Technologies for Overcoming Biotic Constraints

A veterinarian vaccinates a chicken in Afghanistan. Source: USAID

Diseases and insect pests rob the world of more than 40 percent of the attainable yield of the eight most important food crops, and invasive species threaten both crops and native biodiversity.

The most damaging weeds to overcome in these two regions include Striga (witchweed) in grain and legume crops in sub-Saharan Africa; Echinochloa, an herbicide-resistant weed in rice; and Phalaris minor, the major weed of wheat in South Asia. Farmers also face threats from viruses, including Cassava Brown Streak; Cucumber Mosaic Virus; African Cassava Mosaic Virus; and Cotton Leaf Curl, as well as major insect pests such as weevils and stem, fruit, and grain borers, and insects that serve as vectors for disease transmission.

There are several promising technologies to mitigate biotic threats. All of these are listed as Tier I, as they have been proven effective but not yet made available for application in the two regions.

Tier I Technologies

Plant-mediated gene silencing

Using plant-mediated gene silencing, scientists induce plants to transfer pieces of genetic material to other organisms, targeting and interfering with the interactions between plants and their pests at the genetic level. This approach takes advantage of the recently discovered powerful molecules known as small RNA, which play a role in plant development and resistance to stress. Plant-mediated gene silencing has shown promise for control of viruses, nematodes, and certain insects.

Biocontrol and biopesticides

Approaches involving biocontrol and biopesticides focus on using natural means to fight diseases, pests, and weeds. Biocontrol involves the release of a pest’s specific natural enemies to control its population. Biopesticides are types of pesticides that use toxins that are naturally produced by some organisms, instead of synthetically-produced chemicals.

Disease-suppressive soils

The use of disease-suppressive soils involves management practices that encourage crop-associated microbial communities that naturally reduce plant diseases and pests. These practices might include manipulating carbon inputs, using crop rotation sequences that increase the presence of beneficial organisms, or inoculating the soil with disease-suppressive microorganisms.

Animal vaccines

Vaccinating animals against common diseases could greatly improve livestock productivity in the two regions. A range of approaches to vaccine development could be supported, from attenuated bacteria (bacteria whose virulence has been reduced) to DNA vaccines (in which an animal is injected with genetically engineered DNA to produce a specific immune response). The control of diseases such as brucellosis, leptospirosis, bovine virus diarrhea and other respiratory and intestinal diseases in young, preweaning animals could significantly improve the long-term productivity of important livestock animals in the two regions.