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Simple Summary: The old-world sand fly, Phlebotomus papatasi (Scopoli 1786), is a major vector of Leishmania major, the predominant pathogen responsible for zoonotic cutaneous leishmaniasis in the Middle East, North Africa, Southern Europe, and Central Asia. DEET and other synthetic insect repellents have been used for personal protection against sand fly bites. However, the frequent use of DEET repellent raised concerns in regards to skin sensitivity, toxicity, and unpleasant odor. There are increasing efforts to evaluate natural products for use in developing more effective organic sand fly repellents. This paper reports the results of a laboratory study on several plant essential oils and saturated fatty acids concerning their repellency against female sand flies. A static air repellency assay was used to measure the responses of sand flies to test materials. The sand fly repellency of each test material was compared with those achieved by commercial repellent DEET and IR35353 at the same test concentration. The study identified two of the tested essential oils as effective spatial repellents at reduced concentrations compared to those of DEET, and two saturated fatty acids were found to produce significant sand fly mortality. The results from this study establish the foundation for developing more effective natural sand fly repellent products. The sand fly, Phlebotomus papatasi (Scopoli, 1786), is a major vector for Leishmania major in the Middle East, which has impacted human health and US military operations in the area, demonstrating the need to develop effective sand fly control and repellent options. Here, we report the results of spatial repellency and avoidance experiments in a static air olfactometer using the female P. papatasi testing essential oils of Lippia graveolens (Mexican oregano), Pimenta dioica (allspice), Amyris balsamifera (amyris), Nepeta cataria (catnip), Mentha piperita (peppermint), and Melaleuca alternifolia (tea tree); the 9–12 carbon saturated fatty acids (nonanoic acid, decanoic acid, undecanoic acid, and dodecanoic acid); and the synthetic repellents DEET and IR3535. The materials applied at 1% exhibited varying activity levels but were not significantly different in mean repellency and avoidance from DEET and IR3535, except in regards to nonanoic acid. Some materials, particularly nonanoic and undecanoic acids, produced sand fly mortality. The observed trends in mean repellency over exposure time included the following: (1) P. dioica oil, M. alternifolia oil, decanoic acid, undecanoic acid, DEET, and IR3535 exhibited increasing mean repellency over time; (2) oils of N. cataria, A. balsamifera, M. piperita, and dodecanoic acid exhibited relatively constant mean repellency over time; and (3) L. graveolens oil and nonanoic acid exhibited a general decrease in mean repellent activity over time. These studies identified the essential oils of N. cataria and A. balsamifera as effective spatial repellents at reduced concentrations compared to those of DEET. Additional research is required to elucidate the modes of action and potential synergism of repellents and essential oil components for enhanced repellency activity. [ABSTRACT FROM AUTHOR]

Screwworm flies are mass-reared and released along the Panama-Colombia border to prevent reinfestation of Central and North America. The cost of the production facility, labor, and diet materials makes mass-rearing the most expensive component of the program. The mass-rearing diet has a large impact on the quality and quantity of insects produced, both of which are necessary for the successful implementation of the sterile insect technique. The diet currently used to rear screwworm flies in Panama contains dried bovine red blood cells, dried bovine plasma, egg powder, milk replacement powder, cellulose (thickening agent), formaldehyde (antimicrobial), and water. Here, we tested an alternative diet containing 2 chicken by-products, which cost less and are locally available, to replace the egg powder and milk replacement powder currently used in the diet. We used 2 screwworm colony strains in our test, the current production strain (Jamaica) and an early female-lethal strain. The chicken diet performed similarly to the production diet with the Jamaica strain, while further optimization will likely be needed for transgenic strain. Finally, nutritional analysis conducted on 7 diet ingredients will assist with diet optimization and the identification of alternative diet ingredients. [ABSTRACT FROM AUTHOR]

