Imen Saïd, Christian Malosse, Virginie Durier, Colette Rivault
Faculté des Sciences de Gafsa, Université de Gafsa, Campus Zarroug, 2112 Gafsa, Tunisia.
Unité de Spectrométrie de Masse Structurale et Protéomique, Institut Pasteur, 75015 Paris, France.
Environ Entomol. 2015 Jun;44(3):713-23. doi: 10.1093/ee/nvv035. Epub 2015 Mar 31.
Chemical communication is necessary to induce aggregation and to maintain the cohesion of aggregates in Periplaneta americana (L.) cockroaches. We aimed to identify the chemical message inducing aggregation in this species. Two types of bioassays were used-binary choice tests in Petri dishes and tests in Y-olfactometer. Papers conditioned by direct contact of conspecifics induce aggregation when proposed in binary choice tests and were attractive in a Y-olfactometer. The identification of the molecules present on these conditioned papers indicated that dichloromethane extracts contained mainly cuticular hydrocarbons whereas methanol extracts contained more volatile molecules. Only a mixture of extracts in both solvents induced aggregation. High concentrations of cuticular hydrocarbons are necessary to induce aggregation when presented alone. When presented with volatile molecules present in methanol extracts, low concentrations of cuticular hydrocarbons are sufficient to induce aggregation if they are presented in contact. Among volatile molecules collected on filter paper, a mixture of three compounds-hexadecanoic acid, pentadecanoic acid, and pentaethylene glycol-induced aggregation. Our results provide evidence that aggregation processes in P. americana relies on a dual mechanism: attraction over long distances by three volatile molecules and maintenance on site by contact with cuticular hydrocarbons.
化学通讯对于诱导美洲大蠊（Periplaneta americana (L.)）聚集并维持聚集体的凝聚力是必要的。我们旨在确定诱导该物种聚集的化学信号。使用了两种类型的生物测定法——培养皿中的二元选择试验和Y型嗅觉仪试验。在二元选择试验中，与同种个体直接接触而被处理过的滤纸能诱导聚集，并且在Y型嗅觉仪中具有吸引力。对这些处理过的滤纸上存在的分子进行鉴定表明，二氯甲烷提取物主要含有表皮碳氢化合物，而甲醇提取物含有更多挥发性分子。只有两种溶剂提取物的混合物才能诱导聚集。单独呈现时，高浓度的表皮碳氢化合物是诱导聚集所必需的。当与甲醇提取物中存在的挥发性分子一起呈现时，如果表皮碳氢化合物以接触的方式呈现，低浓度就足以诱导聚集。在滤纸上收集的挥发性分子中，十六烷酸、十五烷酸和五乙二醇这三种化合物的混合物能诱导聚集。我们的结果提供了证据，表明美洲大蠊的聚集过程依赖于一种双重机制：三种挥发性分子在远距离产生吸引力，与表皮碳氢化合物接触在原地维持聚集。
