Shumo Marwa, Khamis Fathiya M, Tanga Chrysantus M, Fiaboe Komi K M, Subramanian Sevgan, Ekesi Sunday, van Huis Arnold, Borgemeister Christian
Center for Development Research (ZEF), Department of Ecology and Natural Resources Management, 53113 Bonn, Germany.
International Centre of Insect Physiology and Ecology (icipe), Plant Health Unit, Nairobi 00100, Kenya.
Animals (Basel). 2019 Mar 2;9(3):79. doi: 10.3390/ani9030079.
In sub-Saharan Africa, urban populations are projected to increase by 115% in the coming 15 years. In addition, economic growth and dietary shifts towards animal source foods have put high pressure and demand on agricultural production. The high ecological footprint of meat and dairy production, as well as high feed costs, prevent the livestock sector from meeting the increasing demand in a sustainable manner. Insects such as the black soldier fly (BSF) have been identified as potential alternatives to the conventionally used protein sources in livestock feed due to their rich nutrient content and the fact that they can be reared on organic side streams. Substrates derived from organic byproducts are suitable for industrial large-scale production of insect meal. Although efficient in waste management and in feed production, BSF larvae are very sensitive to the external environment such as temperature and rearing medium. Therefore, we studied the effect of temperature and substrate type, i.e., brewers' spent grain (SG) and cow dung (CD), on the development and survival of BSF larvae. Both organic substrates were readily available in Nairobi, Kenya, the location of the experiments. In our experiment, 100 3⁻5-day-old BSF larvae were placed into containers that contained either SG or CD and further treated at temperatures of 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C. The duration of larval development was recorded, and the prepupae were removed, weighed, and placed individually in separate, labeled, 35-mL plastic cups filled with moist sawdust. After emergence, 10 2-day-old adults (5 males and 5 females) from every replica per substrate were transferred into a cage (40 × 40 × 40 cm) and allowed to mate for 24 h at their respective temperatures. The laid egg batches were collected and counted, and the adult flies' longevity was recorded. The data were subjected to a two-way analysis of variance (ANOVA) using the general linear model procedure. BSF larvae reared on SG developed faster than those reared on CD; the former also favored higher temperatures for their larval development and emergence into adults. The optimum range was 25⁻30 °C. With increasing temperatures, the longevity of adult BSF decreased, while the fecundity of females increased. Thus, it is possible to take advantage of the readily available SG waste streams in the urban environments of Kenya to produce BSF larvae-derived livestock feed within a short duration of time and at relatively high temperatures.
在撒哈拉以南非洲地区，预计未来15年城市人口将增长115%。此外，经济增长以及饮食向动物源食品的转变给农业生产带来了巨大压力和需求。肉类和奶制品生产的高生态足迹以及高昂的饲料成本，使得畜牧业难以以可持续的方式满足不断增长的需求。诸如黑水虻（BSF）等昆虫因其丰富的营养成分以及能够以有机副产品为食进行饲养，已被确定为家畜饲料中传统蛋白质来源的潜在替代品。源自有机副产品的底物适合用于昆虫蛋白的工业化大规模生产。尽管黑水虻幼虫在废物管理和饲料生产方面效率很高，但它们对温度和饲养基质等外部环境非常敏感。因此，我们研究了温度和底物类型（即啤酒糟（SG）和牛粪（CD））对黑水虻幼虫发育和存活的影响。这两种有机底物在实验地点肯尼亚内罗毕都很容易获得。在我们的实验中，将100只3 - 5日龄的黑水虻幼虫放入装有SG或CD的容器中，并在15℃、20℃、25℃、30℃和35℃的温度下进一步处理。记录幼虫发育的持续时间，取出预蛹，称重，并分别放入单独的、标有标签的、装有潮湿锯末的35毫升塑料杯中。羽化后，从每个底物的每个重复样本中选取10只2日龄的成虫（5只雄性和5只雌性）转移到一个笼子（40×40×40厘米）中，并在各自温度下让它们交配24小时。收集并计数产下的卵块，记录成虫的寿命。使用一般线性模型程序对数据进行双向方差分析（ANOVA）。以SG饲养的黑水虻幼虫比以CD饲养的发育更快；前者在幼虫发育和羽化为成虫时也更喜欢较高的温度。最佳温度范围是25 - 30℃。随着温度升高，黑水虻成虫的寿命缩短，而雌虫的繁殖力增加。因此，有可能利用肯尼亚城市环境中容易获得的SG废物流，在短时间内并在相对较高的温度下生产出源自黑水虻幼虫的家畜饲料。
