Plant-derived semiochemicals for the attraction of stable fly, Stomoxys calcitrans to host plants and fitness value of nectar feeding

Abstract

Stable fly (Stomoxys calcitrans) is a serious vector of many livestock diseases of medical and veterinary importance. Unlike their blood-feeding characteristics, which are widely studied, little information about S. calcitrans plant feeding nectar is unknown. According to this study, the plant-feeding behaviour of field-collected stable flies was determined by detecting coding (rbcL) and the non-coding (trnH-psbA) regions of the chloroplast gene. From the three study regions (Icipe- Duduville campus, Mpala research centre, and Amboseli), 3.67% of field-collected stable flies were positive for the following seven plant species: Parthenium hysterophorus, Terminalia brownii, Senegalia mellifera, Vachellia xanthophloea, Allium sativum, Lantana camara, and Schinus terebinthifolia. The fitness benefits of plant feeding in adult stable flies was investigated using flowering Parthenium hysterophorus as a representative plant nectar source because it is readily available and can be grown in pots. Supplementing blood-feeding with flowering P. hysterophorus had no significant effect on S. calcitrans egg-laying and survival but significantly enhanced egg hatchability compared to blood alone. This variation suggests an additional resource acquired from plant feeding, which enhances egg fertility in S. calcitrans compared to feeding on blood alone. The plant volatiles demonstrated a great chemodiversity between the different plant species. From both laboratory behavioural assays and field experiments, the behavioural response of stable flies to plant-derived volatile organic compounds varied from attraction, neutral to repellency. Blood feeding is very important for egg development in adult flies, and supplementing blood-feeding with plant nectar improves eggs' hatchability, which will lead to an increased vector population. Results from this work contribute largely to a better understanding of stable flies' survival, reproduction, and disease transmission and the possibility of applying plant odours in the surveillance and control of stable flies.