蝙蝠:麦田害虫的答案?

Despite being well known for their pest control abilities, bats remain understudied and misunderstood, and their numbers have been on the decline for various reasons. Now research is showing that these mammals may be invaluable to macadamia farmers, whose pest control costs are rising while their nut quality is dropping. Lindi Botha spoke to Dr Valerie Linden about bats’ potential to save the industry millions of rands.

蝙蝠:麦田害虫的答案?
在Macadamia Orchard中的侦察揭示了臭虫的巨大存在。通过正确的管理实践,可以通过蝙蝠控制这种害虫。Photo: Lindi Botha
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尽管有害虫控制应用增加,但似乎繁殖的臭虫群体困扰,南非的麦田行业每年遭到昆虫害虫损害的百万百万。这种损害与非妥疑核有关,这种情况是壳中壳中的麦田螺母被昆虫损坏,同时成熟在树上。

Many farmers have reacted by applying ever more pesticide, which has only served to exacerbate the problem as natural predators to harmful insects are also eliminated, detrimentally affecting the entire ecology within orchards.

One of South Africa’s largest macadamia production areas, Levubu in Limpopo, happens to be home to 14 bat species. This, coupled with the economic significance that bats could offer macadamia farmers, led Dr Valerie Linden, from the Centre for Invasion Biology at the University of Venda, to conduct research that could eventually see bats protected and nurtured by the agricultural community.

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“众所周知,蝙蝠在南非麦卡露达果园活跃,并归因于主要的昆虫害虫物种,如绿色蔬菜虫(内扎拉泼妇),澳洲坚果博勒(Cryptophlebia Ombrodelta),双察觉臭虫(Bathycoelia Natalicola)和荔枝蛾(C.Peltastica),“林登说。

“What we didn’t know was just how much of the pest insect population these bats consumed, which is what we set out to study.

“In Levubu, many other crops or even areas of natural bush are being removed and replaced with macadamias. The crop is highly valuable, so it’s an ideal species to study if you want to look at the economic impacts of the presence or absence of biocontrol agents such as bats. Macadamias are under high insect pressure, which was another criterion.

“We ultimately found that farmers could save as much as R76 300/ ha in reduced nut damage as a result of bats keeping stink bugs under control.”

林登认为,将蝙蝠的价值转换为兰特和美分将有很长的方式来保护这些哺乳动物。

“Many people are unaware of the benefits provided by bats as well as their general presence, so they’re hardly missed, and declines in their numbers aren’t noticed directly.”

她补充说,蝙蝠也慢慢繁殖,每年只有一个小狗,因此恢复人口可能需要比啮齿动物更长的时间。因此,让人们意识到他们的价值和他们提供的服务,以便每个人都有兴趣保护这些动物。

“害虫控制不仅适用于农业和食品生产,而且对于疾病控制,因为蝙蝠吃疟疾的蚊子。他们也是粉丝器和种子分散者。“

大自然是最好的
For the study, Linden created a scenario where bats and birds were absent from macadamia trees.

Cages were constructed around macadamia trees enclosed with nylon mesh net that would keep larger animals out, but would let insects through to gain access to the trees.

为了区分蝙蝠和鸟类的影响,有些笼子在夜间关闭,其他人在白天关闭,并一直关闭第三种。控制树根本没有封闭。林登然后监测对昆虫群体,产量和螺母质量的影响。

“我们还将树木与果园内部进一步的自然或半天然植被旁边比较了树木,远离任何自然栖息地。我通过使用蝙蝠探测器和每月昆虫昆虫的每月昆虫计数以及每季结束时的声学监测,通过声学监测监测蝙蝠活动,并在每个季节结束时评估质量和产量,识别不同昆虫造成的缺陷。

“我们发现蝙蝠和鸟类都作为生物控制剂的巨大影响。他们的缺席导致质量降低,产量降低了60%。“

Linden also found that the impact of bats as natural pest control in macadamias was higher in trees close to natural habitat than in trees away from any natural vegetation. Benefits could be seen up to 530m from the natural vegetation.

