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.
Temperature and nutrition are the two most important environmental factors influencing growth and survival in immature insects. There is ample evidence of interactions between these two factors but still little is known how changes in thermal environment affect feeding and nutrient utilization insect ectotherms. The aim of this study is to investigate the potential effects of ambient temperature on food selection and post-ingestive nutritional physiology in a generalist-feeding caterpillar of Spodorptera litura. Two separate experiments were performed. The first was a food choice experiment in which caterpillars were maintained through their final larval stadium under one of three constant temperatures(20,25,30°) and given a choice between two nutritionally unbalanced diets that differed in protein(p) and carbohydrate(c) content (p42:c0 vs p7:c35 and p35:c7 vs p7:c35). In the second experiment, caterpillars were kept at the same thermal conditions as the first experiment but received a single diet from three no-choice feeding treatments(p35:c7,p21:c21and p7:c35). When raised at the highest temperature (30C), caterpillars from the choice experiment selected significantly more carbohydrate than those on lower temperatures whereas protein intake did not differ significantly between caterpillars across three test temperatures. Results from the no-choice experiment showed that lipid storage efficiency was reduced when caterpillars were maintained at the highest temperature(30C). In both experiments, growth rate increased progressively with rising temperature. However, there was a significant temperature-by-diet interaction, with growth rates increasing more rapidly on p21:c21 diet than on the other diets(p35:c7 and p7:c35). Our results demonstrate that caterpillars adjust their nutrient preference to meet the increased energetic demand at high ambient temperature.
실과용으로 적합한 양액종류를 선발하고자 수경재배용으로 선발한 '금장외대파'와 '토쿄구로파'을 공시하여 담액식으로 시험을 수행하였다. 양액종류로 기존 파용 지바농시액, 엽채소용 M식액, 파용 타케가와액, 및 싹파용 야마자키액을 이용하여 시험한 결과, 구당 생체 중 및 건물중에 있어서 두 품종 모두 야마자키액, M식액, 지바농시액, 타케가와액 순으로 양호하였다. 생체중과 건물중 증가, 그리고 양분 흡수율 및 기타 요인을 모두 고려하였을 때 실파 수경재배용으로 가장 적정한 배양액으로 싹파용 야마자키액을 선발하였다.
본 연구는 답리작에서 사일리지용 보리 우량품종 선발을 위해 경기 수원(축산연)에서 1999 ∼ 2001년까지 3년간 생육단계별로 사료가치 및 TDN수량 등을 조사하였다. 총체보리의 유숙기 때의 ADF 함량은 27.3 ∼ 29.1% 이었고 황숙기의 경우 27.4 ∼ 30.4%이었다. 또한 유숙기와 황숙기 때의 NDF 함량은 50.6 ∼ 55.9% 그리고 53.1 ∼ 60.6. 유숙기와 황숙기의 TBN 함량은 65.4 ∼ 67.4% 그리고 64. 3 ∼ 6