Microsurgical Obstruction of Testes Fusion in Spodoptera litura

This protocol suggests that a physical method can be adopted to assist in figuring out biological problems. This technique provides a method to place material in insects with minimum incision and study the influence of microsurgery on individuals’development. This method can apply to other Lepidoptera larvae and other parts of the insects, including the head and thorax.

It is very important to practice making incisions in certain material and suturing skillfully. Begin by placing Spodoptera litura male larvae at day 4 of the 6th instar, or L6D4, on ice for 10 to 30 minutes to keep them anesthetized during the operation. Place the anesthetized larva on the wax tray with the dorsal side up.

Fix the head and the tail of the larva with pins and threads and disinfect the surgical area by applying 3%iodine tincture with a cotton swab to the epidermis, followed by 70%alcohol. Make a 2 millimeter-long incision on the dorsal epidermis at the 9th body segment and use a sterile cotton swab to remove leaking hemolymph and fat bodies to obtain a clear view of the surgical area. Using surgical tweezers, insert a piece of aluminum foil between the testes, and then close the epidermis with a running suture.

Tie a surgical square knot with the help of a needle holder and surgical tweezers. Cut the excess suture from the loop tails with scissors, leaving a 2-millimeter thread behind. After suturing, gently lay the larva in the rearing box and maintain them in a clean environmental simulation chamber with continuous observation.

The growth and development of the Spodoptera litura male larvae post-microsurgery was monitored. The larval mortality rate was slightly higher in the surgical group, whereas the percentages of pupation, adult emergence, and successful mating were slightly lower in the surgical group than in the control group. In the experimental group, the number of total sperm bundles in eupyrene and apyrene sperm bundles were significantly lower than the control and sham control group.

On the other hand, the percentages of eupyrene sperm bundles had no significant differences among all three groups. After removing a unilateral testis of the larvae, the numbers of total sperm bundles and eupyrene and apyrene sperm bundles in microsurgery groups were significantly lower than the control group. The percentage of eupyrene sperm bundles on the sixth day of the pupal stage was comparable in all three groups.

It is very important to notice the location of the wound and avoid damaging other organs during the incision. This technique can be used to study the biological significance of testicular fusion by applying drugs to the organs. The drugs’effect on the target organ can be explored.