Egg Chorion Morphology and Egg‐Laying Behaviour of Backswimmer Notonecta viridis Delcourt, 1909 (Heteroptera: Nepomorpha: Notonectidae)

In this study, the egg‐laying behaviour and chorionic morphology of the eggs of the backswimmer Notonecta viridis Delcourt, 1909 (Heteroptera: Notonectidae) were described in detail using stereo, light and electron microscopy. Female N. viridis lays its eggs individually, horizontally attached to the surface. Eggs are elliptical, approximately 1.65–1.8 mm long and 0.56–0.61 mm wide. Newly laid eggs are slightly transparent and pale yellow in colour. The lateral edge of the egg tip contains a horn‐like structure, the micropyle. The chorion is often thick and ruffled, decorated with disorganized polygonal patterns. Aeropyle holes are located between the polygonal structures. Polygonal patterns appear simplified at the adhesion surface and basal region. In cross‐sections, the egg chorion reaches a thickness of up to 19.7 μm at the tuberculated boundaries of the hexagons, while decreasing to 7.12 μm in thinner regions. Ultrastructural examination of the chorion in cross‐section reveals that the innermost layer consists of the endochorion, and the outermost layer consists of the globular exochorion. This study highlights the spawning behaviour and egg morphology of N. viridis , a vital component of aquatic ecosystems. Clearly defining the egg stage, a critical phase in insect development, is crucial for ensuring the species' survival and its role in the ecosystem.