Title: Research highlights
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00071929/00003
 Material Information
Title: Research highlights
Uniform Title: Research highlights (East Lansing, Mich.)
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Bean/Cowpea Collaborative Research Support Program
Publisher: Michigan State University Bean/Cowpea CRSP
Place of Publication: East Lansing
Publication Date: 1984-
Subject: Beans -- Research -- Periodicals -- Africa   ( lcsh )
Beans -- Research -- Periodicals -- Latin America   ( lcsh )
Cowpea -- Research -- Periodicals -- Africa   ( lcsh )
Cowpea -- Research -- Periodicals -- Latin America   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
periodical   ( marcgt )
Statement of Responsibility: Michigan State University Bean/Cowpea CRSP.
Dates or Sequential Designation: Vol. 1, no. 1 (1984)-
General Note: Title from caption.
Funding: Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
 Record Information
Bibliographic ID: UF00071929
Volume ID: VID00003
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 13864898

Full Text

Michigan State University Bean/Cowpea CRSP

Vol. I No. 3 1984

Ardeshir Ghaderi, Editor

Fungal Diseases in Leafhopper Control
Brazil/Boyce Thompson Institute/Roberts

The economic and technological progress
achieved by Brazil in recent years has been
primarily in the South. In sharp contrast to
these well developed areas, the expansive
northeastern Brazil is severely depressed.
The principal industry of the region is ag-
riculture; however, insufficient and unpre-
dictable rainfall and low soil fertility com-
bine to greatly limit productivity. Most farms
are small and worked almost entirely by
hand; crop production is constrained to lit-
tle more than subsistence levels during even
the best of times. In adverse periods, such
as the past five drought-stricken years, the
people suffer near-starvation conditions.
In northeastern Brazil, as in other areas of
Latin America and subsaharan Africa with
similar climatic conditions, the hardy legume
Vigna unguiculata cowpeaa or black-eyed
pea) is a dietary staple, providing a large
percentage of the total protein consumed.
Cowpeas are able to tolerate the normal
harsh conditions of the long, hot, dry
growing season of interior northeast Brazil
and the excessive humidity of coastal areas.
But even under conditions which would
otherwise allow relatively good cowpea pro-
duction, yields frequently are greatly re-
duced by severe infestations of insect pests.
Application of chemical insecticides in trials
conducted by IITA, the international ag-
ricultural research center in Nigeria, de-
monstrated that it is possible to get up to
ten-fold increases in cowpea production.
Extensive use of pesticides, however, is ex-
tremely costly, even by United States' stan-
dards, and this factor alone (without consid-
ering the associated problems of insecticide

resistance and environmental contamina-
tion) makes this means of pest control totally
infeasible to Brazilian subsistence farmers.
To address these conditions, the Bean/
Cowpea Collaborative Research Program
(CRSP) supports a project of collaboration
between Boyce Thompson Institute (BTI)
and the National Center of Investigation for
Rice and Beans (CNPAF) of EMBRAPA, Brazil.
The project is a study of the development
and utilization of natural biological agents
for control of insect pests of beans and
cowpeas in northeastern Brazil. The incor-
poration of such agents into Brazilian bean/
cowpea integrated pest management sys-
tems is an attractive concept with considera-
ble potential. Several major advantages may
be realized:
1) Most importantly, biological control
agents could be obtained without expen-
diture of hard currency, since they could
be produced locally by government or
farmer organized associations using inex-
pensive raw materials (in some cases
using waste vegetable matter).
2) Possibilities exist for the establishment and
persistence of biological control agents
following their introduction into areas
where they did not previously exist -
thereby affording a natural level of pest
suppression and reducing the need for
regularly repeated pesticide applications.

