The life history and mosquito consumption dynamics of Notonecta indica (Hemiptera: Notonectidae) in eastern Jamaica

Abstract

Certain mosquito species pose a significant threat to human health, causing thousands of deaths annually via diseases such as yellow fever, dengue fever, and chikungunya. A variety of insects, including dragonflies and backswimmers, prey on mosquito larvae, providing natural population suppression, but knowledge of the life history and quantification of the mosquito suppression dynamics of these insects remain limited in the Caribbean. In the present study, we documented aspects of the life history of the backswimmer Notonecta indica L. in Jamaica and quantified its consumption of Aedes aegypti (L.) larvae throughout development and at different mosquito densities. The egg and fifth nymphal stages had the longest mean development times while the third nymphal stage had the shortest. Development was noted to be shorter in N. indica when compared to other backswimmer species from different climates, likely due to higher temperatures and greater food availability in the present study. Daily mosquito consumption increased exponentially throughout nymphal development. Individual adults displayed significant variation in daily mosquito consumption, and consumption was found to be directly proportional to mosquito density. Backswimmers may contribute to mosquito suppression and the reduction of mosquito-borne diseases, but their contribution is likely limited by the spatial and temporal differences between backswimmers and mosquitoes, namely, in habitat preferences, dispersal patterns, and development times.

Keywords: backswimmer; density; development; oviposition; predator.

Fig. 1.

Categories of daily egg production among Notonecta indica adults from Jamaica. Data from F0_M, F1_M, and F0_H cohorts. n = 101.

Fig. 2.

Number of eggs produced daily by backswimmers from Mona (M) and Hellshire (H) across their oviposition periods. Data from F0_M, F1_M, and F0_H.

Fig. 3.

The life stages of Notonecta indica in Jamaica. Images are not to scale. A) Eggs within 24 h of oviposition. B) Egg 4 days after oviposition showing red eye spot. C) Eggs 6–7 days after oviposition with body features becoming defined. D) Upper—Empty egg case, lower—egg (with anterior swelling) which failed to hatch. E) Two first instar nymphs consuming an L4 mosquito larvae. F) Fourth instar nymph emerging from third instar exuvium (< 24 h after molting). G) Fourth instar nymph > 24 h after molting. H) Dorsal view of adult < 24 h after emergence. I) Dorsal view of adult > 24 h after emergence. J) Ventral view of adult > 24 h after emergence.

Fig. 4.

Correlation of body length at each life stage between Notonecta indica and 4 other backswimmer species.

Fig. 5.

Age-specific A) and stage-specific B) survival rate of a cohort of Notonecta indica in Jamaica. Data from F1_M. n_x in N1 = 107, n_x in N2 = 60, n_x in N3 = 35, n_x in N4 = 19, n_x in N5 = 11, n_x in adulthood = 7.

Fig. 6.

Mean daily mosquito consumption by Notonecta indica among ages A) and life stages and ages B). Data from F0_M. Density = 100 larvae per treatment. n = 191, number of backswimmers = 15. Errors bars represent standard error.

Fig. 7.

Mean daily mosquito consumption among Notonecta indica adults. Data from F0_M, F1_M, and H0_M. Density = 100 larvae per treatment. n = 5 for each backswimmer. Errors bars represent standard error.

Fig. 8.

Mean daily consumption A) and percentage consumption B) of mosquitoes by Notonecta indica at 5 mosquito densities in Jamaica. Data from F0_M and F1_M. n = 6 for 50-larvae density, n = 12 for all other densities. Errors bars represent standard error.

Fig. 9.

Mean daily consumption A) and percentage consumption B) of mosquitoes by single (SB) and paired (PB) Notonecta indica adults at the 100- and 400-larvae densities. Data from F0_M and F1_M. n = 9 for all control treatments, n = 16 for the 100-larvae density for single and paired treatments, n = 3 at the 400-larvae density for single and paired treatments. Errors bars represent standard error.