Influence of different adhesive substances and the in vitro test's effectiveness response for the evaluation of Dinotefuran associated with Pyriproxyfen on the eggs of Ctenocephalides felis felis (Siphonaptera, Pulicidae)
methodology, in vitro, flea
The present study aimed to evaluate the influence of three sticky substances on the development of flea Ctenocephalides felis felis eggs until adulthood and apply this methodology to evaluate the action of the formulation containing dinotefuran and pyriproxyfen. In the first step, the following adhesive substances were tested: stick glue, liquid silicone and instant adhesive glue (cyanoacrylate). For each substance, 10 eggs per plate were used, with 10 repetitions. The eggs were obtained from a laboratory colony. The hatching larvae were counted at day 7 and larval medium were placed into incubators maintained at 27 ± 1ºC and 80% relative humidity. The number of adult fleas was counted at day 30. For the in vitro efficacy test, two animals of the feline species received a single dose of a topical formulation containing the adulticide dinotefuran and an insect growth regulator pyriproxyfen and two animals received no treatment, maintained as controls. Animal infestations were carried out on days +35, +42, +49, +54, +63, +70 and +77 and egg collections were always performed 48 hours after infestation, on days +37, +44, + 51, +56, +65, +72 and +79. Three repetitions were prepared with 10 eggs each, according to the methodology and using the sticky substance with the best performance in the previous step and calculating the effectiveness for each time point. The results of the first step of the 100 eggs incubated by each substance, 64, 51 and 76 larvae developed up to the third stage, respectively for the glue stick (CB), cyanoacrylate (CA) and liquid silicone (SL) groups. Among these incubated larvae, 59, 45 and 68 adults developed until adulthood, respectively in the CB, CA and SL groups. The percentage of adults recovered related to the number of incubated larvae, respectively to CB, CA and SL, was 92.2%, 88.2% and 89.5%. However, the substance of choice for the methodology was liquid silicone due to its excellent recovery of larvae compared to eggs incubated and the usefulness of the technique placing the glue on the Petri dish. Regarding the evaluation of dinotefuran and pyriproxyfen, the percentage of egg hatching inhibition was above 90% on D + 44 and dropped to 18.5% on D + 72 and the efficacy against emergence of adults was 100% on the day +44 and 23.8% on the day +72. Based on the results, it was possible to evaluate the liquid silicone sticky substance did not influence the development of larvae through an in vitro methodology, being applicable to monitor the development of flea’s larvae and pupas under the influence of an insect growth regulator, as well as the emergence of adults. Therefore, from this method, it is concluded that the combination of dinotefuran and pyriproxyfen was effective in interrupting the cycle of C. felis felis.