3) Natural biological insect control agents
are notably safe compared to synthetic
chemical insecticides which may be
highly toxic to beneficial organisms, ac-

Funded through USAID/BIFAD Grant No. AID/DSAN-XII-G-0261

cumulate in food chains, and contami-
nate water and food supplies.
Research conducted under the Bean/
Cowpea CRSP during 1982 and 1983 em-
phasized the isolation, identification, and
characterization of insect pathogenic fungi
with biological control potential. The idea of
using naturally occurring microorganisms to
control insect pests is not new. Fungal
agents of insect diseases have been applied
for many years against a variety of pests
worldwide (for example, to control Colorado
potato beetles in Europe, sugarcane
spittlebugs in South America, and cornbor-
ers and pine caterpillars in China). Our re-
search effort in Brazil is directed toward
control of several important bean and
cowpea pests. However, the remainder of
this report will deal briefly with only one of
these insects which serves as a typical exam-
ple of the ongoing research.
Green leafhoppers (Empoasca species) are
not present in large numbers in all areas of

northeastern Brazil every year; however,
localized infestations frequently devastate
cowpea crops. Survey trips to Brazil in 1982
and 1983 discovered epidemics of two fungal
pathogens of this insect pest. These two
fungi (Hirsutella guyana and Erynia radicans)
and also a highly pathogenic isolate of
another species (Metarhizium anisopliae)
from the USDA collection of insect
pathogenic fungi maintained at Boyce
Thompson Institute on the Cornell Univer-
sity campus are being intensively studied to
determine their effectiveness as leafhopper
control agents. These investigations include
(1) epidemiological studies to identify the nec-
essary environmental and host conditions
for successful fungal infection, (2) biologi-
cal assays to determine lethal dose levels,
(3) microbiological culture studies to identify
important growth factors, (4) mass fermenta-
tion studies to develop efficient and inexpen-
sive methods for large-scale production of
infectious fungal material, (5) formulation



Plate 1: Family group hired to harvest cowpeas in Rio Grande do Norte, Brazil.
(Photo: D. W. Roberts)

research to develop fungal preparations
which retain their potency under prolonged
storage and which are easily handled and
applied in the field, and (6) small scale field
and screenhouse trials to evaluate the efficacy
of experimental formulations and to assess
the ability of the fungi to infect leafhoppers
under field conditions.
Considerable progress has been made,
particularly in the areas of biological assay
and mass production. Many difficult prob-
lems remain, however. The most challenging
are those created by the harsh climate of
northeastern Brazil. The fungal pathogens
mentioned above are similar in that they all
require moderate-temperature, high-
humidity conditions for reproduction (spore
production) and insect host infection. Dur-
ing the long, hot Brazilian summers, such con-
ditions exist for only a relatively short period
of the day from approximately dewfall in
the evening until sunrise. The high temper-
atures and low humidities which prevail

riare z: LeaTnopper (tmpoasca Kraemer) KIllea ana
attached to a cowpea leaf by the fungus
Hirsutella guyana. Rio Grande do Norte,
Brazil. (Photo: S.P. Wraight)

during the day inhibit fungal germination,
and solar radiation is lethal to the infectious
units (spores) of these fungi. Screenhouse
studies are therefore planned to determine
the optimal time and method of fungal ap-
plication against leafhoppers. Investigations
will also be aimed at developing formula-
tions which protect the fungus during the
hot, dry daytime periods, while enhancing
infection and development during the
cooler, more humid nights.
Insect pathogenic fungi have received
considerable attention in recent years, and a
number of researchers are seeking solutions
to the many problems currently impeding
their development and use as biological
control agents. We are confident that these
problems will eventually be overcome and
that, in time, fungal pathogens will be
utilized in legume integrated pest manage-
ment systems in northeastern Brazil and
similar agricultural regions of the world.

Plate 3: The leafhopper-pathogenic fungus Hirsutella
guyana growing on artificial medium in a
petri dish. (Photo: S.P. Wraight)

Plate 4: Conidia (infective spores) on phialids of the Plate 5: Same subject as P/ate 4.
leafhopper-pathogenic fungus Hirsutella
guyana. (Photo: S. P. Wraight)
guyana. (Photo: S. P. Wraight)

For further information contact:
Bean/Cowpea CRSP
200 Center for International Programs
Michigan State University
East Lansing, Michigan 48824-1035

Telephone: (517) 355-4693
Telex: 810-251-0737

An international community of persons, institutions,
agencies and governments committed to collectively
strengthening health and nutrition in developing
countries by improving the availability
and utilization of beans and cowpeas

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