Developmental characteristics of Tenebrio molitor larvae (Coleoptera: Tenebrionidae) in different instars

Abstract

Tenebrio molitor is a major pest of stored grain, although its larvae have potential for use as food. However, little is known about the characteristics of individual larval instars of this species, and the number of instars remains disputed. Therefore, we assessed T. molitor for the average number of instars and its characteristics at different larval stages. The focus of this study was to establish a foundation for further studies on the characteristics of each larval instar. All of the T. molitor larvae showed incubation periods of 7 to 8 d and a period of 3 to 4 d for the 1 st instar. Beyond the 1 st instar, there were relatively large variations in the number of days in each instar period. Before emergence, most of the larvae had typically gone through 15 to 17 instars. The highest rate of pupae formation, 28.32%, was observed in the 17 th instars. The body length gradually increased with each successive instar, reaching its maximum at the 17 th instar. Beyond the 17 th instar, however, the body length decreased. The larvae were white in the first instar, and gradually turned brown after the 2 nd instar. IntroductionTenebrio molitor is a holometabolous insect that is considered to be a harmful pest of stored grain in South America (Schroeckenstein et al., 1990). However, its larvae, commonly referred to as mealworms, are used as pet food in many countries (Cotton, 1927). Because they are high in protein and fat and consume large amount of fiber, they represent a good food source for humans (Finke, 2002). Furthermore, they are high in oleic acid, which has the ability to decrease low-density lipoprotein (LDL) and increase high-density lipoprotein (HDL) levels in the blood (Yoo et al., 2013). In addition, they are inexpensive and easy to raise, with minimal harmful effects on the environment (Wang et al., 2012). For these reasons, many studies have been conducted on T. molitor to determine its potential uses.The physiological features of T. molitor have been studied in some detail. Several studies on these aspects have found that the age of the parents influences the development of larvae; young parents are associated with the highest egg hatching rates (Ludwig and Fiore, 1960).

SPME‐GC/MS Analysis of Volatile Compounds Contained in the Insect Larvae of Tenebrio molitor and Leptinotarsa decemlineata before and after Using Insecticides

“…Tenebrio molitor (Tenebrionidae) and Leptinotarsa decemlineata (Chrysomelidae) are harmful species that destroy mainly crops . T. molitor is a synanthropic species found in various environments related to human activities.…”

“…In addition to their negative impact, these insects also have a positive use . In many countries, they are prepared as food, being considered a large source of protein and fat, both for animals and for humans . T. molitor larvae contain large amounts of C18 : 1 oleic acid, which lowers LDL and raises HDL in the blood .…”

“…In many countries, they are prepared as food, being considered a large source of protein and fat, both for animals and for humans . T. molitor larvae contain large amounts of C18 : 1 oleic acid, which lowers LDL and raises HDL in the blood . L. decemlineata is a harmful species that feeds on plants from the Solanaceae family, mainly potatoes and sometimes tomatoes .…”

Two Roles for the Tenebrio molitor Relish in the Regulation of Antimicrobial Peptides and Autophagy-Related Genes in Response to Listeria monocytogenes

“…T. molitor was maintained under standard conditions (at 27 ± 1 • C and 60 ± 5% RH) in the dark because they are nocturnal [21,22]. The insects were fed on an artificial diet consisting of 170 g of wheat flour, 0.5 g of chloramphenicol, 20 g of roasted soy flour, 0.5 g of sorbic acid, 0.5 mL of propionic acid, 10 g of soy protein, and 100 g of wheat bran in 200 mL of distilled water.…”

Sustainable farming of the mealworm Tenebrio molitor for the production of food and feed

“…As discussed previously, rearing mealworms under suboptimal conditions increases the risk of infections [100,101]. The optimal growth temperature is 25 °C-27.5 °C, resulting in a [102,103]. Individual food consumption and larval weight depend on the larval density, i.e.…”