Primary Screening of German Chamomile Oil as Insecticides, Baits, and Fumigants in Nanoformulations against the Health Pest Periplaneta americana (L.) (Dictyoptera: Blattidae)

Abstract

Cockroaches are household pests with a health risk to humans. Natural products may have insecticidal activities against pest insects and thus inspire the development of novel insecticides as "biopesticides". In this study, we report a strategy to prepare nanoparticles of German chamomile (Matricaria chamomilla L.) oils (= essential oils or EO) to control the American cockroach in the two forms: one is coated with polyethylene glycol (PEG) as nanocapsiolation (NC) and the other is loaded with oil as a nanoemulsion (NE). First, the nanoformulations were prepared and characterized by evaluating droplet size, zeta potential, polyspersion index and morphology. The compounds of EO were also analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). A complete FTIR characterization was made to confirm the formation of EO-PEG composite. In a fumigant bioassay, EO and NE caused 100% and 44.44% mortality of cockroaches at 10 mg/ liter after 1 h and 72 h of application, respectively. In a dusting toxicity bioassay, NC caused 100% mortality at 1.5 mg/500 ml after 24 h. Overall, the obtained results suggested that the oil-based nanoformulations could serve as an alternative method for producing biopesticides to overcome the disadvantage of the natural and semisynthetic pesticides and to increase their efficacy to control cockroaches. In addition, the PEG improved the stability of oil products and increased their dispersion in the aqueous phase. Although we found the essential oils of German chamomile could be useful to control the cockroaches, the techniques should be improved the nanoformulations to obtain practical effectiveness.