Nepetalactones from essential oil of Nepeta cataria represent a stable fly feeding and oviposition repellent.

The stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), is one of the most serious pests to livestock. It feeds mainly on cattle and causes significant economic losses in the cattle industry. Standard stable fly control involving insecticides and sanitation is usually costly and often has limited effectiveness. As we continue to evaluate and develop safer fly control strategies, the present study reports on the effectiveness of catnip (Nepeta cataria L.) oil and its constituent compounds, nepetalactones, as stable fly repellents. The essential oil of catnip reduced the feeding of stable flies by >96% in an in vitro bioassay system, compared with other sesquiterpene-rich plant oils (e.g. amyris and sandalwood). Catnip oil demonstrated strong repellency against stable flies relative to other chemicals for repelling biting insects, including isolongifolenone, 2-methylpiperidinyl-3-cyclohexen-1-carboxamide and (1S,2'S)-2-methylpiperidinyl-3-cyclohexen-1-carboxamide. The repellency against stable flies of the most commonly used mosquito repellent, DEET, was relatively low. In field trials, two formulations of catnip oil provided >95% protection and were effective for up to 6 h when tested on cattle. Catnip oil also acted as a strong oviposition repellent and reduced gravid stable fly oviposition by 98%.

Effects of stable flies (Diptera: Muscidae) on weight gains of grazing yearling cattle.

Differences in weight gains caused by stable flies, Stomoxys calcitrans (L.), on grazing yearling steer/calves averaged 0.2 kg per steer in a 3-yr study on canyon range pastures in West Central Nebraska, Stable fly numbers averaged 0.85 per front leg on treated calves and 3.64 per front leg on control calves. In 2 of the 3 yr after the grazing trials were completed, the calves were placed in a feedlot and fed a finishing ration. Compensatory gain did not occur in the feedlot after the stable fly stress was removed.

Comparative efficacy of several insecticides for control of cattle lice (Mallophaga: Trichodectidae and Anoplura: Haematopinidae).

Several insecticides were applied to cattle at various rates, mixtures, application methods and numbers of treatments and evaluated for control of cattle lice. The insecticides included permethrin at various rates as a pour-on with and without the synergist piperonyl butoxide (PBO), and also at various rates as a spray with and without PBO. Pirimiphos-methyl was evaluated as a pour-on at various rates and with one or two applications. Lambda cyhalothrin in microencapsulated formulation was compared to a non-microencapsulated formulation. Rabon(R) was applied as a pour-on at two rates and at one or two treatments for each rate. Dimilin(R) was applied as a pour-on at two rates and mixed with permethrin and applied at two rates. Five endectocides, Eprinex(R), Ivomec(R), Dectomax(R), Cydectin(R) and Phoenectin(R) were all applied at the same rate. The cattle utilized in this research were all infested with a mixture of lice species. The species included: Bovicola (Damalinia) bovis (L.), Haematopinus eurysternus (Nitzsch), Linognthus vituli (L.) and Solenoptes capillatus (Enderlein). Most of the cattle were infested with at least two species and some had three or all four species present. All of the treatments except permethrin 1.0%+5% PBO, at a rate of 3ml/45.4kgwt. provided acceptable lice control with one application. Data indicated that applying the insecticides in early January should provide enough control to render the need for a second treatment unnecessary.

Calculating economic injury levels for stable flies (Diptera:Muscidae) on feeder heifers.

A procedure for calculating the economic injury levels for stable flies, Stomoxys calcitrans (L.), on feeder heifers was developed from reduction of average daily weight gain-stable fly population level data in 8 independent replicated experiments over 17 yr. A negative exponential was fitted to the data using nonlinear regression. Regression coefficients were then used to derive a simple predictive equation for calculating the economic injury level in relation to cost of controlling stable flies in the feedlot, and the market value of heifers. Examples for calculating the economic injury level under practical feedlot situations are presented. Also included are recommendations for a simple random sampling design for stable flies in feedlots.

Average daily gains of Brahman-crossbred and English x exotic feeder heifers exposed to low, medium, and high levels of stable flies (Diptera: Muscidae).

Brahman-crossbred and English x Exotic feeder heifers were exposed to low (5 per leg), medium (12 per leg), and high (30 per leg) stable fly, Stomoxys calcitrans (L.), population levels to test relative tolerance of these cattle breeds to stable flies. The Brahman-crossbred heifers were tolerant to stable flies only when they were 12-13 mo old. At the same age, the English x Exotic heifers sustained reductions in average daily gain (ADG) at all three stable fly population levels of 0.22 kg/d (11.2%). At 14-15 mo of age, both breeds were affected only by the high stable fly level. The reduction in ADG was approximately 0.16 kg/d (10.6%) for both breeds. Stable fly numbers on the heifers varied with time of day. Both breeds appeared equally attractive to stable flies. With or without stable flies, the Brahman-crossbred heifers consistently gained less weight than the English x Exotic heifers by 0.24 kg/d (15%).