In reproduction, fertilization occurs after a successful copulation. Remember, all insects exhibit internal fertilization. This means that the egg and sperm nuclei fuse to form a zygote inside the female's reproductive tract. In insects, the reproductive system is located in the abdomen. Sexual organs often have a species-specific morphology and can be useful in species identification. Let's explore some important structures in the insect's reproductive system. Starting with female insects. The reproductive system of female insects is designed for sperm receipt, storage, and manipulation as well as egg production. Female insects have paired ovaries and each ovary contains one or more ovarioles where the eggs are produced. In the ovaries, the egg is loaded with yolk and other nutrients before being covered with a protective egg shell or chorion. The process of egg production is known as Oogenesis. Once Oogenesis is completed the egg is released from an ovariole and travels to the genital chamber through the oviducts. Here, it may be fertilized by sperm that was transferred to the female by the male during mating. A female insect can store sperm in a specialized sack called a spermatheca. The sperm can be kept viable for long periods within the spermatheca as an associated gland provides the sperm with essential nutrients. Queens of some ant species benefit from sperm storage. Prior to colony establishment, a queen ant will mate with multiple male drones and store the sperm she receives in her spermatheca. These sperm remain viable and allow her to produce millions of offspring throughout her long life that can exceed 20 years. After an egg has been fertilized in the female's genitals chamber, accessory glands can produce additional materials, such as glues which helped secure eggs to each other and onto surfaces. These secretions are applied to the egg during oviposition. In most insect species, females select sites with optimal environmental conditions to provide their offspring with access to essential resources. The egg then travels through the females ovipositor to be laid. The egg is most often laid when the embryo is at an early stage of development. The embryo is protected from the environment by the multi-layered chorion and includes a waxy layer that prevents water loss. A yoke provides nutrients to the developing embryo. Now that we have looked at the female reproductive system, let's turn our attention to the male counterpart. Male reproductive structures are specialized primarily for sperm production, storage, and delivery. Sperm production in insects occurs in the paired testes. In some insects, the testes are fused and appear as a single structure. Sperm are formed within the testes, and once fully developed, they travel from the testes to the seminal vesicles through tubes known as the vas deferens. Sperm can be stored in the seminal vesicles until mating. During mating, the sperm is delivered into the female's reproductive tract along with ejaculatory fluid produced by male accessory glands. The ejaculatory fluids help protect and nourish the sperm. Male accessory glands can have other functions. For example, they are important in the production of substances offered to females as nuptial gifts. Male accessory glands may even produce chemicals that influence female receptivity. In fruit flies, seminal fluid from the male can actually lower a female's desire for other mates. In other insects, accessory gland compounds make the female less attractive to other males by interfering with her pheromone production. Males can also prevent females from repeatedly mating by producing sperm lugs using ejaculatory fluid to block other males access to the female's reproductive tract. In extreme cases, it's the male's own ADA gets that breaks off and lodges within the female. Now that's dedication. Now, we're familiar with male and female reproductive structures and their basic functions in insects. Let's dive into the next video and explore the weird and wonderful modes of reproduction employed by insects.
