Investigation of Cuticular Hydrocarbons for Determining the Age and Survivorship of Australasian Mosquitoes

Abstract

The cuticular hydrocarbon (CH) technique of age grading mosquitoes was evaluated for use on laboratory-reared Aedes aegypti (L.), Anopheles farauti (Laveran), and Ochlerotatus vigilax (Skuse). Gas chromatography/mass spectroscopy was used to determine the relative abundance of five alkanes in hexane extracts from the legs of individual mosquitoes. Age-related changes to relative hydrocarbon abundances were observed from An. farauti and Ae. aegypti, which are vectors of malaria and dengue, respectively. Female An. farauti were classified into two age categories (1-5 and >/= 5 days old at 27 degrees C) and Ae. aegypti into three age categories (1 to < 5, 5 to < 9 and >/= 9 days old at 27 degrees C) based on these changes. However, there was an absence of predicable age-related changes to hydrocarbon abundance in Oc. vigilax. Simulation modeling was used to construct sequential sampling guidelines for the application of this technique to estimate the survivorship of Ae. aegypti and An. farauti populations. These guidelines define the relationship between the survival rate, number of mosquitoes sampled, CH-based predictions of age, and the accuracy of survival rate estimates. They demonstrated, for example, that if 19% of a population of Ae. aegypti is estimated to be >/= 9 days old by CH analysis, an estimate of the daily survival rate from the exponential model should be based on a sample of 200 mosquitoes for the survival rate estimate to be within 5% of the actual rate. However, if only 10% of the population is estimated to be >/= 9 days old, 500 mosquitoes would need to be analyzed for the survival rate estimate to be of equivalent accuracy.

Non-destructive Determination of Age and Species of Anopheles gambiae s.l. Using Near-infrared Spectroscopy

“…Using cuticular hydrocarbons to age-grade mosquitoes also results in difficulty in classifying seven-day-old mosquitoes into an old or young age group. 58 Lipids and glycogen have been shown to change in male mosquitoes as they age. 59 Peaks in Figure 6 at approximately 1,221, 1,412, and 1,728 nm correspond to absorption by lipids, and thus may contribute to our classification models.…”

The use of transcriptional profiles to predict adult mosquito age under field conditions

“…CHCs were extracted from all legs of individual field-reared mosquitoes and quantified by GC-MS based on methods described in Hugo et al (36). Peak areas of four CHC measures of interest (C 25 H 52 , C 26 H 54 , C 27 H 56 , and C 28 H 58 ) and a reference measure (C 29 H 60 ) were quantified.…”

Comparative analysis of epicuticular lipid profiles of sympatric and allopatric field populations of Anopheles gambiae s.s. molecular forms and An. arabiensis from Burkina Faso (West Africa)

“…Age-related variations have been shown in females of Ae. aegypti (Desena et al, 1999a, b, Horne andPriestman, 2002;Polerstock et al, 2002;Gerade et al, 2004, Hugo et al, 2006, Culex quinquefasciatus (Chen et al, 1990), An. gambiae (Polerstock et al, 2002;Caputo et al, 2005), An.…”

“…stephensi (Brei et al, 2004) and An. farauti (Hugo et al, 2006). Epicuticular lipids have also been investigated as taxonomic characters in several insect taxa, including mosquito species complexes.…”