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Predatory Potential of Nymphal Odonates on Aedes aegypti Developing in Freshwater and Brackish Water Habitats
by
, and
Sivasingham Arthiyan
1,*,
Thampoe Eswaramohan
1,
Andrew Hemphill
2 and
Sinnathamby Noble Surendran
1
1
Centre for Research in Entomology (CRE), Department of Zoology, Faculty of Science, University of Jaffna, Jaffna 40000, Sri Lanka
2
Institute of Parasitology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
*
Author to whom correspondence should be addressed.
Insects 2024, 15(7), 547; https://doi.org/10.3390/insects15070547
Submission received: 24 June 2024
/
Revised: 15 July 2024
/
Accepted: 16 July 2024
/
Published: 19 July 2024
(This article belongs to the Section Medical and Livestock Entomology)
Simple Summary
Simple Summary: Aedes aegypti, the primary vector of dengue, undergoes preimaginal development in freshwater and brackish water habitats in northern Sri Lanka and other parts of the world. Dengue vector control in the form of source reduction targets only freshwater habitats. Since biological control is a component of integrated vector control, the present study investigated the predatory efficacy of dragonfly nymphs and damselfly nymphs that develop in both freshwater and brackish water habitats targeting Ae. aegypti larval forms in laboratory conditions. The dragonfly nymph Hydrobasileus croceus and the damselfly nymph Paracercion hieroglyphicum were found to be the most effective among six different species tested in both freshwater and brackish water conditions. The findings suggest that these odonate nymphs could serve as biological control agents to target preimaginal forms of dengue vectors under varying salinity conditions.
Abstract
Aedes aegypti, the primary vector of dengue, undergoes preimaginal development in brackish water (BW). However, dengue vector control exclusively targets freshwater (FW) habitats. The present study evaluated the predatory efficacy of nymphal odonates that can develop in both FW and BW. Nymphs of three damselfly and three dragonfly species from FW and BW habitats were identified and acclimatized to FW (<0.5 gL−1 salt) and BW (10 gL−1 salt) mesocosm conditions. The experiment was repeated nine times with nine different individual predators per species under both salinity conditions. One hundred L3 Ae. aegypti from FW and BW laboratory colonies were introduced to determine the predatory rate (PR) and clearance rate (CR) after 24, 48, and 72 h, and one hundred L3 larvae were introduced every 24 h. The dragonfly nymph Hydrobasileus croceus and the damselfly nymph Paracercion hieroglyphicum showed the highest PR and CR under both rearing conditions at all times. However, damselfly and dragonfly nymphs significantly (p < 0.05) differed in their CR under both FW and BW conditions. Thus, all six odonate species have predatory potential and this suggests that they could be used as biological control agents to eliminate preimaginal stages of Ae. aegypti developing in both FW and BW habitats.
