Nectar-related vs. human-related volatiles: behavioural response and choice by female and male Anopheles gambiae (Diptera: Culicidae) between emergence and first feeding

Abstract

The close association of Anopheles gambiae Giles with humans and its females' ability to live on human blood alone suggest that females may ignore sources of sugar in favour of human blood as a source of energy. They have limited energy reserves at emergence, and at 27°C both sexes generally die if they do not feed during night 1, 24-36 h after emergence. Food preferences during this critical period were tested by measuring responses to volatiles from honey and soiled socks, which served as surrogates for nectar-related and human-related volatiles in a wind-tunnel olfactometer. Both sexes responded more strongly to honey than to human volatiles, and given a choice, preferred honey over human volatiles. After 5 days of sugar access and maturation, males continued to prefer honey volatiles, whereas females changed behaviour, responding almost exclusively to human volatiles. Night 1 experiments also demonstrated that: (i) females previously having had sugar during the night of emergence responded more strongly to human volatiles; (ii) large-bodied mosquitoes of both sexes responded more strongly to honey than small-bodied ones; and (iii) females were equally responsive to honey in both early and late scotophase but were slightly more responsive to human volatiles in late scotophase. These results indicate that for a female's first meal, sugar is a viable option and is preferred when nectar-related stimuli are strong. This supports field evidence that sugar-feeding is a significant component of A. gambiae female behaviour.

Effects of Plant-Community Composition on the Vectorial Capacity and Fitness of the Malaria Mosquito Anopheles gambiae

“…For instance, when sugar is readily available, young female An. gambiae may prefer to feed on sugar, 21 whereas when sugar is restricted and/or blood hosts are readily available even young females may seek a blood meal. 22,23 Thus, the age at which mosquitoes obtain their first blood meal may depend on environmental access to sugar.…”

The sugar meal of the African malaria mosquito Anopheles gambiae (Giles) and how deterrent compounds interfere with it: a behavioural and neurophysiological study

“…To date, the physiological basis in A. gambiae for discriminating between plant species is still unknown. At medium to long range, plant volatiles probably inform mosquitoes of the presence of a sugar source (Foster and Takken, 2004) as well as those of unsuitable plants, as shown by the strong repellent activity of some plant extracts against female A. gambiae searching for a host (Odalo et al, 2005). After landing on the plant, mosquitoes use terminal pore sensilla on their legs and mouthparts to find the nectar source (Pappas and Larsen, 1978) and probably to taste meal quality, such as the sugar concentration or the presence of toxic and unpalatable substances.…”

Using bacteria to express and display anti-parasite molecules in mosquitoes: current and future strategies

“…By placing sucrose sources spiked with the engineered bacteria in or around residences, mosquitoes would be repeatedly exposed to the bacteria. The effectiveness of this bait station may be improved if attractants, such as key components of nectar, are added to the bait (Foster and Takken, 2004). A potential drawback to this approach is the exposure of non-target arthropods, which may also feed at the bait station, to the engineered bacteria.…”