Source: NORTH DAKOTA STATE UNIV submitted to
MECHANISMS OF HOST-PLANT SELECTION IN THE WHEAT MIDGE
 
PROJECT DIRECTOR: Harris, M. O.
 
PERFORMING ORGANIZATION
SCHOOL OF NATURAL RESOURCE SCIENCES
NORTH DAKOTA STATE UNIV
FARGO,ND 58105
 
NON TECHNICAL SUMMARY: The wheat midge attacks developing wheat kernels and is a serious pest in North America, Europe and Asia. For related midges, such as the Hessian fly and rice gall midge, host plant resistance has, for many decades, been an effective means of pest management. For the wheat midge, success in finding host-plant resistance eluded scientists until recently when Canadian researchers reported the discovery of a highly effective resistance that causes the death of wheat midge larvae before they establish a feeding site. This newly discovered resistance is conferred by a single gene. Within the next 3-5 years, it is anticipated that common and durum wheat cultivars, all carrying this single resistance gene, will be deployed across the Northern Plains of North America. There are concerns that the wheat midge will overcome this resistance gene through evolutionary modification. Combining, within a single wheat cultivar, traits that kill larvae with traits that reduce the number of eggs placed on the plant by the adult female might provide more sustainable control of the wheat midge. We will explore the potential for reducing egg numbers by studying fundamental aspects of the oviposition behavior of the wheat midge. Specific research objectives are to determine whether wheat midge females 1) locate wheat heads using odor cues and 2) respond to chemical and tactile traits of wheat heads during on-plant examining behaviors.
 
OBJECTIVES: Determine if female wheat midge exhibit upwind flight when stimulated by volatile chemicals from wheat heads. Quantify behavioral responses of mated females to high- and low-ranked grasses. Develop models of wheat heads that can be used for future testing of plant stimuli
 
APPROACH: To determine if wheat midge females orient to volatile chemicals from wheat heads, females will be tested in a wind tunnel containing wheat plants with and without wheat heads. Females will be scored for upwind flight, approach and landing. To quantify responses to high- and low-ranked grasses, foraging behavior of mated females will be quantified in arenas that contain both types of grasses. Using focal animal sampling, we will score time of arrival on the head, examining behaviors, and flight. To develop models of wheat heads that can be used for future testing of plant chemical stimuli, we will make extracts of wheat heads, apply extracts to simple models of wheat heads, and observe females foraging in arenas containing these models.
 
CRIS NUMBER: 0193542 SUBFILE: CRIS
PROJECT NUMBER: ND05900 SPONSOR AGENCY: CSREES
PROJECT TYPE: NRI COMPETITIVE GRANT PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Sep 1, 2002 TERMINATION DATE: Aug 31, 2005

GRANT PROGRAM: ENTOMOLOGY/NEMATOLOGY
GRANT PROGRAM AREA: Plant Systems

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
211311011304.2100%

CLASSIFICATION HEADINGS
KA211 - Insects, Mites, and Other Arthropods Affecting Plants
S3110 - Insects
F1130 - Entomology and acarology
G4.2 - Reduce Number and Severity of Pest and Disease Outbreaks


RESEARCH EFFORT CATEGORIES
BASIC 50%
APPLIED 50%
DEVELOPMENTAL (N/A)%

KEYWORDS: wheat; grasses; cecidomyiidae; behavior; host selection; plant insect relations; chironomidae; insect behavior; insect ecology; plant insect resistance; insect genetics; genes; females; insect flight; volatile substances; crop pest models; insect larvae; mortality; insect physiology; defense mechanisms

PROGRESS: Sep 1, 2002 TO Aug 31, 2005
Our aim was to quantify the oviposition behaviour of wheat midge females on low-ranked versus high-ranked grass heads. The high-ranked type was Roblin hard red spring wheat (Triticum aestivum), with the seed head at an early stage of development, i.e. pre-anthesis. The three low-ranked plant types were 1) post-anthesis Roblin, 2) pre-anthesis Key hard red spring wheat, and 3) pre-anthesis Robust barley (Hordeum vulgare). The three low-ranked types were chosen because they or closely related genotypes have consistently received fewer eggs in the field and/or laboratory (Barnes, 1956; Ding & Lamb 1999; Lamb et al., 2000; 2003). Observations of mated females were conducted in a greenhouse during the months when wheat midge adults are present in fields (mid-June to mid-August) and during hours of the day when females begin host-finding and oviposition, i.e., the 1 to 1.5 hours preceding and following sunset. The null hypothesis was that wheat midge females exhibit the same behaviour on seed heads of the four grass types. In addition to testing this hypothesis, several tests were conducted to develop methods for observing the behaviour of individual females. We first used scan sampling to identify important units of behavior and their incidence on high- versus low-ranked heads and then used observations of females landing in choice tests and focal animal sampling to determine when and how (cues) females distinguish head types. Results showed that females behave quite differently on low- versus high-ranked seed heads but distinguish head types only after landing and examining the surfaces of modified leaves. We propose that females detect surface chemical cues using their antennae and/or chemoreceptors surrounding the ovipositor.

IMPACT: 2002-09-01 TO 2005-08-31 The wheat midge is an important pest of wheat in the Great Northern Plains. Recently an effective resistance gene, Sm1, was identified by Canadian researchers and currently is being deployed in both bread and pasta wheat cultivars. A concern is that wheat midge will adapt to Sm1, rendering this highly effective management tool useless. To prevent wheat midge adaptation, it has been proposed that the Sm1 trait be deployed with a plant trait that inhibits oviposition by the adult female. We have developed techniques for studying the oviposition behavior of the wheat midge female and quantified behavior on seed heads that are less stimulatory to oviposition. Our results will contribute to future studies on the impact of wheat chemical cues on oviposition, with the ultimate aim being to identify a plant trait for reduced oviposition useful for plant breeding programs.

PUBLICATION INFORMATION: 2002-09-01 TO 2005-08-31
No publications reported this period

PROJECT CONTACT INFORMATION
NAME: Harris, M. O.
PHONE: 701-231-6445
FAX: 701-231-8557