Utilization of yeast metabolites for bioattraction of cockroach

Abstract

Cockroaches are among the most persistent pests that thrive in protected locations all over the world. Cockroach control using insecticides and other chemicals are not desirable because they are toxic to organisms and the environment. Pests can develop resistance to the chemicals, and chemical raw materials are from unsustainable source. This study was aimed to identify the novel potential of locally isolated yeasts, namely Pichia kudriavzevii M12 and Candida ethanolica M2 in cockroach attraction. The yeasts were fermented in potato dextrose broth (PDB) up to a week and tested for bioattraction of cockroaches at six locations at the student residential halls at Universiti Teknologi Malaysia (Johor, Malaysia). Either the 1-day or 4-day fermented broth from the yeasts were placed as the baits on sticky trap overnight in order to attract cockroaches. Freeze drying on the fermented broth was carried out and the resultant powder was sprinkled on the cockroach trap and tested for cockroach attraction. PDB was used as control. The 4-day fermented PDB of P. kudriavzevii M12 was found to be the better cockroach attractant, which trapped the highest number of both nymphs and adult cockroaches (an average of 48 cockroaches per catch). Ssuccessive attraction was done consecutively at the same location after two weeks, which resulted in a decrease of almost 80% of the cockroach population at the studied location. The metabolites in the 4-day fermented PDB of P. kudriavzevii M12 were profiled by liquid chromatography-mass spectrometry (LC-MS/MS), thus revealing the presence of secondary metabolites from the yeast strain for cockroach attraction. A total of 44 exometabolites with diverse properties and structures were identified and many were intermediates and products of the central metabolic pathway such as lipids, carboxylic acids and esters. In conclusion, P. kudriavzevii M12 showed a great potential as an eco-friendly cockroach attractant and the attraction could be as a result of the metabolites produced.