In blister beetles (Meloidae), what is the name of the first larval instar?

In blister beetles (Meloidae), what is the name of the first larval instar?

• A. Planidium
• B. Nauplius
• C. Triungulin
• D. Polyungulin

Answer: (C)

In blister beetles, the first larval stage is a specialized mobile form called a triungulin. This name reflects its striking life history: after the eggs hatch, this instar is active and legged, designed to actively seek out a host rather than staying sedentary like later larval stages. The triungulin is typically equipped with three pairs of legs and is adapted to locate and invade the appropriate host environment, such as bee nests where the beetle larvae will parasitize or consume bee brood. This early instar embodies the beetle’s hypermetamorphosis, where the initial larva is drastically different from the later grub-like instars. Once the triungulin finds and enters a suitable host, it molts into subsequent, less mobile larval stages that are more grub-like and focused on feeding inside the host context. Other terms like planidium or nauplius refer to different insect or crustacean larval forms not characteristic of blister beetle development, and polyungulin is not the standard first instar term for Meloidae.

In blister beetles, the first larval stage is a specialized mobile form called a triungulin. This name reflects its striking life history: after the eggs hatch, this instar is active and legged, designed to actively seek out a host rather than staying sedentary like later larval stages. The triungulin is typically equipped with three pairs of legs and is adapted to locate and invade the appropriate host environment, such as bee nests where the beetle larvae will parasitize or consume bee brood.

This early instar embodies the beetle’s hypermetamorphosis, where the initial larva is drastically different from the later grub-like instars. Once the triungulin finds and enters a suitable host, it molts into subsequent, less mobile larval stages that are more grub-like and focused on feeding inside the host context. Other terms like planidium or nauplius refer to different insect or crustacean larval forms not characteristic of blister beetle development, and polyungulin is not the standard first instar term for Meloidae.