Study suggests warmer temperatures could lead to upsurge in maize pests

By Sade Oguntola


World climatic changes are likely to worsen world’s food insecurity problems as the changes provide the warmer weather pests prefer. The warmer growing season temperatures and milder winters, a study from the Purdue University, said could allow some of these insects to expand their territory and produce an extra generation of offspring each year.


Dr. Noah Diffenbaugh, an associate professor of earth and atmospheric sciences who led the study, said though by projections, all the species studied were spreading into agricultural areas where they currently are not endemic, but the greatest potential range expansion was seen with the corn earworm, which is known to infest other high-value crops such as sweet corn and tomatoes.


The corn earworm is of particular concern because it is migratory and pesticide resistant. This global pest has developed resistant to several existing pesticides and adult moths are capable of being transported long distances in the jet stream to infest new crops. An effectively longer season, or more days exceeding their minimum temperature range, provides them with additional time to feed, mate and reproduce.


For countries like the United States that is the largest corn producer in the world and that contributes almost half of the world’s total production, this has a lot of economic implications, given that corn and corn syrup are used in common food items such as cereal and soft drinks, as well as being used as feed for livestock.


Meanwhile, any reduction in corn yields, from pests like corn earworm, could have substantial economic and social impacts, including higher food prices and reduced food supply. Losses due to insect pests, including the resources required to control them, is the biggest cost for corn production.
The study examined both the number of days warm enough for the pests to grow and the number of days cold enough to kill the pests, assuming the pests’ documented climate tolerances remain the same. This was to help tell what could happen in projected future climates.


The research team studied the potential end-of-the-century distributions of the corn earworm, Heliothis zea; the European corn borer, Ostrinia nubilalis; northern corn rootworm, Diabrotica barberi; and western corn rootworm, Diabrotica virgifera virgifera.


In addition, the International Institute of Tropical Agriculture in partnership with the Institute for Agricultural Research, Zaria, has developed new maize varieties to reduce annual grain losses in Nigeria, West and Central Africa for Agricultural Research, Zaria. The new maize varieties—IWDC2SynF2 (SAMMAZ 15) and TZLComp1Syn W-1 (SAMMAZ 16) — can significantly reduce the annual yield losses in maize production in Africa due to the infestation of Striga hermontica.


Striga, also known as witch-weed, attacks cereal crops with annual maize yield losses in the savannah regions estimated to reach $7 billion and with negative impact on the lives and livelihood of over 100 million people in Africa.


The parasitic plant is endemic in Africa and it constitutes the most important biotic constraint to maize production with infested areas in Africa estimated at between 21 million ha and 50 million ha.


IITA and its Nigerian partners say the release of the varieties, which took place in December, will boost farmers’ incomes and increase the production of maize in Nigeria. Dr. Abebe Menkir, IITA’s maize breeder said, “The results show great prospects for increased maize production in Nigeria and West and Central Africa in general.”According to him, “Several options are available for the control of Striga in maize, but the most economically feasible, safe, easily accessible and sustainable approach is the use of resistant or tolerant cultivars that the resource-poor farmers can cultivate solely or in combination with cultural management options as well as in rotations with legumes that elicit suicidal Striga germination.”



Nigerian Tribune