The applicability of spectrophotometry for the assessment of blood meal volume inartificially fed Culicoides imicola in South Africa

Abstract

. The volume of the blood meal of haematophagous insects will determine the number of infective particles taken up during feeding and may as such denote the minimum dose needed to infect a competent vector. Culicoides midges resort among the smallest of haematophagous vectors and determining and comparing their blood meal volumes may be challenging. Collected Culicoides imicola females were fed on defibrinated bovine blood through a Parafilm® membrane using a Hemotek® system. After feeding, the weight of pools of 10 engorged females was compared to that of 10 unfed females to determine the volume of blood imbibed. After weighing, the pools were homogenized and their absorbance read at 410 nm. Spectrophotometer readings were then converted to blood meal volumes using calibration curves, obtained by the dilution of known volumes of blood used for feeding. Although the mean blood meal volumes determined spectrophotometrically (0.06 μL), differed significantly (P < 0.01) from those obtained by weighing (0.07 μL), the range in blood meal volumes determined spectrophotometrically (0.03–0.08 μL) and by weighing (0.01–0.11 μL) was positively correlated (r = 0.7; P < 0.01). Both methods can be used to determine the blood meal volume.

Impacts of Infectious Dose, Feeding Behavior, and Age of Culicoides sonorensis Biting Midges on Infection Dynamics of Vesicular Stomatitis Virus

“…Estimating that C. sonorensis midges ingest a volume of 100–150 nL [ 20 , 21 ], feeding events on blood meals with titers lower than 5 log 10 PFU/mL may result in fewer than one virion being ingested, lowering the chance that midges will become infected. A previous study with intrathoracic injections of C. sonorensis midges with 200 nL volumes of bluetongue virus at 3 log 10 PFU/mL resulted in only 35% of midges becoming infected [ 45 ].…”

“…Vesicular lesions and saliva contain high, measurable virus titers, and contaminate skin surfaces where midges pool-feed [ 19 ]. For VSV acquisition, midges must feed on infected hosts that are shedding virus at titers high enough to be taken up in their 100–150 nL volume blood meal (BM) [ 20 , 21 ]. Ingested virus must survive the digestive environment of the midgut, infect the midgut epithelium, and result in progeny virus crossing the basal lamina layer to disseminate into the hemolymph and subsequently infect and replicate in surrounding tissues, including the salivary glands.…”

Effect of Constant Temperatures on Culicoides sonorensis Midge Physiology and Vesicular Stomatitis Virus Infection

“…Females from many Culicoides species blood-feed in swarms on a wide variety of vertebrate hosts but feed preferentially on domestic and wild ruminants and horses [34,35]. While taking small blood meals [36,37], the success of midges as vectors is primarily due to large population sizes that can be sustained with suitable climatic conditions [1]. Under standard laboratory conditions (25 • C and 70% RH), adult C. sonorensis females can complete three to four gonotrophic cycles (GC) within their three-to six-week lifetime [38].…”

Modelling High-Risk Areas for African Horse Sickness Occurrence in Mainland China Along Southeast Asia

“…The horse density was positively correlated with the AHS occurrence (Riddin, Venter, Labuschagne, & Villet, 2019); other studies (Bakhoum et al, 2016;Fall et al, 2015;Garros et al, 2011) also showed the very complex relationship between the AHS vectors and livestock. Female Culicoides depend mostly on blood meals as a food source (de Beer, Boikanyo, Venter, & Mans, 2020;Slama, Haouas, Mezhoud, Babba, & Chaker, 2015). In dense urban and built-up areas, where the urban population and livestock sector is continually expanding, the transmission probability of AHS may be greatly increased.…”