RESEARCH POSTER PRESENTATION DESIGN © 2012

www.PosterPresentations.comRESEARCH POSTER PRESENTATION DESIGN © 2019

www.PosterPresentations.com

Intraguild predation by mosquito (Diptera: Culicidae)

larvae is widespread across the taxa, confirmed in at least

thirteen genera1–9. The manifestation of this behavior is

however vastly diverse in the following aspects:

dependency on predation (facultative or obligate), prey-

catching mechanisms along with associated morphology,

and prey selection (intraspecific or interspecific). In this

study the occurrence of interspecific predation and

cannibalism (intraspecific predation) is investigated in

order to fully describe unique voracious behavior within

the Neotropic species Sabethes cyaneus and yellow fever

vector Sa. chloropterus10.

INTRODUCTION

The Sabethes spp. larvae used in the study were from

colonies originally established by R. G. Hancock and W.

A. Foster from mated females collected from Isla Majé,

Lago Bayano Panamá in 1988. These colonies as well as

Aedes aegypti and Ae. albopictus (prey) colonies have

been housed and maintained at Metropolitan State

University of Denver at 27 ± 1 °C with a 12:12 light:dark

cycle. Larvae for the experiments described below were

reared in plastic trays filled with aged tap water and fed

powdered Tetramin® twice weekly.

To assess the occurrence and frequency of interspecific

and intraspecific predation, Sabethes larvae were isolated

from recently fed trays and placed individually into a (3.3

cm2) cell of a silicone ice tray filled with aged tap water. A

potential prey larva (instars of the same species, a species

within the same genus, or a different genus- Aedes) was

then added to each occupied cell. Observations were

recorded every 24hr for up to 72hr.

To further document the possible occurrence of

cannibalism and fully elucidate the prey-catch mechanism

by sabethine larvae, high-speed microvideography was

used. Recordings at 180 frames per second (fps) were

made using Panasonic Lumix GH5 cameras fitted with

macro lenses including an Infinity Optical Robusto system

(Infinity Optical Company, Boulder, CO). Recordings of

500-1200fps were made using a Ximea (Münster,

Germany) XiQ USB 3.0 Superspeed camera (model

M0013cG-ON) fitted with a Kern Switar 75mm c-mount

Macro lens.

The range of the predatory strike was investigated in 15-

minute overhead recordings of trials during which six 4th

instar Sa. cyaneus and Sa. chloropterus respectively were

paired against a 1st or 2nd instar Ae. aegypti. Trials were

conducted in silicone ice trays. Mean distance to prey was

compared using one-way anova and the Turkey-Kramer

test.

MATERIALS & METHODS

Sa. cyaneus and Sa. chloropterus were observed to have essentially identical predation mechanics. Initiation occurs

predominately from one of two positions: surfaced (respiring) or lying on the bottom of the container. In both instances, the

dorsa is normally facing the nearest surface as larvae appear to overwhelmingly prefer positions close to the walls of the

container (Figure 1a). Once prey is detected the maxillae flare (Figure 1b) right before both the anterior and posterior parts of

the body are thrust towards the prey at a high speed. During this action the sclerotized siphon strikes the prey, bringing it

directly to the mouth, between the maxillae, and once secure the predator clamps down (Figure 1c). This entire action occurs

within approximately 16 milliseconds. The predator customarily thrashes the caught prey violently from side to side with

quick motions of its head, sometimes even resecuring the position of the prey between the mandibles using its siphon. Prey

consumption, which is typically incomplete in this species, involves the action of teeth on the mandibles, which cut into held

prey (Figure 1d).

CONCLUSIONS

Both Sa. cyaneus and Sa. chloropterus were observed

preying on Ae. aegypti and Ae. albopictus. Mean strike

distance between species was significantly heterogeneous

(Turkey-Kramer test, P>0.05). Cannibalism was readily

observed within Sa. chloropterus even without starvation

of the larvae. However, results are inconclusive on

whether Sa. cyaneus cannibalize. We suspect the behavior

in this species may be only prevalent in response to

starvation as seen in other species such as Culex pipens7

however further data is needed to confirm . Other

preliminary results allude to the presence of interspecific

predation by 4th instar Sa. chloropterus on younger 2nd/3rd

Sa. cyaneus and a lack of predation when the roles are

reversed. Both Neotropic species utilize the unique

siphon-strike to capture their prey.

REFERENCES1.Pramanik, S., Banerjee, S., Banerjee, S., Saha, G. K. & Aditya, G. Observations on the predatory

potential of Lutzia fuscana on Aedes aegypti larvae: Implications for biological control (Diptera:

Culicidae). Fragm. Entomol. 48, 137–142 (2016).

