Toxicity of imidacloprid and chlorpyrifos against German cockroaches Blattella germanica

Abstract

Background and Aim: As a mechanical vector of some communicable diseases and a self-adaptive species to human environments, the German cockroach can transmit pathogens, such as bacteria, viruses, and fungi, to human beings. This study was conducted to determine the toxicity of imidacloprid and chlorpyrifos against German cockroaches. Materials and Methods: In this experimental study, the last instar German cockroach nymphs were used to test their sensitivity to imidacloprid and chlorpyrifos insecticides by the contact and bait methods. In bioassay (jar test), the nymphs were isolated from the main colony and were exposed to the insecticides for 30 min. The mortality rate was recorded 24 h after the recovery time. In bioassay (bait), 24-96 h after exposure to the poisonous bait, the mortality rate was recorded and regression analysis was run to analyze the data in the SPSS software (IBM, Chicago, USA). Results: The lethal doses (LD) of imidacloprid and chlorpyrifos were 9.5 mg/m2 and 39.78 mg/m2, respectively. The LD50 for imidacloprid and chlorpyrifos were 2.66 and 9.92 mg/m2, respectively. Results revealed that the highest concentration of imidacloprid (45%) could cause the highest mortality rate (95%) 24 h after exposure. There is a significant difference in the mortality of the samples during the follow-up period. Moreover, the chlorpyrifos smeared bait, with a concentration of 16% after 24 h, had the highest mortality rate (95%). Conclusion: The highest mortality rate occurred in the ingestion of imidacloprid smeared bait within the first 48 h after being exposed to the insecticide. Therefore, the results show that imidacloprid can prove significantly effective in controlling cockroaches.

Laboratory efficacy and toxicology of two commercial insecticides (deltamethrin and fenitrothion) against two German cockroach field strains

“…Pest management professionals tackle this pestiferous insect with several chemical classes and formulations. Much of the research on insecticidal toxicity and efficacy has been done on adult cockroaches, but little is known about this species' nymphs [ 20 ]. Insecticidal toxicity and efficacy on nymphs should be studied as well, as insecticides used in the field expose all stages of cockroaches.…”

“…Insecticidal toxicity and efficacy on nymphs should be studied as well, as insecticides used in the field expose all stages of cockroaches. Furthermore, laboratory research on the efficiency of insecticides on German cockroaches at the nymphal stage is lacking compared to the adult stage [ 20 ].…”

The effectiveness of Fipronil active substances compared with imidacloprid to control Germany’s cockroaches (Blatella germanica L.)

“…This chemical is used to control pests by interfering stimulation transmission in the insect's nervous system. It occurrs because imidacloprid affects nicotinic acetylcholine receptors in the insect central nervous system [10].…”