Nutrition and senses in D. suzukii larvae

Nutrition and senses in D. suzukii larvae

MSC-IF Project

In this space I will tell you about my current research project about the nutritional and sensory adaptations of the larva of D. suzukii flies. It is generously financed by a Marie Sklodowska-Curie (MSC) Individual Fellowship from the European Comission.

Last year I started working as a Postdoc at the Department of Evolutionary Neuroethology of the Max Planck Institute for Chemical Ecology in Jena, Germany, under the supervision of Dr. Bill Hansson and Dr. Markus Knaden, and since this year I started my new project,

So from now on, apart from updating sci-flies.com to continue exploring the history of Drosophila flies as a model organism and the research scientists do with it, I will also tell you about the progress of my own research.

The conquest of a new habitat: a study of nutritional and sensory adaptations in Drosophila suzukii larvae

Introduction

Animals need NUTRIENTS

Animals eat to incorporate nutrients -proteins, sugars and lipids- from the environment. They need those nutrients both as a source of energy, and as material to grow and maintain their bodies.

During the life cycle of the fly, we can recognize two very different forms of the animal with very different objectives and needs for nutrients. The larva eats to grow and store reserves for metamorphosis. The adult needs energy to reproduce, which means flying to find a mate, courting, copulating, producing eggs and finding a place to lay those eggs.

FOODS HAVE DIFFERENT NUTRITIONAL VALUE

Not all foods are the same. Some may have more protein, some may be more sugary and others more fatty. Depending on the needs of the animal, foods with different compositions may have a higher or lower nutritional value to them.

Food sources can have a dynamic composition. Ripe fruits have usually a high sugar content in relation to protein. When fruits are overripe and start rotting, their protein content is higher and their sugar content lower. They may be preferred by different animal species.

ANIMALS JUDGE FOODS AND THEIR NEEDS

Animals have to search their environment to find the food they need. To be able to find and choose their food in the best way possible, animals have mechanisms that allow them to determine what they need and mechanisms to judge the nutritional value of food.

Before they eat something, they can use their senses of smell and taste, to perceive chemicals from the food that tell them of the possible presence of specific nutrients in it.

They also have mechanisms to sense their internal state that let them know, through signals between their organs and their brain, if the food they already ate was good enough or not.

DIFFERENT SPECIES HAVE DIFFERENT NEEDS

As the result of their individually unique evolutionary histories, different animal species have taken up different roles in their environment, what we call “to occupy different ecological niches”. This means that each species may have particular nutritional needs and particular food preferences.

My Question

With my project, I would like to understand how are the mechanisms for sensing the nutritional value of food tuned to the needs of a species, according to the role the species occupies in its environment and its evolutionary history.

Are the sensing mechanisms of different species adapted to their specific dietary needs?

My approach

Through this question I want to place the study of how animals evaluate the nutritional value of foods in the context of their evolution and ecology.

This implies a comparative study of the mechanisms for food nutritional value evaluation of different fly species (the evolutionary aspect) against the nutritional composition of their natural feeding substrates (the ecological aspect).

The specifics of my project

The adult female of Drosophila melanogaster (our beloved model organism), lays her eggs on overripe or rotting fruits. These fruits are full of yeasts and have a high protein content. The larvae then develop and grow on a proteinic diet.

On the other hand, the adult female of the spotted-wing fly (Drosophila suzukii) have a specialized ovipositor (the part of their genitals that holds and lays the egg), bigger and with denticles, that can pierce the hard skin of some fruits (berries and the like).

The ovipositor allowed D. suzukii to conquer a new niche, since no other Drosophila species can lay eggs through the skin of fresh fruits.

D. suzukii flies prefer to lay eggs on undamaged, ripening fruit, still on the plant. Fresh fruits are not yeasty, they have less protein and are more sugary.

This way during their larval period, when growth and weight gain occurs, D. suzukii flies and D. melanogaster flies feed on substrates of very different composition.

My Objective

The main objective of my project is to determine how the mechanisms for the evaluation of the nutritional value of food of D. suzukii larvae have adapted to the conquest of the fresh fruit as a preferred oviposition site.

I will collect data at three levels, to compare between species.

The environmental – Study the nutritional composition of their natural food sources.
The interface – Describe the the smell and taste receptors and their function.
The internal – Analyze the physiology and metabolism of larvae on different food sources.

The information and data produced by this project is important for society on several levels:

This is a project of basic science, about important aspects of ecology and evolution. Its results will add to the vast knowledge of humanity on how the natural world works.
Additionally, I will be studying the feeding preferences and basic needs of a species that causes damage to fruit production. This information may aid on the effort to reduce the economic loses we suffer from our interactions with this species.
On a third note, humanity faces many problems related to poor nutrition; obesity, cardiovascular disease and metabolic disorders are leading causes of death. These disorders are in most cases the results of disconnecting our nutritional needs from the composition of our diet, by eating mainly for pleasure. My research adds to the discussion of these subjects, because it analyzes taste preferences and nutritional needs to study the nature of the relationship between the composition of an optimal diet and a species’ role in the ecosystem and its evolutionary history.

Diego Galagovsky

A Biologist. A fly person. Passionate for science and drawing.