2.Lounibos, L. P. BEHAVIORAL CONVERGENCES AMONG FRUIT-HUSK MOSQUITOES.

Florida Entomol. 66, 32–41 (1983).

3.Ratsirarson, J. & Silander, J. A. Structure and Dynamics in Nepenthes madagascariensis Pitcher

Plant Micro-Communities. Biotropica 28, 218–227 (1996).

4.Mogi, M. & Chan, K. L. Predatory habits of dipteran larvae inhabiting Nepenthes pitchers.

Raffles Bull. Zool. 44, 233–245 (1996).

5.Digma, J. R., Sumalde, A. C. & Salibay, C. C. Laboratory evaluation of predation of

Toxorhynchites amboinensis (Diptera:Culicidae) on three mosquito vectors of arboviruses in the

Philippines. Biol. Control 137, 104009 (2019).

6.Koenraadt, C. J. M. & Takken, W. Cannibalism and predation among larvae of the Anopheles

gambiae complex. Med. Vet. Entomol. 17, 61–66 (2003).

7.El Husseiny, I., Elbrense, H., Roeder, T. & El Kholy, S. Hormonal modulation of cannibalistic

behaviors in mosquito (Culex pipiens) larvae. J. Insect Physiol. 109, 144–148 (2018).

8.Dennehy, J., Robakiewicz, P. & Livdahl, T. Nordic Society Oikos Larval Rearing Conditions

Affect Kin-Mediated Cannibalism in a Treehole Mosquito.No Title. Oikos 95, (2001).

9.Mastrantonio, V. Cannibalism in temporary waters: Simulations and laboratory experiments

revealed the role of spatial shape in the mosquito Aedes albopictus. PLoS One 13, 1–12 (2018).

10.DE RODANICHE, E. & GALINDO, P. Isolation of Yellow Fever Virus from Haemagogus

Mesodentatus, H. Equinus and Sabethes Chloropterus Captured in Guatemala in 1956. Am. J. Trop.

Med. Hyg. 6, 232–237 (1957).

11.Ralph E. Harbach. Ontogeny of the Larval Stage of Sabethes Chloropterus With Special

Reference to Setal Development and Phylogenetic Implications for the Family Culicidae (Diptera).

Mosquito Systematics vol. 23.

ACKNOWLEDGEMENTS

Metropolitan State University of Denver

Taylor Boyd, Shannon MacFadden, and Robert Hancock PhD

Larval violence in Neotropical jungle mosquitoes: investigations of interspecific predation mechanics in two sabethine mosquitoes

Fig. 1. Depiction of predation mechanics of Sa. chloropterus on Ae. aegypti over one second. 1a. Larva filter-feeding, maxillae tucked in. 1b. Pre-strike position,

maxillae flared. 1c. Post-strike siphon-capture. 1d. Prey consumption.

RESULTS

Fig. 2. Mean prey distance (dashed lines) and 95% confidence regions (dotted

lines) for successful siphon-strikes of Sa. chloropterus (left) and Sa. cyaneus (right)

larvae. The means were significantly heterogeneous (one-way anova, F1,39 =8.882,

P=0.0049; Turkey-Kramer test, P>0.05)

1,000 milliseconds16ms

1a. 1b. 1c. 1b.

1a. 1b. 1c. 1d.1c.

1c.

Sa. cyaneus adult by K. Custer 2020 Sa. chloropterus adult by R. G. Hancock 1991

Special thanks to Woodbridge A. Foster, PhD for providing the original Sa.

cyaneus and Sa. chloropterus colonies used in this study. Thanks to Shawn Ward

and Connor O’Brien-Stoffa for their role in rearing and maintenance of the

colonies as well as Johnathan Dyhr, PhD for his assistance in high-speed

filming.

Contact: tboyd12@msudenver.edu; smacfadd@msudenver.edu

Fig. 3. Developmental changes from the 1st to 4th instar of Sa.

chloropterus larvae. I. 1st instar with unsclerotized siphon and relatively

underdeveloped mouthparts. II. 2nd instar, during this stage siphon will

completely sclerotize, development of sensory structures (setae, posterior

filaments) on anterior. III. & IV. 3rd and 4th instars respectively, size

increases dramatically, setae branch out11.

Sa. chloropterus was observed predating as early as the second

instar. This development in behavior coincides with the

development of both the maxillae and the siphon (See Figure

3). In this instar the terminal hook-like projection and lateral

teeth of the maxillae take form. The siphon also advances

within this stage and is now fully sclerotized, longer, and

equipped with setae and a posterior row of filaments11.