The yellow mealworm beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae), has long been used as a key study organism in many fundamental researches, including biochemistry, physiology, and behavior. Lifespan and reproduction are two of the most important components of fitness in all insects, but it remains largely unexplored how these two traits are influenced by macronutrient intake in this beetle. In this study, we used the nutritional geometry framework to analyze the complex and interactive effects of dietary protein and carbohydrate intake on lifespan and reproductive performance in T. molitor beetle. Lifespan and the number of eggs laid throughout the lifetime were quantified from more than 2,000 individual beetles provided with one of 35 chemically defined diets representing a full combination of seven protein-to-carbohydrate ratios (P:C= 0:1, 1:5, 1:2, 1:1, 2:1, 5:1, or 1:0) and five protein plus carbohydrate concentrations (P+C=25.2, 33.6, 42, 50.4, or 58.8 %, dry mass). All measures of lifespan and egg production were expressed highly at high caloric intake, but they differed in the optimal P:C ratio where traits peaked. While lifespan was the longest at a moderately carbohydrate-biased P:C ratio of 1:1.36, the rate of egg production was maximized at a protein-biased P:C ratio of 1.75:1, suggesting a possible nutrient-mediated trade-off between lifespan and daily reproductive efforts in T. molitor beetles. Lifetime egg production was maximized at a P:C ratio of 1.31:1, which was still protein-biased but lower than that maximized egg production rate. Reproductive lifespan was the longest at a P:C ratio of 1:1.06. When given a food choice, T. molitor beetles preferred a P:C ratio of 1:1, which is closest to the ratio that enables T. molitor beetles to stay reproductively active as long as possible.

Recent research has suggested that the dietary protein:carbohydrate (P:C) balance is a critical determinant of fitness in insects. In this study, we examined the effects of dietary P:C balance on life-time reproductive success in the mealworm beetle, Tenebrio molitor. Both males and females lived the longest when fed on P:C 1:1 diet. Throughout their adult lives, females fed on P:C 1:1 diet laid significantly more eggs than those on nutritionally imbalanced diets (P:C 1:5 or 5:1). When given a choice, beetles regulated their intake of protein and carbohydrate to a ratio close to 1:1. Taken together, our results indicate the balanced intake of protein and carbohydrate maximizes life-time reproductive success in this species.

Protein and carbohydrate are the two most important macronutrients that have profound impacts on fitness and demography in most insects. The purpose of this study is to investigate the effects of dietary protein:carbohydrate (P:C) balance and mating status on feeding behavior, longevity and fecundity in male and female mealworm beetles, Tenebrio molitor (Coleoptera: Tenebrionidae). In the first experiment, we measured the amount of protein and carbohydrate consumed by mated and unmated beetles of both sexes. Newly emerged beetles were allowed to mate for 24 h before they were simultaneously provided with two nutritional imbalanced but complementary synthetic diets (P:C =1:5 vs. 5:1) for 24 successive days. Mated females not only consumed significantly more nutrients but also exhibited a greater preference for protein than did mated males and unmated controls. In the second experiment, we determined longevity and fecundity from a total of 120 male and female beetles that were confined to feed on one of three no-choice foods differing in P:C balance (P:C=1:5,1:1 or5:1) throughout their entire lives. Fecundity was recorded as the total number of eggs laid by individual females until death. Both male and female beetles lived significantly longer and laid more eggs over the lifetime on a balanced diet (1:1) than on the two imbalance diets (1:5 and 5:1), suggesting that the Darwinian fitness was maximized when the diet was equally balanced in protein and carbohydrate. Mated male and female beetles had a shorter longevity compared to their unmated counterparts, indicating that there was a significant survival cost to mating in this insect.

