Toxicological Impacts of Certain Pesticides on Subtrrenean Termite, Coptotermes alexandrines, and Drywood Termite, Cryptotermes brevis

Abstract

<title>Abstract</title> This study aimed to identify the similarity between the subterranean termite, <italic>Coptotermes alexandrines</italic> , and the drywood termite, <italic>Cryptotermes brevis</italic> , which are dominant in Alexandria City, Egypt, using RAPD-PCR as well as to assess the acute toxicity by a paper contact method and biochemical effects ( <italic>in vivo</italic> and <italic>in vitro</italic> inhibition of acetylcholinesterase (AChE) and cellulase (CE-ase)) of different insecticides such as chlorpyrifos, fipronil, emamectin benzoate, imidacloprid, lambada-cyhalothrin, boric acid, and methyl eugenol belong to different chemical groups on termites. RAPD primers have been used to identify the genomic DNA of the subterranean and drywood termites, where positive correlations and 8 haplotypes were observed for both species of termites providing information on the spread of species,, identifying the adapted populations, and distinguishing termite species from out of Alexandria.Based on the toxicity index values (TI), chlorpyrifos and methyl eugenol exhibited the highest TI value against subterranean and drywood termites, respectively, and the tested pesticides were more toxic to drywood termites than subterranean termites. Different degrees of inhibition of AChE and CE-ase in LC ₅₀ -exposed termites 24 h after treatment surviving the assays and <italic>in vitro</italic> were obtained and chlorpyrifos was the most potent to inhibit the enzymes either in <italic>C. alexandrines</italic> or <italic>C. brevis.</italic> Additionally, chlorpyrifos competitively inhibited AChE with more affinity towards this enzyme. <italic>C. alexandrine</italic> and <italic>C. brevis</italic> had different susceptibilities to the tested pesticides due to their different amounts of protein content.