Evaluation of novel ecofriendly synergists for insecticide formulations against Blattella germanica (L.)

Blattella germanica (L.) is a common pest of anthropic environments. Cockroach infestations are associated with poor sanitation, particularly around food-handling facilities, causing damages and contaminations. Furthermore, this species is responsible for transmitting microorganisms which implicate medical and hygienic problems. In this study, carried out in the framework of the European project "Ecosyn" (Ecofriendly synergists for insecticide formulations, funded by the 7th Framework Program of the European Union, contract no. 605740), the synergists PBO and some of its new derivatives were combined with two insecticides to assess any possible effect. The cypermethrin was assayed using a contact test in vials, leaving the insects with the products for 30 minutes, evaluating the knock-down effect every 5 minutes. Then, cockroaches were transferred in untreated vials and mortality was assessed 24 hours later. In general, the synergists did not influence the knock-down effect but caused a significant increase in mortality compared to the insecticide used alone. The S-methoprene effect was evaluated feeding virgin females for a week with moist baits containing insecticide and synergist. After mating with untreated males, every day mortality and appearance, abortion or hatching of ootheca were assessed. Although differences among various synergists were observed, the treated cockroaches showed a delay in ootheca production, an increase in its abortion and a reduction in the number of births.