Morphology of the Female Reproductive System of the Soybean Thrips, Neohydatothrips variabilis (Beach, 1896) (Thysanoptera: Thripidae)

Abstract

Soybean thrips (Neohydatothrips variabilis) are an important phytophagous vector of the widely recognized Soybean vein necrosis orthotospovirus (SVNV). Understanding the egg-laying behavior of these thrips could aid in developing strategies for the management of the vector and virus. In this study, we described the egg-laying behavior of N. variabilis and reconstructed the three-dimensional morphology of the female terminalia by using serial block-face scanning electron microscopy (SBFSEM) and confocal laser scanning microscopy (CLSM). The female reproductive system consists of two panoistic ovaries consisting of eight ovarioles. The appendage gland is connected to the ovaries by two muscles, and to the body wall by a single muscle. The spermatheca is connected to the eighth tergum through four branched muscles, to the basivalvulae of the ovipositor by one muscle and to the vagina by a single muscle. The external genitalia are operated by seven muscles. The movement of the eggs inside the ovipositor is achieved by the back and forth “rocking” movement of the first valvulae and valvifer. Eggs are deposited into the parenchymatous tissue alongside leaf veins. To the best of our knowledge, this is the first study describing the internal and external genitalia of N. variabilis.