Chemical composition and influence of essential oil from Croton pulegiodorus Baill. Leaves on the nutrition and survival of Sitophilus zeamais Mots. (Coleoptera: Dryophthoridae) as well as survival and behavior of Nasutitermes corniger Mots. (Blattodea: Termitidae)

Abstract

Essential oils have been studied to develop sustainable alternatives for controlling pest-species. This study determined the chemical composition and toxicity of an essential oil from Croton pulegiodorus leaves against Sitophilus zeamais and Nasutitermes corniger. Ascaridole (22.75%) and camphor (18.11%) were the major compounds. The essential oil showed toxicity upon ingestion on S. zeamais, with LC₅₀ and LC₉₀ of 24.24 and 46.76 μL/g for 15 days, respectively. It presented a moderate (10.0 and 12.5 μL/g) to strong (15 μL/g) deterrent effect, interfering with nutritional parameters, causing a reduction in the relative consumption rate, relative biomass gain rate and efficiency in conversion of ingested food. Furthermore, it stimulated in vitro S. zeamais β-D-xylanase (+33.39%), endoglucanase (+8.28%), exoglucanase (+84.77%), and α-amylase (+359.18%) activities and reduced in vitro the activity of trypsin-like enzymes (−79.67%). The essential oil showed fumigant effect against N. corniger termites with LC₅₀ and LC₉₀ (24 h) of 0.57 and 3.26 μL/mL of air for workers and 1.63 and 4.74 μL/mL of air for soldiers respectively. In workers, it caused 100% mortality through contact in 2.08 and 0.49 min (at 0.4 μL/μL and neat oil). A significant increase in the number of self-cleaning and falls indicated behavioral changes induced by the oil in N. corniger workers. The study shows the potential of the essential oil of C. pulegiodorus leaves as an alternative method in the management of maize weevil and N. corniger.