What are microbial biopesticides?
Microbial biopesticides are a type of biological control. Biological control is defined as the use of natural
enemies (i.e. predators, parasitoids, pathogens and competing species) to reduce a pest population (Harper,
2006). Microbial biopesticides use microorganisms (i.e. bacteria, fungi, viruses and nematodes) that are
naturally pathogenic to specific crop pest insects.
Entomopathogens are natural (i.e. not synthetic) and in nature they cause natural epizootics which provide the
valuable ecosystem service of controlling insect numbers and preventing pest outbreaks. Scientists have
developed ways and are continuing to search for new ways to exploit this antagonistic relationship as a tool for
pest management. In 2003, biological control agents accounted for 1.72% of total usage for plant protection
products, of which 41% of spending was on microbial biopesticides (Harper, 2006).
There are three approaches used for application of microbial control agents (MCAs).
CHEMICAL PESTICIDES CAN NO LONGER BE RELIED UPON. In the past farmers have relied heavily
on the use of pesticides but pressure is now being put on the use of non-chemical alternatives. Many
chemical pesticides have been withdrawn from the market after government reviews due to concern
over their...
1.
Effects on human health.
Organophosphates for example
cause numerous minor illnesses
(e.g. vomiting, headaches and
abdominal pain) as well as more
serious illnesses (e.g. cancer
(namely Non-Hodgkin lymphoma
and Leukemia), neurological
dysfunction, miscarriages and
reduced birth weight) (McCauley
et al, 2006). Farmers and their
children are at highest risk.
2.
Short period of effectiveness due to pest
populations evolving natural resistance.
3.
Environmental impact. Widespread spraying
of chemicals causes considerable pollution
which can kill predatory birds and fish via
bioaccumulation along the food chain. The
organochlorine insecticide DDT for example,
has lead to the dramatic decline in peregrine
falcon and bald eagle populations because the
chemical causes thinning of the egg shell
which prevents successful hatching.
4.
Effect on non-target species. The broad
activity of pesticides can kill natural enemies
which control minor pests therefore
secondary pest outbreaks are common.
5.
Contamination of ground water
6.
Ability to reduce biodiversity
INSECT PESTS CAUSE DRAMATIC LOSSES IN CROP YIELDS. Over 10, 000 species of insects are crop
pests, however only 10% are major pests (Dhaliwal et al, 2010). These pests cause a massive constraint on
crop production. It is estimated that almost 14% of global yield for the eight major food and cash crops is
destroyed each year by insects (Table 1) (Dhaliwal et al, 2010). These losses occur despite the current pest
control strategies, including pesticide application and biological control. Improving pest management is
therefore key to improving yields. Furthermore, global warming is predicted to exacerbate the damage
caused by insects (Sharma, 2010). Pest outbreaks for example are likely to be more frequent as warmer
temperatures allow insects to expand their range and produce more generations in a year.
PEST CONTROL IS VITAL IN THE FIGHT TO FEED THE WORLD!
GLOBALLY, WE NEED TO PRODUCE MORE FOOD. Future food
security is becoming an increasing concern. Headlines in the news
are at present highlighting this issue as we witness food-related
riots in the Third World. Soaring food prices (Figure 1) for even
staple foods like rice have caused social unrest in countries such as
Egypt, Tunisia, Algeria, Mozambique and Indonesia. A report issued
in December 2010 by the UN's Food and Agriculture Organization
(FAO) has identified 29 counties in crisis that require external
assistance for food security. The FAO also reported that in 2010 just
under a billion people worldwide were undernourished (Figure 2).
Street Beggars in Ethiopia
THE SITUATION IS GOING TO GET WORSE. Concern about a global food crisis is based on the simple maths
that by 2050 global food production must increase by at least 70% to feed a global population expected to rise
from 6.2 billion (in 2010) to 9.2 billion, according to the US Census Bureau (FAO, 2009).
Meeting this increase poses a huge challenge. A challenge
that will be made harder to overcome by the impact climate
change is predicted to have on agriculture and the
implications of other factors including water shortage, land
degradation, crop disease, invasive species and pest damage.
MICROBIAL BIOPESTICIDES can form part of the solution as they offer effective pest control with
no harmful environmental effects.
Figure 1 FAO Food Price Indices for March 2011 (FAO, 2011)
Figure 2 FAO Hunger Map 2010: Prevalence of undernourishment in developing countries (FAO, 2010)