The two sibling species of fruit fly, Drosophila melanogaster and D. simulans (Diptera: Drosophilidae), have long been used as the key model organisms in ecological and evolutionary research. While numerous studies have investigated the thermal responses of these two species, no study has yet systematically compared their response to dietary macronutrient balance. To fill this knowledge gap, we compared how various life-history traits expressed during larval development would response to an array of dietary ratio of protein to carbohydrate (P:C ratio) in these two sibling species. Largely consistent with previous studies, D. melanogaster took longer to complete their larval development and were much larger at adult emergence than D. simulans. For both species, an increase in dietary P:C ratio resulted in improved larval survivorship and faster development. However, the two species showed qualitatively different response to dietary P:C ratio when body mass at adult eclosion was concerned. The body mass of D. melanogaster peaked at an optimal P:C ratio of 1:4, but decreased as the P:C ratio either increased or decreased from this optimum. In marked contrast, the body mass of D. simulans was insensitive to dietary P:C ratio.

Temperatures experienced during larval development can exert profound effects on life-history traits expressed later during the adult stage in insects. In this study, we explored how larval rearing temperature (18, 23, and 28℃) would affect adult lifespan and reproductive performance in Drosophila melanogaster Meigen (Diptera: Drosophilidae). Larval developmental period was shortened with increasing rearing temperature. Larvae reared at colder temperatures reached the adult stage at a larger size than those reared at higher temperatures, thus conforming to the temperature-size rule. More importantly, we found strong evidence for significant effects of larval rearing temperature on both adult lifespan and early-life egg production rate. Lifespan increased progressively as the larval rearing temperature decreased from 28 to 18℃. In contrast, egg production rate was lower for flies raised at 18℃ compared to those at 23 and 28℃. These results highlight the importance of thermal environments experienced during the development in shaping life-history plasticity in insects.

Diet and temperature are the two most critical environmental factors affecting life-history traits in insects, but the combined effects of these factors have been rarely investigated. In this study, various life-history traits were recorded from adult and larval Drosophila melanogaster fed on one of eight synthetic diets differing in protein:carbohydrate ratio (P:C=1:16, 1:8, 1:4, 1:2, 1:1, 2:1, 4:1, or 8:1) under one of six ambient temperatures (13, 18, 23, 28, 31, or 33oC). The patterns of adult and larval life-history traits expressed across 48 diet-by-temperature combinations were visualized using thin-plate spline technique and the presence of any significant linear, quadratic, and correlational effects of diet and temperature on trait expressions was analyzed using a second-order polynomial multiple regression. Life-history traits exhibited qualitatively different responses to variations in both diet and temperature, with the maximal expression of each trait being achieved at a completely divergent region of the diet-temperature fitness landscape. In adult females, for example, lifespan was maximized at P:C 1:16 under 13oC, but fecundity was maximized at P:C 4:1 under 28oC. These results provide empirical support for the emerging notion that environmental factors, such as diet and temperature, can mediate life-history trade-offs in insects.

Protein and carbohydrate are two major macronutrients that exert profound influences over fitness in many insects, including Drosophila melanogaster. Until recently, most studies examining the impacts of these macronutrients on various life-history traits in this species have used semi-synthetic diets that are not nutritionally well-defined. Here we used chemically defined diets to examine the patterns of larval and adult traits expressed across 34 diets systematically varying in the ratio and concentration of protein and carbohydrate. The shapes of the nutritional landscapes plotted for all larval and adult traits differed significantly from one another. Diverging nutritional optima identified for these landscapes suggest that D. melanogaster cannot maximize the expression of all life-history traits simultaneously, thus leading them to face a nutrient-dependent life-history trade-off.

Tetranychus piercei McGregor, T. truncatus Ehara, and T. bambusae Wang and Ma are considered as major pests of many agricultural crops in Bangladesh. T. piercei and T. truncatus has a diverse host plants although T. bambusae infest only bamboo leaves. We compared the development, survivorship, and life table parameters of T. piercei and T. truncatus on bean leaves and T. bambusae on bamboo leaves at 25ºC, 60-70% RH, and a photoperiod of 16: 8 h (light: dark). The development time from egg to adult female of T. piercei and T. truncatus was 10.2 and 8.8 days when feeding on bean leaves, respectively, whereas it takes 9.5 days for female T. bambusae when feeding on Bambusa sp. leaves. Mated females of T. piercei, T. truncatus, and T. bambusae laid on average 186.9, 132.5, and 46.3 eggs for the oviposition period of 22.3, 13.5, and 20.2 days, respectively. The intrinsic rate of increase (rm) was 0.268 for T. piercei, 0.295 for T. truncatus, and 0.178 for T. bambusae. The finite rate of increase (λ) was 1.31, 1.34, and 1.20 individuals/female/day for T. piercei, T. truncatus, and T. bambusae, respectively. The doubling time (Dt) was lowest in T. truncatus (2.4 days) compare to T. piercei (2.6 days) and T. bambusae (3.9 days). The two polyphagous Tetranychus mites collected in Bangladesh are found to have similar life table parameters fall within the parametric range of other Tetranychus mites found in various regions irrespective of food sources. This is the first report of life table parameters of monophagous T. bambusae.

