Size of Openings in Water-Holding Containers: Impact on Oviposition by Culex (Culex) Mosquitoes

Abstract

To assess how a grate covering a catch basin impacts oviposition by Culex mosquitoes, a field study was conducted in south Florida using containers with two types of covers, with openings of equal area, but different configurations. One opening mimicked a catch basin grate with 16 small openings, while the other cover had just one large opening. The number and presence of egg rafts in six of each container and cover combination was recorded over 18 nights at two field sites, consisting of a wastewater management facility area and residential subdivision. Three mosquito species, all belonging to the subgenus Culex accounted for more than 99% of total egg rafts collected: Culex nigripalpus (n = 1766), Culex quinquefasciatus (n = 754) and Culex coronator (n = 526). Approximately 90% of Cx. nigripalpus and Cx. coronator egg rafts were deposited in the containers with the large opening cover; whereas more Cx. quinquefasciatus egg rafts were laid in the containers with small opening covers than those of Culex nigripalpus and Culex coronator combined. Similar patterns of egg laying activity were noted at each sampling stations. These results suggest that for locating oviposition sites Culex quinquefasciatus may rely more on olfactory clues, while other Culex species depend more on visual clues.

The Goldilocks principle: Finding the balance between water volume and nutrients for ovipositing Culex mosquitoes (Diptera: Culicidae)

“…Color of the container habitat has been shown to impact oviposition choice among female mosquitoes with females preferring darker-colored containers [ 41 ]. In this project, all the containers were white, which may have impacted the results of the study as Culex females may be using the visual cue of the water height in relationship to the exposed height of the white container as a way to determine suitable habitats for their offspring [ 42 ]. Two major limitations of this study was that the height of the water to the top of the container and water depth was not fixed but varied with water volume with smaller volumes of water being lower in the container habitat and having a smaller depth of water and larger volumes of water coming closer to the top of the container and having a greater depth of water.…”

Coagulation-Flocculation: A potential Application for Mosquito Larval Source Management (LSM) with No Insecticide Resistance

“…In the experiment, female mosquitoes laying eggs in two cups (d = 11 cm, h = 5 cm, transparent plastic material) were considered as valid oviposition. After each biting, all of the eggs laid by one single female Culex pipiens pallens would gather together as an egg raft and oat on the water [35], thus we can recognize the number of valid oviposition times easily. Each observation and removal of all mosquito eggs in O1 & O2 is considered as an independent observation.…”