approach for mosquito control. Further understanding of the molecular mechanisms involved would help identify additional novel targets for vector control using ATSB.

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Mosquitoes have distinct developmental and adult life history, and the vectorial capacity of females has been shown to be affected by the larval nutritional environment. However, little is known about the effect of developmental nutrition on insulin-signaling and nutrient storage. In this study, we used Aedes aegypti, the yellow fever mosquito, to determine whether larval nutrition affects insulin gene expression. We also determined the traits regulated by insulin signaling, such as stored-nutrient levels and fecundity. We raised mosquito larvae on two different diets, containing either high protein or high carbohydrates. Development on a high-carbohydrate diet resulted in several life-history phenotypes indicative of suboptimal conditions, including increased developmental time and decreased fecundity. Additionally, our data showed that insulin transcript levels are affected by a high-carbohydrate diet during development. Females, not males, reared on high-carbohydrate diets had much higher transcript levels of insulin-like peptide 3 (ILP3), a mosquito equivalent of human insulin, and these females more readily converted sugar meals into lipids. We also found that AaILP4, not AaILP3, transcript levels were much higher in the males after a sugar meal, suggesting sex-specific differences in the insulin-signaling pathway. Our findings suggest a conserved mechanism of carbohydrate-mediated hyperinsulinemia in animals.

Lyme disease is the most important vector-borne disease in the United States and is increasing in incidence and geographic range. In the Pacific west, the western black-legged tick, Ixodes pacificus Cooley and Kohls, 1943 is an important vector of the causative agent of Lyme disease, the spirochete, Borrelia burgdorferi. Ixodes pacificus life cycle is expected to be more than a year long, and all three stages (larva, nymph, and adult) overlap in spring. The optimal habitat consists of forest cover, cooler temperatures, and annual precipitation in the range of 200–500 mm. Therefore, the coastal areas of California, Oregon, and Washington are well suited for these ticks. Immature stages commonly parasitize Western fence lizards (Sceloporus occidentalis) and gray squirrels (Sciurus griseus), while adults often feed on deer mice (Peromyscus maniculatus) and black-tailed deer (Odocoileus h. columbianus). Ixodes pacificus carry several pathogens of human significance, such as Borrelia burgdorferi, Bartonella, and Rickettsiales. These pathogens are maintained in the environment by many hosts, including small mammals, birds, livestock, and domestic animals. Although a great deal of work has been carried out on Ixodes ticks and the pathogens they transmit, understanding I. pacificus ecology outside California still lags. Additionally, the dynamic vector–host–pathogen system means that new factors will continue to arise and shift the epidemiological patterns within specific areas. Here, we review the ecology of I. pacificus and the pathogens this tick is known to carry to identify gaps in our knowledge.

Ixodes scapularis is the major vector of Lyme disease in the Eastern United States. Each active life stage (larva, nymph, and adult) takes a blood meal either for developing and molting to the next stage (larvae and nymphs) or for oviposition (adult females). This protein-rich blood meal is the only food taken by Ixodes ticks and therefore efficient blood digestion is critical for survival. Studies in partially engorged ticks have shown that the initial stages of digestion are carried out by cathepsin proteases within acidic digestive cells. In this study, we investigated the potential role of serine proteases in blood digestion in replete ticks. RNA interference was used for functional analysis and a trypsin-benzoyl-D, L-arginine 4-nitoanilide assay was used to measure active trypsin levels. Hemoglobinolytic activity was determined in vitro, with or without a serine protease inhibitor. Our data suggest that trypsin levels increase significantly after repletion. Knockdown of serine proteases negatively impacted blood feeding, survival, fecundity, levels of active trypsin in the midgut, and resulted in lower hemoglobin degradation. Incubation of midgut extract with a trypsin inhibitor resulted in 65% lower hemoglobin degradation. We provide evidence of the serine proteases as digestive enzymes in fully engorged, replete females. Understanding the digestive profile of trypsin during blood meal digestion in I. scapularis improves our understanding of the basic biology of ticks and may lead to new methods for tick control.