Will there be a global famine in 2050? Crops will be overwhelmed by pests in the next 30 years, scientists warn

Another of the "coming shortage" scares that Greenies often resort to, none of which have ever come true.  The scare below  is sheer speculation.  To prove spread they needed similar population counts at two different dates.  But they did not have that.  All they had was "historical observation dates" for a minority of their species.  Anyway, genetic engineering techniques are alrady reducing pest loads and should continue to do so.  That is why Greenies are trying to ban it

Many of the world's most important crop-producing countries will be fully saturated with pests by the middle of the century if current trends continue, a study has found.

More than one-in-ten pest types can already be found in around half the countries that grow their host crops.

And if this spread advances at its current rate, scientists fear that a significant proportion of global crop-producing countries will be overwhelmed by pests within the next 30 years.

The research from the University of Exeter was published in the journal Global Ecology and Biogeography.


Experiments by British academics have found that GM insects could be used to wipe out fruit fly pests that damage crops such as oranges, peaches, apples and pears.

Genetically modified versions of the Mediterranean fruit fly were created earlier this year using controversial technology developed by the UK bioscience company Oxitec.

Millions of male GM flies have been created in the laboratory to include a gene which means that when they mate with wild females, any resulting female larvae die before reaching maturity.

The resulting fall in the number of female fruit flies should, in theory, lead to a collapse in the total population which will mean less damage is caused to food crops.

Oxitec has promoted the technology as an alternative to the use of harsh chemical pesticides to protect food crops and so boost yields and has held talks with UK government agencies to run trials in this country.

It describes the patterns and trends in the spread of crop pests, using global databases to investigate the factors that influence the number of countries reached by pests and the number of pests in each country.

Crop pests include fungi, bacteria, viruses, insects, nematodes, viroids and oomycetes.

'If crop pests continue to spread at current rates, many of the world's biggest crop producing nations will be inundated by the middle of the century, posing a grave threat to global food security,' said Dr Dan Bebber of the Biosciences department at the University of Exeter.

The study identifies the pests likely to be the most invasive in coming years, which includes three species of tropical root knot nematode whose larvae infect the roots of thousands of different plant species.

Another, Blumeria graminis, is a fungus that causes powdery mildew on wheat and other cereals.

And the Citrus tristeza virus (given its name meaning 'sadness' in Portuguese and Spanish by farmers in the 1930s) is also a threat, having reached 105 of 145 countries growing citrus by the year 2000.

Fungi lead the worldwide invasion of crops and are the most widely dispersed group, despite having the narrowest range of hosts.

The study looked at the current distributions of 1,901 crop pests and pathogens and historical observations of a further 424 species.

Significant use was made of historical CABI (Centre for Agriculture and Biosciences International) records, which document crop pests and diseases around the world from 1822 to the present day.

'By unlocking the potential to understand the distribution of crop pests and diseases, we're moving one step closer to protecting our ability to feed a growing global population,' said Dr Timothy Holmes, Head of Technical Solutions at CABI's Plantwise Knowledge Bank.

'The hope is to turn data into positive action.'

It supports the view of previous studies that climate change is likely to significantly affect pest pressure on agriculture, with the warming Earth having a clear influence on the distribution of crop pests.

The authors also describe the global game of cat-and-mouse as crops are introduced to pest free regions and briefly thrive, before their pursuers catch up with them.

Professor Sarah Gurr of Biosciences the University of Exeter added: 'New, virulent variants of pests are constantly evolving.

'Their emergence is favoured by increased pest population sizes and their rapid life-cycles, which force diversified selection and heralds the appearance of new aggressive genotypes.

'There is hope if robust plant protection strategies and biosecurity measures are implemented, particularly in the developing world where knowledge is scant.

'Whether such precautions can slow or stop this process remains to be seen.'


The global spread of crop pests and pathogens

By Daniel P. Bebber et al.



Current country- and state-level distributions of 1901 pests and pathogens and historical observation dates for 424 species were compared with potential distributions based upon distributions of host crops. The degree of ‘saturation’, i.e. the fraction of the potential distribution occupied, was related to pest type, host range, crop production, climate and socioeconomic variables using linear models.


More than one-tenth of all pests have reached more than half the countries that grow their hosts. If current trends continue, many important crop-producing countries will be fully saturated with pests by the middle of the century. While dispersal increases with host range overall, fungi have the narrowest host range but are the most widely dispersed group. The global dispersal of some pests has been rapid, but pest assemblages remain strongly regionalized and follow the distributions of their hosts. Pest assemblages are significantly correlated with socioeconomics, climate and latitude. Tropical staple crops, with restricted latitudinal ranges, tend to be more saturated with pests and pathogens than temperate staples with broad latitudinal ranges. We list the pests likely to be the most invasive in coming years.

Main conclusions

Despite ongoing dispersal of crop pests and pathogens, the degree of biotic homogenization of the globe remains moderate and regionally constrained, but is growing. Fungal pathogens lead the global invasion of agriculture, despite their more restricted host range. Climate change is likely to influence future distributions. Improved surveillance would reveal greater levels of invasion, particularly in developing countries.


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