Protein and carbohydrate are the two most important macronutrients that have profound consequences for the fitness of insects. Many insects are capable of balancing the intake of multiple nutrients to minimize the fitness costs associated with ingesting diets that are imbalanced with respect to protein and carbohydrate. It has been hypothesized that insects will redress the imbalance of their nutrient state through increasing the appetite for specific nutrients that are ingested in deficit. We tested this possibility using a mealworm beetle, Tenebrio molitor (Coleoptera: Tenebrionidae). Newly emerged beetles were confined to one of two nutritionally imbalanced foods that contained only protein or carbohydrate (P:C ratio = 0:42 and 42:0, expressed as % dry mass) for 16 days, after which they were given an opportunity to choose between two nutritionally imbalanced diets (0:42 versus 42:0). Over the first few days of the food choice, beetles that had previously experienced protein-limitation preferred protein to carbohydrate while the reverse was true for those that had experienced carbohydrate-shortage. Such contrasting patterns of diet preference observed between the two groups of beetles diminished subsequently as the insects recovered from nutrient imbalance. Our results provide strong support for the long-standing idea that attaining the right balance of nutrients is the main motive for foraging in insects.

갈색거저리의 온도에 따른 유충 발육시험을 15, 17, 20, 22, 25, 28 및 30℃의 7개 항온조건, 광주기 14L:10D, 상대습도 60~70% 조건에서 수행하였다. 유충은 13령까지 경과하였고 항온 조건에서 사망률은 17, 20℃에서 극소수 개체만이 발견되었고, 22℃ 이상의 항온조건에서는 발견되지 않았다. 유충의 발육기간은 17℃에서 244.3일로 가장 길었고, 30℃에서 110.8일로 가장 짧았다. 15℃는 부화되지 않아 유충 발육 조사가 불가능하였다. 온도와 발육율과의 관계를 알아보기 위하여 선형모형과 비선형모형(Logan 6)을 이용하였으며, 선형모형을 이용하여 추정한 전체유충의 발육영점온도는 6.0℃, 발육 유효적산온도는 2564.1DD 였으며 선형, 비선형 모두 결정계수값(r2) 이 0.95로 높은 값을 보였다. 전체유충의 발육완료분포는 2-parameter Weibull 함수를 사용하였으며 전체 유충의 결정계수 값은 0.8502~0.9390의 양호한 모형 적합성을 보였다.

Cry3 toxins from Bacillus thuringiensis are used as biopesticides and the transgenic crops to control of leaf-feeding beetles. Cadherin in insect midgut epithelium is identified as receptor for Cry toxins in several insects and some domains of it synergizes Cry toxicity. Cadherin (DvCad1-CR8-10) fragment of Diabrotica virgifera virgifera enhanced Cry3Bb toxicity to Colorado potato beetle (CPB), Leptinotarsa decemlineata. Single cadherin repeat (CR) fragment of DvCad1-CR8-10, have a strong binding affinity to the active Cry3Bb toxin. The dissociation constant Kd value of CR8, CR9, and CR10 were 4.9 nM, 28.2 nM, and 4.6 nM, respectively. Interestingly, CR8 and CR10 enhanced Cry3Bb toxicity against CPB and Lesser mealworm (LMW), Alphitobius diaperinus, neonates in up to 2-folds. The DvCad1-CR10 peptide is further analyzed by in-frame deletion to determine the active site for Cry3Bb toxin. The active site is narrowed down to a 26 amino acid locating in the N-terminal region of DvCad1-CR10 that either synergized Cry3Bb toxicity on the CPB and LMW neonates in 3-folds or bound to the toxin with high affinity. The extent of Cry3Bb toxin enhancement by the activie site in DvCad1-CR10 may have practical application for control of CPB and LMW.

The developmental time of larvae of mealworm beetle, Tenebrio molitor was studied at six temperatures ranging from 17 to 30℃ with 60~70% RH, and a photoperiod of 14L:10D. Mortality of 1st~13th larva was very low at 17 and 20℃ but did not die over 22℃. Developmental time of larva decreased with increasing temperature. The total developmental time was longest at 17℃ (244.3 days) and shortest at 30℃ (110.8 days), suggesting that the higher temperature, the faster development period. The lower developmental threshold temperature and effective accumulative temperatures for the total larval stages were 6.0℃ and 2564.1 day-degrees. The relationship between developmental rate and temperature fitted a linear model and nonlinear model by Logan-6 (r2=0.95). The distribution of completion of each development stage was well described by the 3-parameter Weibull function (r2=0.89).