As Diana Parsell writes, about 35 percent of the worldâs ice-free land is now under cultivation, up from a minuscule 7 percent in the year 1700. And humans are continually improving the very crops we grow, she writes: in the last 40 years, farmers have doubled their yield while planting just 12 percent more land.
Perhaps the most controversial way we improve crop yields - genetic modification - just absorbed a dose of bad news yesterday in Nature Biotechnology. Scientists from the University of Arizona reported the first case of an insect pest evolving resistance to "transgenic" cotton plants that make a pesticide called Bt. Say what you want about whether evolution is real â this change took about seven years.
Genetic engineering is a touchstone issue: it's anathema to many, while to others it's our crowded worldâs only practical hope. Though GM crops are banned in the European Union, Bt-producing cotton and corn have flourished on more than 400 million acres since they were first planted in 1996, the study reports. The immense planted area created what biologists call a strong selective pressure, favoring the survival of any pests with resistance to Bt and speeding evolution of the trait.
To be fair, Bt is a model pesticide thatâs been used widely since the 1950s. Far different from the likes of DDT, the chemical is produced organically, by a bacterium called Bacillus thuringiensis, and it is very specific, affecting only certain groups of insects. Most other animals can ingest it without so much as a hiccup. By genetically engineering plants to produce Bt instead of scattering it from the wings of a cropduster, farmers can avoid the collateral damage that comes from spraying plants other than their crop. And, the authors point out, resistance has so far appeared in only one of many pest species, and only in about a dozen small localities.
Still, this week's news resurrects an old hobgoblin of pesticide use. Barely a decade after the first delighted reports of DDTâs effectiveness â and the awarding of the Nobel prize to its developer â the first reports of resistance trickled in. Ever since we've seen an escalating arms race between ingenious people and adaptable insects. Already the new articleâs authors are pointing to a new generation of Bt-engineered crops â these now produce two varieties of Bt to boost their effectiveness. But the writing is on the wall: resistance is inevitable.
Interestingly, a separate article in the journal reports new efforts to begin to evaluate the effect of pesticide-producing crops on ânontargetâ? insects - the innocent bystanders and the good guys. A laudable effort, but perhaps regrettable that itâs happening 10 years after the first mass plantings. The question with genetic engineering remains: Can our knowledge of what weâre doing keep up with how fast weâre doing it?
"Diana Parsell anasema: ""Kama ilivyo kwa miaka ya 1700, asilimia 35 ya ardhi ya dunia isiyo na barafu sasa inamilikiwa na wakulima." """Wanaume wanaendelea kuboresha mazao yetu,"" anaandika, ""kwa miaka 40 iliyopita, wakulima wameongeza uzalishaji wao mara mbili huku wakipanda ardhi kwa asilimia 12 tu zaidi." Labda njia yenye utata zaidi tunayoongeza mavuno ya mazao - mabadiliko ya maumbile - ilichukua kipimo cha habari mbaya jana katika Bioteknolojia ya Asili. Wanasayansi kutoka Chuo Kikuu cha Arizona wameripoti kesi ya kwanza ya wadudu wadudu wanaobadilisha upinzani kwa mimea ya pamba ya "transgenic" ambayo hufanya dawa ya kuua wadudu inayoitwa Bt. Sema unachotaka kuhusu kama mageuzi ni ya kweli - mabadiliko haya yalichukua miaka saba hivi. Uhandisi wa maumbile ni suala la msingi: ni laana kwa wengi, wakati kwa wengine ni matumaini pekee ya vitendo ya ulimwengu wetu uliojaa watu. Ingawa mazao ya GM yamepigwa marufuku katika Umoja wa Ulaya, Bt-kuzalisha pamba na mahindi yamefanikiwa katika zaidi ya ekari milioni 400 tangu yalipandwa kwa mara ya kwanza mnamo 1996. "Uwanja huo mkubwa uliotengenezwa na mimea uliunda kile wanajimu wanachoita ""ushindi mkubwa wa kuchagua,"" ukifaidisha kuokoka kwa wadudu wowote wenye upinzani wa Bt na kuharakisha mageuzi ya tabia hiyo." Bt ni dawa ya kuua wadudu ambayo imekuwa ikitumika sana tangu miaka ya 1950. Kinyume na DDT, kemikali hiyo hutengenezwa kwa njia ya kikaboni na bakteria inayoitwa Bacillus thuringiensis, na ni maalum sana, ikiathiri vikundi fulani tu vya wadudu. Wanyama wengine wengi wanaweza kuitumia bila hata kukosa. Kwa kuunda mimea kwa njia ya maumbile ili itokeze Bt badala ya kuisambaza kutoka kwa mabawa ya cropduster, wakulima wanaweza kuepuka uharibifu wa dhamana unaotokana na kunyunyizia mimea nyingine mbali na mazao yao. Kwa mujibu wa watafiti, hadi sasa, aina moja tu ya wadudu imeweza kuathiriwa na ugonjwa huo, na ni katika maeneo kadhaa tu. Hata hivyo, habari za juma hili zinafufua wazo la zamani la matumizi ya dawa za kuua wadudu. Karibu miaka kumi baada ya ripoti za kwanza za kufurahisha za ufanisi wa DDT na tuzo ya Nobel kwa msanidi programu, ripoti za kwanza za upinzani zilikuja. Tangu wakati huo tumeona mbio za silaha zinazozidi kuongezeka kati ya watu wenye akili na wadudu wanaoweza kubadilika. "Wanahabari wa jarida hilo wametoa taarifa kwamba ""kijana kipya cha mazao ya Bt-engineered sasa hutengeneza aina mbili za Bt ili kuongeza ufanisi wao.""" Lakini maandishi ni juu ya ukuta: upinzani ni lazima. Kwa kushangaza, makala tofauti katika jarida hilo inaripoti juhudi mpya za kuanza kutathmini athari za mazao ya kuzalisha dawa za kuua wadudu kwenye anontarget. wadudu - watazamaji wasio na hatia na watu wazuri. Ni jambo la kusikitisha, lakini ni jambo la kusikitisha kwamba ni miaka kumi tu baada ya kupandwa kwa mimea hiyo. Swali la uhandisi wa maumbile linabaki: Je, maarifa yetu ya kile tunachofanya yanaweza kushikilia kasi ya jinsi tunavyofanya hivyo?