Sterile Radioactive Bugs Arrive in Croatia


A sterile radioactive kibbutz bug (Image PD by FAO)

Why did a kibbutz in Israel ship 380 million sterile, radioactive fruit flies to Croatia? That might be the most unusual introduction this blog has ever used. Here’s the backstory…

Ceratitis capitata – the lovely but insidious Mediterranean Fruit Fly – is indigenous to the fruit belt surrounding the Mediterranean Sea. This includes Croatia. Normally, the Medfly does not wander far, so it spreads slowly. Unless it’s boxed up in a crate of tangerines. Or figs, apples, peaches, blueberries, pomegranates, grapefruit, or some other wormy but nutritious carton of fruit. That’s how the Medfly reached the States, New Zealand, Chile, and (I think) Australia. In Chile, New Zealand, California, Texas, and Florida, the bug was successfully eradicated. Hawaii is still fighting it. If you don’t like worms in your oranges, it needs fought. The bug’s life cycle prompts it to poke holes into ripening fruit and deposit eggs under the fruit’s skin. The eggs hatch and the larvae (worms) eat, grow, and pupate. Even those of us who are free-range omnivores find the results a bit disgusting.

Not fussy – Medfly larvae enjoy a healthy variety of fruit
– including peaches and figs.

The Medfly can be sprayed into oblivion. That’s how California eventually ridden itself of the scourge. Back in 1989, Governor Jerry Brown resisted aerial spraying on environmental principles. He authorized a ground assault, but the Medfly moved ahead of the program. Reluctantly (and almost too late), Brown agreed on blanket sprays which finally destroyed the fruit flies. (By the way, Brown is again governor. He is 76 years old now. He took over a bitterly divided, bankrupt state (only partly due to Arnold the ex-terminator, who was formerly in charge). California, under Brown, has recovered remarkably. There is finally a government surplus – The Economist says Brown is “so tight-fisted he is not above eating off other people’s plates.” Potentially a bit disgusting, but I digress.) In the end, helicopters sprayed malathion at night while the California National Guard inspected vehicles fleeing infested areas. Later, entomologists released sterile Medflies to seduce any holdout Ceratitis capitata.

This brings us back to Croatia and the friendly kibbutz. In 1934, Jewish settlers from Germany began the Sde Eliyahu religious colony. They built their stockade and tower settlement near the Sea of Galilee at 200 metres (660 feet) below sea level where malaria swamps and summer heat affected the early settlers and their precarious crops. They persevered, transforming their worthless tract of land into an agricultural oasis. Today the kibbutz and its 750 residents are entirely dependent on farm-related activities. Here is what Sde Eliyahu says about itself: “Many of our field crops and fruit are special in that they are cultivated according to the principles of organic agriculture. We were real pioneers in this sphere in Israel fighting for the exclusion of toxic fertilizers and sprays. To replace the latter, natural enemies of pests have to be found and activated.” Pursuing natural solutions led to the establishment of BioBee, which is mainly involved in bumblebee pollination within greenhouses, and Bio-Fly, which raises indigenous Mediterranean fruit flies and sterilizes them.

Bio-Fly, a subsidiary of BioBee, was founded “for the purpose of developing and supplying biological control solutions for the Mediterranean fruit fly (Medfly) and other pests, using the Sterile Insect Technique,” according to the outfit’s website. The newspaper Haaretz says that the Israeli Atomic Energy Commission supervises the radioactive sterilization of the fruit flies while the kibbutz has a collaborative agreement with the Palestinian Authority, Jordan, and several Mediterranean governments for the distribution of the sterile flies. The company has a mass rearing facility and supplies sterilized male pupae, as well as sterile male flies for dispersal in agricultural fields. The latest swarm of flies were scattered along the border areas of Croatia and Bosnia. Normally, about 15 million sterilized pupae are produced each week at Bio-Fly. The sale to Croatia was over a third of a billion flies, so perhaps production has ramped up recently. (The 380 million flies were weighed, not individually counted.) By the way, the reason that only male fruit flies are sold is that it prevents a potential disaster if some flies are not effectively sterilized – no egg-layers are shipped abroad. The sterile males successfully mate with indigenous females who then remain infertile their entire week-long adult life.

Croatian fruit and veggie stand (photo – Miksha)

I was surprised that the Croatian tourist haven has a big tropical fruit industry. The coast is mostly craggy with mountains that encroach upon the sea. Almost everywhere along the coast, there isn’t much more than a skinny (but inviting) beach. But when I approached the Croatian coast from Sarajevo, driving south through Bosnia, a friend and I found ourselves on the broad Neretva Delta – a warm lowlands of rich soil and dense gardens and groves. It was quite a switch from the barren stone-filled hills to the north. Until the moment Neretva’s river valley opened before me, I was unaware of Croatia’s huge citrus industry. But as a Mediterranean country, Croatia’s burgeoning fruit-producing area suffers from the Medfly. (For more, and some great pictures, see the UN’s FAO report about Croatia’s fruit fly pests.)

Despite the flies, I was enthralled with the orange groves – something I missed since my Florida beekeeping days. Seeing all these small acreages owned by independent farmers who peddle their fruits and veggies at roadside stands was a slightly nostalgic trip back in time. I didn’t see any honey bees in the groves, but my trip was in October, not March, so the trees were not blooming. Migratory beekeepers would have moved their colonies north in early summer. The bees would not have been back until perhaps November. But when they did return, the beekeepers would not have to deal with clouds of malathion drifting over their bees, thanks to 380,000,000 imported radioactive male fruit flies.

Croatia’s fruit delta, along the Neretva River (photo – Miksha)

About Ron Miksha

Ron Miksha is a bee ecologist working at the University of Calgary. He is also a geophysicist and does a bit of science writing and blogging. Ron has worked as a radio broadcaster, a beekeeper, and Earth scientist. (Ask him about seismic waves.) He's based in Calgary, Alberta, Canada.
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