Effects of Fatty Acid and Geraniol Repellent-Oil Mixtures Applied to Cattle on Blood Feeding and Reproductive Parameters in Field Populations of Haematobia irritans (Diptera: Muscidae)

Abstract

California pastured cattle were treated with 250 ml of a 15% mixture of fatty acids (C8-C9-C10) or 125 ml of 2% geraniol in a mineral oil carrier to assess impacts on horn flies, Haematobia irritans (L.) (Diptera: Muscidae) over two summers. Horn flies were netted from cattle every 3-4 d for 2 wk before treatment, 2 wk during treatment (four treatments, with flies collected before each treatment), and 2 wk after treatments ceased. Blood meal weights were estimated by hemoglobin assay of excised abdomens. Other females were dissected to determine the number of active ovarioles and the stage of primary follicle development. Depending on year and herd, pretreatment males contained an average of 0.6-1.0 mg of blood, while females contained 1.7-2.7 mg. Pretreatment egg development (least developed oocytes were stage 1 and fully developed eggs were stage 5) averaged 3.7-4.3, and number of active ovarioles averaged 18.1 to 19.6/female. During treatment periods, significant reductions in blood weight were noted for females, but usually not for males, and females also often exhibited reduced mean oocyte stage and number of active ovarioles. Peaks in proportions of young nulliparous females (oocyte stages 1 or 2) were seen during some repellent application periods. This suggested older females had been killed or driven off from the local population by the treatments, and flies on cattle included more young flies that likely were recent arrivals. The repellent-oil mixture thus impacted blood feeding, reproductive fitness, and probably age structure in the field.

Chemosensory-Related Gene Family Members of the Horn Fly, Haematobia irritans irritans (Diptera: Muscidae), Identified by Transcriptome Analysis

“…Integration of push-pull strategies in the management of livestock pests is a viable option for controlling pest fly populations [90]. The identification of natural product compounds that successfully repel horn fly adults and the evidence of repellent effectiveness in the field [8][9][10][11][12][13][14], while short-lived, supports the pursuit of this tool as an option for non-pesticide fly control. A further understanding of horn fly chemosensory pathways will provide additional targets for pest control development.…”

“…The repellent effect of geranium, lemongrass, peppermint, catnip, geraniol, and coconut oil constituents have been documented against horn flies in a laboratory setting [8][9][10][11]. Further, on-animal, field evaluation of the repellency of medium chain length fatty acid derivatives and 2% geraniol against the horn fly suggested these compounds impacted the mating status of on-animal populations and were effective at reducing blood-feeding by female horn flies and at repelling older females [12][13][14]. While the duration of activity is currently limited and the desired response can require large quantities of compound, the results are promising.…”

A push–pull strategy to suppress stable fly (Diptera: Muscidae) attacks on pasture cattle via a coconut oil fatty acid repellent formulation and traps with m‐cresol lures

“…11,12 Biorational compounds with repellent activity are potential alternatives to pyrethroids to prevent stable fly feeding on pasture cattle. [13][14][15] Repellent plant essential oils derived from catnip and geranium and fatty acid mixtures have demonstrated activity against biting flies. 13,16,17 A trial with catnip oil in a soybean and paraffin wax solution showed promising spatial repellency against stable flies.…”