TTPP Nº2: Aparatos bucales picador suctor y raspador suctor (Módulo 2)

Introduction to Oral Apparatuses in Insects

Overview of the Module

• The session focuses on practical number two regarding oral apparatuses, specifically the piercing and scraping types.

• Objectives include analyzing these oral structures, recognizing their components and modifications, and relating them to damage symptoms caused by these mouthparts.

Structure of Masticatory Apparatus

• The masticatory apparatus is transformed into various pieces that differ in shape and size for cutting and grinding food.

• Key components include mandibles that open sideways, a hypopharynx acting like a tongue, which will be modified in piercing-sucking mouthparts.

Transformation into Piercing-Sucking Mouthparts

Modifications of Mouthparts

• Mandibles evolve into external stylets while maxillae transform into internal stylets; the lower jaw forms a protective tube for resting stylets.

• A detailed examination reveals rudimentary parts such as the labrum and how they fit together within the oral cavity structure.

Feeding Mechanism

• Insects use their modified mouthparts to pierce plant surfaces, injecting saliva through one channel while drawing nutrients through another larger channel. Saliva contains enzymes that partially degrade tissues causing harmful effects.

Damage Caused by Piercing-Sucking Mouthparts

Types of Damage

• Direct damage includes blood suction and toxic reactions from saliva (toxemia), while indirect damage involves pathogen transmission leading to further complications. Symptoms may include leaf curling or grain malformation.

Examples of Insect Orders

• Various insects with this type of mouthpart include true bugs (Hemiptera), cicadas, whiteflies, aphids, scale insects, and even some mosquitoes during their adult stage; they feed on plant juices or blood from other organisms.

Characteristics of Scraping Mouthparts

Unique Features

• Scraping mouthparts are characterized by asymmetry typical in certain insect orders like Thysanoptera (thrips). Only one mandible is functional while the other is reduced to a stylus form; maxillae also become stylized for feeding purposes.

Feeding Process

• Thrips utilize their cone-shaped mouthpart structure to penetrate host tissues for feeding; this results in visible damage at cellular levels leading to air-filled cells reflecting light—creating a silvered appearance on affected plants.

Functional Components and Indirect Effects

Summary of Functional Parts

• The left mandible along with maxillae serve as primary functional components directly involved in feeding processes among thrips; they cause both direct tissue damage and indirect pathogen transmission through salivary toxins leading to various symptoms post-feeding including deformities in fruits or leaves based on attacked buds or flowers.

Conclusion

This module provides an extensive understanding of how different insect oral apparatuses functionally adapt for feeding while also highlighting significant agricultural impacts due to their interactions with plants.