Traditional Morphometrics of Adult Mosquitoes

Summary

This protocol details a method for dissecting and measuring key morphological traits using an image analysis software to assess mosquito fitness.

Abstract

Mosquitoes are major vectors of pathogens that affect human and animal health. Measuring morphological traits of mosquitoes enables researchers to assess the impact of treatments (e.g., insecticide application, transgenesis) or ecological factors (e.g., nutritional stress, habitat changes) on fitness. Fitness in mosquito species has been linked to vectorial capacity, and thus directly impacts risk of vector-borne pathogen transmission. Here, we use an image analysis software to measure key morphological traits of mosquitoes collected during mosquito surveillance as a proxy for fitness.

Introduction

Fitness represents an individual organism’s capacity to survive and reproduce within its environment. Under ideal conditions, fitness research involves the assessment of environmental exposures on total reproductive capacity. However, measuring fecundity in ecological studies is often difficult, or even impossible, because the age of individuals in surveyed populations cannot be reliably controlled for. As such, ecologists measure functional traits, including morphological, physiological, and phenological traits, which have been shown to impact or be representative of an individual’s fitness^1,2. Su....

Protocol

NOTE: Insects are exempt from legal or institutional review board considerations. As such, no approval is necessary for this kind of research.

1. Mosquito dissection and imaging

1. Transfer individual wild-collected female mosquitoes into a 90 mm Petri dish and place them under a dissecting microscope equipped with a digital camera.
   NOTE: This protocol can be used for both lab-reared and wild-collected mosquitoes. Any known mosquito collection methods can be used with this dissection methodology.
2. Adjust the magnification based on the species and individual insect, and focus so that the entire body ....

Results

Our laboratory utilizes the described methodology in two ongoing ecological studies examining the impacts of habitat fragmentation on mosquito fitness and the impacts of socio-economic and socio-demographic factors on mosquito abundance, diversity, and fitness. At present, several hundred mosquitoes have been analyzed across both studies. Below are representative data from one of the habitat fragmentation studies, including measurements and analyses.

Following dissection, the side of the mosqu.......

Discussion

The methodology described here provides a means to assess mosquito morphological traits as a proxy for fitness. Such assessments are commonly used in ecological research on insects, birds, reptiles, and plants^{1,37,38,39,40,41}. Measuring key morphological traits allows researchers to conduct comparative ecology studies in the .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
100mm petri dish	Fischer Scientific	08-748C
Dissecting microscope with mounted camera	AmScope or similar	SM-4T-144S
Double-sided tape	3M	NC0879005
Fine tip forceps	Aven inc.	18059USA	Size 4 or 5, depending on preference
Image analysis software	AmScope or similar	SM-4T-144S	Many microscpe mounted cameras come with image analysis software. If none is available, free programs such as ImageJ can be used.
Micro scissors	Wexler Surgical	SL2000.1
Microscope slides	Fischer Scientific	12-544-4
Microscope Stage Calibration Slide	AmScope or similar	A36CALM1