基于RFID技术的西方蜜蜂采集行为研究

蜜蜂能够灵活调整出巢觅食行为,从而有效保证蜂群的正常发育与繁衍.为了探索采集蜂的行为特性,本文利用由江西农业大学蜜蜂研究所与广州市远望谷信息技术股份有限公司合作研发的蜜蜂无线射频识别(RFID)系统,对西方蜜蜂进行为期38 d的全天候监控记录.结果表明: 两蜂群中分别有63.4%和64.5%的采集蜂存在轮休现象,轮休时间比例为22.5%~26.4%;轮休与非轮休蜜蜂的采集工作总量差异不显著,但轮休蜜蜂寿命显著高于非轮休蜜蜂;提前发育的采集蜂的寿命显著低于正常采集蜂.本研究丰富了蜜蜂社会行为学内容,为进一步探索蜜蜂采集行为的形成机制奠定了基础.     

Can models of density-dependent habitat selection be applied for trap-building predators?

Density-dependent habitat selection theory was mainly tested on active foragers and therefore its applicability to trap-building predators is poorly understood. The high sensitivity of trap-building predators to changes in their physical environment, combined with their limited movement capability, can lead to habitat specialization, reducing their utilization of alternative habitats. We studied density-dependent habitat selection in two pit-building antlions, differing in their habitat utilization spectrum. The habitat generalist, Myrmeleon hyalinus, inhabits and performs equally well in both sand- and loess-derived soils, although preferring the former, more productive coarse-grained soils. In contrast, the habitat specialist, Cueta lineosa, only inhabits fine-grained soils such as loess, while showing reduced foraging performance in coarse-grained sandy soils. We allowed larvae to select between these two soils, while manipulating con-specific density and initial stocking position. Irrespective of the initial stocking position, the number of M. hyalinus pits in the sand was positively correlated with the number of con-specific pits in the loess, implying that this species is a density-dependent habitat selector. Furthermore, these patterns of density-dependence were consistent with the expectations of ideal pre-emptive distribution (i.e., strong non-linearity in the distribution of antlions between soils with increased total density), suggesting that interference competition largely dictates habitat selection in this species. In contrast, the habitat specialist showed constant habitat selectivity, as neither con-specific density nor initial stocking positions influenced its habitat preference. Although mainly tested on active foragers, habitat selection theory can be applicable for trap-building predators, demonstrating how mechanisms operating at the individual level influence spatial distribution patterns.     

The Old Ladies of the Seed Harvester ant Pogonomyrmex Rugosus: Foraging Performed by Two Groups of Workers

We examined temporal polyethism in Pogonomyrmex rugosus, predicting a pattern of decreasing age from foragers to nest maintenance workers to individuals that were recruited to harvest a temporary food source. Nest maintenance workers were younger than foragers, as indicated by their heavier mass and lower mandibular wear. In contrast, recruited foragers were similar in mass to foragers but they displayed higher mandibular wear, suggesting that they were at least as old as foragers. Longevity estimates for marked individuals of these two latter task groups showed mixed results. Higher mandibular wear of recruited foragers suggests that they did not follow the normal sequence for temporal polyethism, but rather that they functioned as seed-millers, which should more quickly abrade their dentition. This would be the first demonstration of specialist milling individuals in a monomorphic seed-harvester ant.     

Why are population growth rate estimates of past and present hunter–gatherers so different?

Hunter–gatherer population growth rate estimates extracted from archaeological proxies and ethnographic data show remarkable differences, as archaeological estimates are orders of magnitude smaller than ethnographic and historical estimates. This could imply that prehistoric hunter–gatherers were demographically different from recent hunter–gatherers. However, we show that the resolution of archaeological human population proxies is not sufficiently high to detect actual population dynamics and growth rates that can be observed in the historical and ethnographic data. We argue that archaeological and ethnographic population growth rates measure different things; therefore, they are not directly comparable. While ethnographic growth rate estimates of hunter–gatherer populations are directly linked to underlying demographic parameters, archaeological estimates track changes in the long-term mean population size, which reflects changes in the environmental productivity that provide the ultimate constraint for forager population growth. We further argue that because of this constraining effect, hunter–gatherer populations cannot exhibit long-term growth independently of increasing environmental productivity.This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.