狗能嗅出柑橘業(yè)最具毀滅性的病原體威脅

狗能嗅出柑橘業(yè)最具毀滅性的病原體威脅

One of the most severe crop pandemics in modern times is that to citrus trees, caused by a bacterium that jumped from the animal to plant kingdom within the last 200 years. Once a tree is infected with the exotic pathogen, called huanglongbing (HLB), it will die. There is no cure, and the disease can spread fast. The only method to halt an entire crop collapse? Eliminate the tree.

現(xiàn)代最嚴(yán)重的農(nóng)作物流行病之一是柑橘樹，它是由一種細(xì)菌引起的，這種細(xì)菌在過去200年里從動(dòng)物王國跳到植物王國。一旦樹木被外來病原體黃龍病(HLB)感染，它就會(huì)死亡。目前還沒有治愈的方法，而且這種疾病可以迅速傳播。唯一能阻止作物全面崩潰的方法是什么?毀掉所有的樹。

"Proportionally, this epidemic has affected a larger proportion of the worldwide host population than most emerging zoonotic and botanical epidemics,” write the team in Proceedings of the National Academy of Sciences. "Originating in Asia in the previous century, HLB has spread to the majority of citrus-producing areas of the world, emerging throughout the Western Hemisphere with devastating results."

研究小組在《美國國家科學(xué)院院刊》上寫道:“從比例上看，這種流行病對全球宿主人口的影響比大多數(shù)新出現(xiàn)的人畜共患病和植物流行病更大。”“HLB起源于上個(gè)世紀(jì)的亞洲，現(xiàn)已傳播到世界上大部分的柑橘產(chǎn)區(qū)，并在整個(gè)西半球出現(xiàn)，帶來了災(zāi)難性的后果。”

Florida lost around 80 percent of its citriculture production and around 70 percent of its juice plants. The team warn that if not curtailed, the pathogen could destroy Florida’s citrus industry, previously the second largest in the world. This is nothing to scoff at: Citrus fruits are among the highest-value fruit crop for international trade, with oranges topping the list, followed by grapefruits, lemons, and limes.

佛羅里達(dá)損失了大約80%的柑橘生產(chǎn)和大約70%的果汁工廠。研究小組警告說，如果不加以限制，這種病菌可能會(huì)摧毀佛羅里達(dá)的柑橘產(chǎn)業(yè)。這并不是什么值得嘲笑的事情:柑橘類水果是國際貿(mào)易中價(jià)值最高的水果作物之一，其中橙子位居榜首，其次是葡萄柚、檸檬和酸橙。

"As a consequence, over the last 13 years, citrus industries in the United States alone have dedicated over $100 million to research of this new pathosystem with no imminent solution for HLB control," the team write.

“結(jié)果，在過去的13年里，僅美國的柑橘產(chǎn)業(yè)就投入了1億多美元來研究這種新的病理系統(tǒng)，而HLB控制還沒有迫在眉睫的解決方案，”該團(tuán)隊(duì)寫道。

The researchers instead turned to our favorite sniffers out there: detector dogs. They used Belgian malinois, German shepherds, hybrids between the two, and springer spaniels as "an ancient technology", as the team call them, to rapidly survey large plantings without the time-consuming and laborious work of collecting and analyzing samples by hand. The canine species were chosen for their instinct to hunt by odor, ability to traverse long distances, and their endurance.

研究人員轉(zhuǎn)而求助于我們最喜歡的嗅探犬:偵緝?nèi)Ｋ麄兪褂帽壤麜r(shí)馬里諾瓦犬、德國牧羊犬、兩者的雜交犬和施普林格西班牙獵犬作為“一項(xiàng)古老的技術(shù)”，正如研究小組所稱，他們可以快速地調(diào)查大面積的植物，而不需要手工收集和分析樣本，既耗時(shí)又費(fèi)力。之所以選擇犬科動(dòng)物，是因?yàn)樗鼈冇型ㄟ^氣味進(jìn)行捕獵的本能、長途跋涉的能力和耐力。

Detector canine 'Szaboles'. Image courtesy of Tim R. Gottwald

The "ancient technology" is a throwback to when canines were used by early humans as chemical detectors to hunt some 12,000 years ago. Now, the modern-day dog detectors have switched from animal prey to citrus pathogens, identifying infections with 99 percent accuracy up to weeks to years before a visual survey and molecular methods would have done so. The pet pooches were remarkably specific, discriminating HLB from other pathogens that could have distracted them. When two dogs were used, the detection accuracy was near 100 percent.

這項(xiàng)“古老的技術(shù)”可以追溯到大約12000年前，早期人類用犬科動(dòng)物作為化學(xué)探測器來狩獵?，F(xiàn)在，現(xiàn)代的狗狗探測器已經(jīng)從動(dòng)物獵物變成了柑橘類的病原體，在進(jìn)行視覺調(diào)查和分子方法之前的數(shù)周甚至數(shù)年，它們識別感染的準(zhǔn)確率高達(dá)99%。寵物狗非常專一，能區(qū)別HLB和其他可能分散它們注意力的病原體。當(dāng)使用兩只狗時(shí)，檢測準(zhǔn)確率接近100%。

Each canine went through 8 to 20 weeks of obedience and sensitization training, consisting of verbal praise and a toy reward for correct identifications. When a tree was infected with HLB, the dog would sit nearby and not move from the target until a reward was received. The number of false-positive errors was low, with 4 to 15 errors (0.0004 to 0.0015) per 950 to 1,000 trees per canine. The study suggests dogs are more effective and economical than current methods used for disease detection.

每只狗都經(jīng)過了8到20周的服從和敏感訓(xùn)練，包括口頭表揚(yáng)和對正確識別的玩具獎(jiǎng)勵(lì)。當(dāng)一棵樹感染了HLB，狗會(huì)坐在附近，直到收到獎(jiǎng)勵(lì)才會(huì)離開目標(biāo)。假陽性的錯(cuò)誤率很低，每950到1000棵樹每犬有4到15個(gè)錯(cuò)誤率(0.0004到0.0015)。這項(xiàng)研究表明，與目前用于疾病檢測的方法相比，狗更有效、更經(jīng)濟(jì)。

"Because canine detection is direct and immediate, this method has potential for use in real-time detection of bacterial, viral, and fungal exotic and endemic pathogens in field situations," the team write. "Deployment of canine teams for detection of CLas in commercial and research orchards began in Southern California in 2018 to 2019."

“因?yàn)槿惖臋z測是直接和及時(shí)的，這種方法有潛力在野外實(shí)時(shí)檢測細(xì)菌、病毒和真菌的外來和地方性病原體，”研究小組寫道。“2018年至2019年，南加州開始部署警犬團(tuán)隊(duì)，在商業(yè)和科研果園檢測CLas。”