Efficacia di nuove molecole sinergizzanti nei confronti di Blattella germanica (L.)

[Autom. eng. transl.] One of the insects infesting the most widespread anthropogenic environments globally is Blattella germanica (L.). In this species, resistance to insecticides has grown over the years and has become one of the major obstacles to the implementation of efficient control strategies. Currently, insecticidal baits with gel formulations maintain good efficacy, while conventional treatments that involve the use of spray formulations, especially pyrethroids, have shown many limitations. In the literature there are numerous cases of ineffectiveness for various active ingredients against B. germanica, making it the second most resistant urban insect in the world ranking. A possible solution to this problem can come from the use of synergists such as piperonyl butoxide (PBO), molecules without or with negligible insecticidal activity which, when applied in combination with various insecticidal products, enhance their effectiveness by inhibiting the metabolic systems of detoxification present in the target insect. In this study, carried out within the European project "Ecosyn" (EcoSyn - Ecofriendly synergists for insecticide formulations, funded by the Seventh Framework Program of the European Union - Contract no 605740), the PBO and some of its new derivatives were combined with insecticides already known efficacy, such as cypermethrin and S-metoprene, to evaluate their possible synergistic effect. For the tests with the pyrethroid, a contact test was developed by leaving the insects in contact with the treated surface for 30 minutes and evaluating the knock-down effect every 5 minutes. Mortality was assessed after 24 hours. In general, the various synergists did not increase the knock-down effect but caused a significant increase in mortality compared to the insecticide used alone. Only one of the new derivatives has shown, when used alone, a limited toxicity towards B. germanica. The experiment with S-metoprene was carried out by administering only to virgin females wet baits containing insecticide and synergistic, for a week. After mating with untreated males, both mortality and the appearance, abortion or hatching of the ootheca were measured every day. The data, albeit with differences between the various synergists, show that the treated cockroaches, compared to the control ones, have a delay in the formation of the oothecae, an increase in the percentage of abortions of the same and a reduction in the number of births.