viability of polyandrous females was increased with increasing number of matings. Longevity and reproductive output of females of the predatory stinkbug Podisus nigrispinus that were allowed to mate for 0, 1, 2, 3 times or were in the continuous presence of the same male was evaluated. Polyandry resulted in diminished sperm depletion. Females that had mated three times or that were in continuous presence of a male produced more offspring than females that mated once or twice throughout their lifetime. There was a negative correlation of mating history on female longevity. Results indicated that remating, either with same male or with different males were crucial for maximization of the reproductive success of females.<br>Entre os heterópteros, o declínio da concentração de esperma pode ser um fator limitante para o sucesso reprodutivo desses insetos. Acasalamentos múltiplos conferem um reabastecimento de esperma e podem permitir um aumento do valor adaptativo das fêmeas. Neste estudo foi testada a hipótese de que a poliandria aumenta a viabilidade dos ovos. A longevidade de fêmeas de Podisus nigrispinus, bem como seus parâmetros reprodutivos em resposta a diferentes números de acasalamentos (0, 1, 2, 3 ou em coabitação com o mesmo macho) foi avaliada. Esse percevejo vem sendo usado em programas de controle biológico de pragas em reflorestamentos de Eucalipto no Brasil. Apesar da diminuição no tempo de sobrevivência das fêmeas, acasalamentos múltiplos mantiveram a viabilidade dos ovos e o período reprodutivo das fêmeas, permitindo um maior número de descendentes produzidos. Tais resultados indicam que um número mínimo de três acasalamentos antes da primeira postura permite uma maximização do sucesso reprodutivo dessa espécie