Background: The cattle fever tick, Rhipicephalus (Boophilus) microplus, is a vector of pathogens causative of babesiosis and anaplasmosis, both highly lethal bovine diseases that affect cattle worldwide. In Ecdysozoa, neuropeptides and their G-protein-coupled receptors play a critical integrative role in the regulation of all physiological processes. However, the physiological activity of many neuropeptides is still unknown in ticks. Periviscerokinins (CAP2b/PVKs) are neuropeptides associated with myotropic and diuretic activities in insects. These peptides have been identified only in a few tick species, such as Ixodes ricinus, Ixodes scapularis and R. microplus, and their cognate receptor only characterized for the last two. Methods: Expression of the periviscerokinin receptor (Rhimi-CAP2bR) was investigated throughout the developmental stages of R. microplus and silenced by RNA interference (RNAi) in the females. In a first experiment, three double-stranded (ds) RNAs, named ds680-805, ds956-1109 and ds1102-1200, respectively, were tested in vivo. All three caused phenotypic effects, but only the last one was chosen for subsequent experiments. Resulting RNAi phenotypic variables were compared to those of negative controls, both non-injected and dsRNA beta-lactamase-injected ticks, and to positive controls injected with beta-actin dsRNA. Rhimi-CAP2bR silencing was verified by quantitative reverse-transcriptase PCR in whole females and dissected tissues. Results: Rhimi-CAP2bR transcript expression was detected throughout all developmental stages. Rhimi-CAP2bR silencing was associated with increased female mortality, decreased weight of surviving females and of egg masses, a delayed egg incubation period and decreased egg hatching (P < 0.05). Conclusions: CAP2b/PVKs appear to be associated with the regulation of female feeding, reproduction and survival. Since the Rhimi-CAP2bR loss of function was detrimental to females, the discovery of antagonistic molecules of the CAP2b/PVK signaling system should cause similar effects. Our results point to this signaling system as a promising target for tick control. [ABSTRACT FROM AUTHOR]

Potential reinvasion of the United States by cattle fever ticks, Rhipicephalus (Boophilus) annulatus (Say) and R. (B.) microplus (Canestrini), which are endemic in Mexico, threatens the domestic livestock industry because these ticks vector the causal agents (Babesia bovis (Babes) (Piroplasmida: Babesidae) and B. bigemina Smith & Kilborne) of bovine babesiosis. The Cattle Fever Tick Eradication Program safeguards the health of the national cattle herd preventing reemergence of bovine babesiosis by keeping the United States cattle fever tick-free. Free-living southern cattle tick, R. (B.) microplus, larvae have been collected from vegetation in the wildlife corridor of Cameron Co.- Willacy Co., Texas. Finding R. microplus larvae on vegetation complements reported infestations in wildlife hosts inhabiting the south Texas coastal plains. Substantial population expansion of native white-tailed deer Odocoileus virginianus (Zimmermann) (Artiodactyla: Cervidae), and exotic nilgai antelope Boselaphus tragocamelus (Pallas) (Artiodactyla: Bovidae), both of which are definitive hosts for the cattle fever tick, support local tick populations independent of cattle. Increasing prevalence of native and exotic wild ungulates, widespread tick acaracide resistance, and climate change, undermine efforts to control bovine babesiosis. Thus, ecological conditions have changed since cattle fever ticks were eradicated from the United States in 1943 using cattle-centric control strategies. These changes complicate efforts by the Cattle Fever Tick Eradication Program to keep cattle in the United States free of these cattle fever disease vectors. Technologies that could be applied to integrated eradication efforts are discussed. [ABSTRACT FROM AUTHOR]

Strains of Salmonella enterica can be subdivided into clades that differ in their genetic composition, influencing mi-crobial ecology and bacterial transmission. Salmonella serovar Montevideo strains 1110 and 304, representatives of two different clades, were used to evaluate interactions with the various stages of horn fly development. Sterilized cattle dung was inoculated with Salmonella monocultures, and horn fly larvae were exposed to 10³, 105, and 107 colony-forming units (CFU)/g per strain. Salmonella supported horn fly development, and concentration-dependent differences in pupal survival suggested that Salmonella Montevideo 304 impacts adult emergence when larvae are reared in a high concentration. Viable bacteria of each strain were quantified from larvae, pupae, and newly emerged adults. Both strains were cultured from larvae at a mean ~105, regardless of concentration, and both strains survived pupation. Quantities of Salmonella 1110 were stationary through the midpupal stage, after which quantities declined in pupae reared in 105 and increased twofold in pupae reared in 107 CFU/g. Quantities of Salmonella 304 remained stationary throughout pupal development when reared in 105, yet increased 29-fold when reared in 107 CFU/g. At high densities, properties of Salmonella 304 may influence its interaction with horn fly larvae, enabling the bacteria to evade degradation during larval gut histolysis and to subsequently proliferate during the late stages of pupal development. This may account for the observed effect on adult emergence. The Salmonella strains were rarely cultured from newly emerged adults, indicating that transstadial carriage to the adult stage is inefficient. [ABSTRACT FROM AUTHOR]