The effects of drought and herbivory on plant-herbivore interactions across 16 soybean genotypes in a field experiment
Abstract As the Earth's climate continues to change, drought and insect population outbreaks are predicted to increase in many parts of the world. It is therefore important to understand how changes in such abiotic and biotic stressors might impact agroecosystems. The plant stress hypothesis pr...
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| Published in | Ecological entomology Vol. 38; no. 3; pp. 290 - 302 |
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| Main Authors | , , |
| Format | Journal Article |
| Language | English |
| Published |
Oxford, UK
Blackwell Publishing Ltd
01.06.2013
Blackwell Wiley Subscription Services, Inc |
| Subjects | |
| Online Access | Get full text |
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| Summary: | Abstract
As the Earth's climate continues to change, drought and insect population outbreaks are predicted to increase in many parts of the world. It is therefore important to understand how changes in such abiotic and biotic stressors might impact agroecosystems.
The plant stress hypothesis predicts that, owing to physiological and biochemical changes, plants experiencing drought will be more susceptible to insect herbivory, which could have synergistic negative effects on plant performance. By contrast, the plant vigor hypothesis predicts that insects will preferentially feed on fast‐growing vigorous plants.
These hypotheses were tested in a field experiment using 16 soybean (
Glycine max
(
L
.)
M
err.) genotypes to determine: (i) the combined effects of drought and herbivory on plant performance; (ii) the impact of drought on soybean resistance to herbivores; and (iii) how genetically variable phenotypic traits in soybean correlate with these responses.
It was found that drought had a greater effect on soybean performance than herbivory, and drought and herbivory did not interact to impact on any measure of plant performance. Drought caused decreased insect herbivory on average, suggesting that the plant vigor hypothesis is consistent with the effects of drought stress on soybean resistance to leaf‐chewing insect herbivores. This conclusion is further supported by genotypic correlations which show that plant growth rate is positively correlated with the amount of herbivory plants received.
These results suggest that, although the effects of climate‐associated changes in drought and herbivory will have negative effects on soybean, these potential effects are quantifiable with simple experiments and can be mitigated through continued breeding of varieties that are tolerant and resistant to these abiotic and biotic stressors. |
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| Bibliography: | ark:/67375/WNG-R8RBWKZ1-6 ArticleID:EEN12017 NC State University (RG, MTJJ) USDA-ARS (TEC) istex:B2EB5314BCC5624512F26EB21E68C9955131836B Fig. S1. Figures illustrating experimental setup of field experiment. (A) A block set up with four rows down representing four maturity groups, and six rows across with the central four rows representing different genotypes within a maturity group; the two outermost rows represent a border genotype of the same maturity group. Entire blocks experienced either suppressed insects or ambient plus added insect herbivory, crossed with suppressed water (drought) or water irrigation to mimic typical ambient conditions. (B) Dripperline attached to PVC at the top of a block to deliver water to irrigated blocks. (C) Dripperline in U-formation at the bottom of blocks allowed delivery of water to all plants. (D) Plastic sheeting over a block to control rainfall; the field was sloped slightly downwards in the direction of the photograph, such that water quickly ran off the plastic to the end of the block. Water above the block was diverted with a trench that is partially visible towards the bottom of the photograph.Table. S1. Genotype information including genotype means of phenotypic traits and herbivory in each treatment.Table. S2. Monthly precipitation (cm) measured at the Lake Wheeler Field Laboratory weather station during the experiment in 2010 (June-November). Data presented include monthly total, deviation from the monthly mean, greatest amount of precipitation received in a 24-h period and the day of the month on which that occurred, plus the number of days during each month that 0.25, 1.25, and 2.5 cm or more precipitation fell in 24 h. Note that, although September experienced much higher than average precipitation, most of this occurred at the end of the month.Table. S3. Effects of drought and soybean genotype on herbivore performance in a detached leaf no-choice bioassay. We used two generalist feeding caterpillars, Helicoverpa zea and Spodoptera exigua and recorded their biomass gain after 7 days of growth starting from a freshly hatched first-instar neonate caterpillar. Caterpillar mass was analysed using the same model as described for percentage herbivory, while we used generalized linear models with a binomial distribution and a logit link function when analysing survival. Because the maximum likelihood model only converged when drought and maturity groups were included in the model (Model 1), we used generalized linear mixed models and pseudo-likelihood statistics to assess the effects of genotype in relation to drought (Model 2; see Methods) with significance tests calculated according to log-likelihood ratio tests. NSERC Canada ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
| ISSN: | 0307-6946 1365-2311 |
| DOI: | 10.1111/een.12017 |