Egg size-dependent embryonic development in the desert locust, Schistocerca gregaria

Area of Science:

• Developmental biology
• Insect physiology
• Phenotypic plasticity

Background:

• Phenotypic plasticity in body size is influenced by developmental pathway modifications.
• Desert locust (Schistocerca gregaria) hatchlings exhibit egg size-dependent body size plasticity.
• The specific embryogenesis mechanisms regulating final embryonic body size remain under investigation.

Purpose of the Study:

• To elucidate the developmental pathway responsible for body size variation in S. gregaria hatchlings.
• To investigate how embryogenesis during egg development influences final embryonic body size.
• To compare early, middle, and late egg developmental stages in small and large S. gregaria eggs.

Main Methods:

• Comparative analysis of small and large eggs from S. gregaria.
• Monitoring egg and embryonic development across early, middle, and late stages.
• Measuring egg and embryo morphology and weight changes over 12 days post-oviposition.

Main Results:

• Crowd-reared females produced larger eggs than isolated-reared females.
• Egg developmental rate and initial embryo size were similar between small and large eggs.
• Large-egg embryos showed significantly greater size increase during katatrepsis due to enhanced yolk absorption.

Conclusions:

• Egg size influences final embryo size in S. gregaria, primarily through yolk availability and eggshell space during development.
• The amount of yolk and eggshell size during katatrepsis are critical factors determining hatchling body size.
• Egg size does not affect the developmental rate or initial embryo size, but impacts post-blastokinesis growth.