The horn fly, Haematobia irritans irritans (L.), is one of the most important external parasites of cattle in North America and elsewhere. Horn fly adults have an intimate association with cattle, their primary host. With their often-high numbers and by feeding up to 38 times per day per fly, horn flies stress cattle. The resulting productivity loss is valued at more than 2.3 billion USD in the United States. Insecticides are commonly used to mitigate direct injury from feeding and indirect injury from disease transmission. This paper discusses horn fly biology, distribution, and management. Emphasis is on promising new approaches in novel insecticides, repellents, biological control, vaccines, animal genetics, and sterile insect technology that will lead to effective preventative tactics and the integration of smart technologies with horn fly management. We conclude with a discussion of research needs necessary to shift horn fly integrated pest management to an emphasis on preventative tactics and the precision use of reactive techniques.
The effects of diet quality and temperature on the development time and size of stable flies, Stomoxys calcitrans (L.), was evaluated. Both development time and size varied relative to diet quality and temperature, and their effects were additive. Diet quality and temperature made similar contributions to the variance in size whereas temperature was responsible for >97% of the variance in development time. Regression analysis predicted the shortest development time, egg to adult, to be 12.7 days at 32 °C and 70% nutrients. Egg to adult development varied curvilinearly relative to diet quality and temperature on the degree day 10 (DD10) scale taking 261 DD10 at 30 °C and 50% nutrients. The thermal threshold was 11.5 °C with a thermal constant of 248. Very few stable flies developed to adult on the poorest diet (12.5% nutrients) and adults emerged from fewer than 1% of the puparia at 35 °C. The heaviest pupae (15.4 mg) were produced with the 100% diet at 15 °C and adults had a higher probability of emerging successfully from heavier puparia. The length of the discal-medial cell of adult wings had a cubic relationship with puparia weight and peaked at 21 °C. Egg to pupariation survival was predicted to peak at 27 °C and 71% diet whereas puparia to adult survival peaked at 24 °C and 100% diet. Diet quality and temperature had no effect on sex ratio and the rate of development did not differ between the sexes. Female stable flies were ≈5% larger than males. Composite metrics for egg to pupariation and egg to adult fitness were developed. The optimum for puparia fitness was 29 °C and 78% diet quality and for adult fitness 25 °C and 83% diet quality. Diet accounted for 31% of the variance in pupal fitness and 24% of the variance in adult fitness whereas temperature accounted for 17% and 20%, respectively.
Correction of “Gary J. Brewer, Dave J. Boxler, Luísa N. Domingues, Rebecca T. Trout Fryxell, Chris Holderman, Kelly M. Loftin, Erika Machtinger, Brandon Smythe, Justin L. Talley, and Wes Watson. 2021. Horn Fly (Diptera: Muscidae)—Biology, Management, and Future Research Directions. J. Integr. Pest Manag.”
In hybrid sunflower, bee pollination can improve productivity, but the contribution of bees to productivity may be over or underestimated. To estimate bee effects (seed trait gains from exposure to bees during anthesis), single capitula are commonly covered with a porous material to exclude bees. However, depending on the exclosure porosity, estimates of the magnitude of bee effects will vary. In two studies, porosity size and bee effect gains in two sunflower types were tested. In the exclosure study, Delnet exclosures severely reduced seed set and exclosures with larger porosities and had smaller and similar effects. However, since a few small bees penetrated the largest porosity size tested, exclosures with porosity sizes < 7 mm are recommended. With an exclosure porosity of 5 X 5 mm, the estimated bee effect contribution to the yield was 323 kg per hectare. Effects of exclosures on seed traits were similar in the oilseed and confectionary hybrids tested. Insecticide use did not affect seed traits but did lower insect damage to seeds. Bees from three families, mostly Apidae, were collected while foraging on sunflower. In summary, we recommend the use of exclosures with porosities of about 3 to 5 mm to avoid over or underestimating bee effects. And we recommend holistic insect management for sunflower cropping systems that balances the benefits of bee effects on seed traits with management of pest insects.
The sunflower midge, Contarinia schulzi Gagné, causes economic damage by inducing abnormal growth in infested heads (capitula) of sunflower, Helianthus annuus L. The primary objective of this study was to determine whether sunflower midge damage could be simulated and whether that simulated damage could be used to select midgetolerant sunflower germplasm. An additional objective was to develop a quantitative alternative to the scoring systems used to visually estimate damage. Sunflower plants were treated by injecting buds with the synthetic auxin 2,4-dichlorophenoxy acetic acid (2,4-D), which resulted in a distortion of the head morphology that was similar in appearance to the damage caused by the sunflower midge. The extent of distortion depended not only on the dose of 2,4-D but also on the size and growth stage of the head when injected. Among sunflower hybrids tested, resistance to the sunflower midge was significantly, negatively correlated with 2,4-D damage. Therefore, injection of sunflower heads with 2,4-D appears to be an effective method of screening sunflower germplasm for tolerance to the sunflower midge. Two distortion indices, based on measurements of head shape, were compared with the visual damage system. Although the visual rating system is faster, distortion index 2 gave similar results and is preferred when it is necessary to avoid individual differences in scoring techniques.