“虽然这些天然植被的斑块也可以产生问题,因为它们是猴子等作物攻略的栖息地,但我的结果表明,远离这些补丁的益处远远超过了缺点。通过蝙蝠和这些自然边缘附近的蝙蝠和鸟类的更高生物控制节省,这些天然边缘在学习区域上涨至R76 500,远远高于通过猴子袭击的测量损失,即R24 500。“

蝙蝠和鸟类均排除的围栏,生产最低的螺母,随后是排除的,然后夜间排除。

蝙蝠和鸟类的排斥了60% decrease in yield compared with the control. The exclusion of both bats and birds therefore resulted in an income loss of around R76 300/ ha. The reduced income losses for the exclusion of diurnal birds totalled around R60 200/ ha, and for bats and nocturnal birds about R37 000/ha.

为了进一步突出了蝙蝠的能力s to assist with pest control, Linden recorded bat numbers throughout the year and found that an increase in bats correlated with the macadamia nut season.

最高(3月和5月)和最低(11月和8月)在研究期间记录的蝙蝠的平均数重叠(12月至5月至5月底)和低(6月至11月底)昆虫害虫群的季节果园,蝙蝠活动几乎在旺季加倍。
creating a bat-friendly environment

While bats have proved their worth in macadamia orchards, keeping their numbers sufficiently high is a challenge. An ever-growing human population and related land use changes, especially agricultural intensification, have led to a threat of extinction of about one quarter of bat species globally.

林登指出,土地利用变化引起的栖息地失去是这种下降的主要驱动因素之一,而且有关非洲蝙蝠物种的栖息地偏好的特别缺乏了解。

“The importance of landscape features and connectivity within an agricultural landscape for bats has been proved. It’s therefore recommended that farmers increase or at least maintain the amount of natural vegetation around agricultural areas, considering the significantly higher pest control services. Other ecosystem services, such as pollination, could also be enhanced by natural vegetation and be compromised by its removal or isolation.”

Linden believes education is an important tool in protecting natural areas around agricultural land, highlighting the valuable benefits, which can outweigh its costs.

“让种植者了解威胁以及自然地区为他们的经济利益构成的经济利益是很重要的,因为他们可以在物种保护中发挥重要作用。”

管理蝙蝠
The proactive management of bat populations is indispensable to sustaining the ecosystem services they provide. This means that farmers need to follow a combination of practices, which include decreasing pesticide use, leaving natural habitats intact and erecting bat houses.

“众所周知,蝙蝠在有机农场上更活跃,因为它们对农药敏感,这不仅影响它们,而且杀死了他们的食物来源。蝙蝠严重依赖自然栖息地,如大型土着树,所以栖息地保护和连通性很重要。如果他们的自然栖息地消失了,那么蝙蝠也会。“

Linden cautions that while Levubu farmers are fortunate in that the bat diversity is particularly high in this area, she found evidence that clutter-feeding bat species, which are generally more sensitive to disturbances and pesticide application, are more or less absent from the orchards.

“So although bats are around the orchards, farmers need to be aware how management practices can affect natural predators.

“To further promote bird and bat populations and thereby potentially increase the value of biological control, artificial nesting and roosting sites can be provided to encourage bats to inhabit agricultural areas, where natural habitat is scarce. This can be more cost-efficient than pesticide treatments in keeping pest species under a certain threshold.”

Unfortunately, artificial roosts, such as bat houses, cannot entirely replace natural roosts, as they are suitable only for some species. Linden has found, however, that bat houses are a good way to establish large colonies of certain bats around orchards.

她建议农民在购买蝙蝠房间时要小心,并非所有人都适合。

“The most important aspect is durability. It can take up to five years for bats to occupy a house, so ideally your bat house must be able to last longer than that.”

She notes that while bats are not a complete solution to pest insect problems in orchards, and like any other predator cannot completely eliminate pests, they can control them effectively.

“If you can establish a healthy bat population on your farm, pest numbers and, with that, the need for pesticide, will go down. This, in turn, might increase bat activity in the orchards and pest numbers will decrease further.”

Email Dr Valerie Linden at[email protected]

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