환경상태는 생물이 적합도 (번식성공 또는 생존율)를 극대화하기 위해서 초기생활사의 변화를 초래할 수 있 다. 본 연구에서는 온도변화와 온도에 따른 수상레저활동 인구변화가 어류의 초기 생활사 특성, 즉 체세포 성장(성 장속도), 번식세포 (생식소) 발달 그리고 누적스트레스의 회복과정과 어떠한 관계가 있는지를 동적상태의존모델을 이용하여 분석하였다. 우선 어류의 초기 생활사 특성이 취식행동에 영향을 받는다고 가정하였고, 이러한 관계를 고려하여 어류의 일반 생활사 모델을 개발하였다. 모델은 성장속도와 번식세포(생식소)의 발달이 온도가 상승함에 (단, 성장속도를 감소시키는 임계온도보다는 낮은) 따라 빨라졌으며, 또한 체내에 누적되는 스트레스도 함께 증가 하였다. 흥미롭게도 온도가 높을 때에는 수상레저활동 인 구의 증가는 성장속도와 생식소의 발달을 느리게 했지 만, 스트레스의 누적은 가속화시켰다. 그러나 온도가 낮 을 때에는 초기 생활사에 대한 수상레저활동 인구의 영 향이 상대적으로 낮았다. 또한 최적취식행동은 높은 온도 에서는 수상레저활동 인구의 변화에 관계없이 항상 높았 지만, 낮은 온도에서는 수상레저활동 인구가 증가할 수록 급격히 감소하였다. 초기성장기간 동안의 생존율은 온도 가 낮아지고 수상레저활동 인구가 적을 때에는 취식행동 이나 인간 활동에 따른 어류의 사망률 증감이 생존률 변 이에 영향을 주었다. 반대로 온도가 높아지고 수상레저활 동 인구가 많을 때의 생존율은 취식행동이나 사망률에 관계없이 항상 낮았다. 끝으로 본 연구를 통해 기후변화 와 수상레저활동 인구변화와 관련된 어류의 초기 생활사 를 수생태계 보전전략이나 건강성 평가분석에 포함시키 는 것은 분석의 정확성과 정밀성을 향상시킬 수 있을 것 이라 사료된다.

A new collembolan species (Paranura rosea) which was native to Korea was selected for evaluating the effect of temperature on their biology. Development, and reproduction of P. rosea were investigated at 15, 20, 25 and 30℃ Hatchability of egg was not affected by experimental temperature, and the lower threshold temperature for development of P. rosea was estimated to be 7.53℃. The temperature reduced the juvenile and adult (maturity period). The intrinsic rate of natural increase and finite rate of increase per week at 20℃ which are maximum values showed significant difference with other experimental temperatures. Survival rate, cumulative reproduction and head capsule width was fitted by several models. Especially, the model which fitted for estimating head capsule width was used to determine their life stage. Estimated head capsule width of P. rosea at the initial oviposition varied with temperature from 0.36 ± 0.007 to 0.45 ± 0.007 with maximum at 20℃ and minimum at 30℃, and significant difference was observed at all the experimental temperature (P<0.05). However, estimated head capsule width at the last oviposition showed different statistically result at only 30℃. Molting frequency per week of one P. rosea was increased as the temperature increased. Based on this study, temperature greatly influenced on their life stage and reproduction. Therefore, relationship between temperature and P. rosea is very important for understanding their biology.

A phytoseiid mite, Neoseiulus californicus was newly found from Jeju citrus orchards in Korea and it is a polyphagous predator of mite and small insect pests as well as plant pollens. Recently in Korean apple orchards, Tetranychus urticae and Panonychus ulmi are imposing similar pest pressure. Even with ample information of this predator interacting with T. urticae, little is known on the interaction with P. ulmi. We investigated temperature effects on life history parameters of N. californicus when feeding on P. ulmi as prey in the laboratory condition to check the possibility to use this predatory mite in apple mite biological control. So, the development, survivorship and life-table parameters of the predator were studied by given mixed stages of P. ulmi as prey under the range of temperatures (15-34°C), RH 75±10%, and photoperiod 16L:8D to determine the effects of temperature. Temperature had a significant effect on mean development time from hatching to adult emergence and other life-history parameters. The results specified that the developmental time is decreased with increasing temperature between 15 and 30oC. Female development times were shorter at 25, 30 and 34°C (3.83±0.07, 3.37±0.24 and 3.53±0.11d, respectively) and were longest at 15°C (15.61±0.22d). Male developmental times were shorter than females ones at each temperature. The highest adult female life span (70.42±3.06d) and oviposition period (35.83±1.43d) observed at 15oC whereas the shortest at 34oC (13.06±1.03 and 7.3±0.94d, respectively). At 25oC, females laid maximum number of eggs (63.94±2) while minimum (16.59±0.98) was at 34oC. In sex ratio, utmost number of females (0.77±0.01) was counted at 25oC and lowest (0.67±0.01) at 34oC. Survivorship during immature development varied from 78.78 to 93.75% with the lowest value recorded at 20 and 34oC. From life table analysis, the shortest generation time (T=10.7d) resulted at 34oC. The highest net reproductive rate (R0=44.31; expected progeny per female) was found at 25oC. The intrinsic rate of natural increase (rm=0.29) and the finite rate of increase (λ=1.33) per day was estimated highest at 30oC. From this study, we found that N. californicus could successfully develop and oviposit vital eggs. Based on these results, we cautiously expect that N. californicus could be used as a biocontrol agent of spider mites in apple orchards when P. ulmi or T. urticae occurs singly or mutually.