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.

BACKGROUND: Stable flies [Stomoxys calcitrans (L.)] are economically important pests of cattle and other livestock. As an alternative to conventional insecticides, we tested a push-pull management strategy using a coconut oil fatty acid repellent formulation and an attractant-added stable fly trap. RESULTS: In our field trials we found that weekly applications of a push-pull strategy can reduce stable fly populations on cattle as well as a standard insecticide (permethrin). We also found that the efficacy periods of the push-pull and permethrin treatments following on-animal application were equivalent. Traps with an attractant lure used as the pull component of the push-pull strategy captured sufficient numbers of stable flies to reduce on-animal numbers by an estimated 17-21%. CONCLUSIONS: This is the first proof-of-concept field trial demonstrating the effectiveness of a push-pull strategy using a coconut oil fatty acid-based repellent formulation and traps with an attractant lure to manage stable flies on pasture cattle. Also notable is that the push-pull strategy had an efficacy period equivalent to that of a standard, conventional insecticide under field conditions. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Detection of bovine viral diarrhea virus in stable flies following consumption of blood from persistently infected cattle.

Control of bovine viral diarrhea virus (BVDV) relies on resource-intensive sampling to detect and remove persistently infected (PI) cattle. Herd-level surveillance tools would be useful for herds with unknown BVDV status and for monitoring herds with BVDV-free status. Our objective was to determine the feasibility of using stable flies as a sampling tool to detect BVDV at the herd level. Stable flies (Stomoxys calcitrans) were fed citrated blood from either BVDV-PI or BVDV-free cattle to establish pools of 100 flies with various proportions of BVDV-fed flies (0%, 1%, 10%, 20%, 40%, or 100% in each pool). BVDV-fed flies in these pools were harvested either 1, 2, or 3 d after consuming BVDV-PI blood to determine the impact of time after feeding. Two replicates of a 3-d by 6-dilution level matrix were produced. BVDV RNA was consistently detected on day 1 when ≥10% of the flies in the pool consumed PI blood. On days 2 and 3, positive BVDV RNA detection was variable and became less consistent. Our results demonstrate that BVDV RNA can be detected in stable flies after feeding on blood from PI cattle. Successful use of stable flies as a surveillance tool will require validation under field conditions.

Comparisons of antifeedancy and spatial repellency of three natural product repellents against horn flies, Haematobia irritans (Diptera: Muscidae).

BACKGROUND: Horn flies are among the most important biting fly pests of cattle in the United States. Horn fly management is largely dependent upon pesticides, which ultimately leads to the rapid development of insecticide resistance. Alternative control strategies, including repellents, have shown promising results in reducing fly biting. In the present study, we examined the efficacy and longevity of recently identified natural product repellents against horn flies. RESULTS: Catnip oil, geraniol and C8910 acids reduced horn fly feeding in a laboratory bioassay and also exhibited spatial repellency in the olfactometer. Residual activity was observed for up to 3 days in laboratory assays; however, 24 h of residual effectiveness was observed from the two repellents when applied on cattle in the field. The limited residual effectiveness was correlated with the high volatility of the major active repellent compounds. CONCLUSION: All three natural product repellents effectively repel biting horn flies, exhibiting both feeding deterrence and spatial repellency. They may be used for developing an effective push-pull strategy with a slow release matrix that can prolong their effectiveness for horn fly management.