Abstract
Abstract Defoliation by the alfalfa weevil ( Hypera postica Gyllenhal) results in a direct reduction in yield of alfalfa ( Medicago sativa L.). Indirect responses to insect feeding may partially compensate for direct losses or cause further reductions in yield and feed quality. The purpose of this study was to identify indirect responses of alfalfa to weevil defoliation. We studied the effects of the alfalfa weevil on (i) root reserves, as measured by total nonstructural carbohydrates (TNC) in the taproot, (ii) morphological rate of development, and (iii) canopy structure. Alfalfa weevil defoliation produced statistically significant effects on all three factors. When the peak of the undisturbed larval population was about three/stem, TNC levels were reduced by up to 0.14 metric ton/ha while defoliation occurred. After the larval population declined, there was recovery growth and TNC yields reached levels up to 0.09 metric ton/ha higher than where weevils were controlled. The crossover from lower to higher TNC levels was associated with delayed morphological development and a prolonged TNC accumulation period where damage occurred. When alfalfa was cut before the larval population reached a peak, TNC levels were reduced during the regrowth period. Larval populations higher than two/stem reduced canopy height and leaf percentages during defoliation. During the post‐defoliation recovery period, moderately damaged plants increased in leaf percentage and produced more branches than lightly defoliated plants. However, the moderately defoliated plants remained shorter and there were resulting large differences in canopy structure. These findings showed a wide range of indirect effects of insect defoliation on alfalfa growth, and they should be considered in evaluating insect damage to the crop.
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Claims 9
Claim · model-written summary
Weevil defoliation reduced alfalfa root TNC by up to 0.14 metric ton/ha during feeding.
- Taxon
- alfalfa
Medicago sativae1 - Treatment
- defoliatione2
- Interactor
- alfalfa weevil
Hypera posticae0pest - Outcome
- TNC levelse2
- Direction
- reducede2
- Value
- 0.14 metric ton/hae2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa weevil ( Hypera postica Gyllenhal)”
e1“alfalfa ( Medicago sativa L.)”
e2“TNC levels were reduced by up to 0.14 metric ton/ha while defoliation occurred.”
Claim · model-written summary
After larval decline, TNC yields rose up to 0.09 metric ton/ha above weevil-controlled plots.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- larval populatione2
- Interactor
- alfalfa weevilHypera posticae0pest
- Outcome
- TNC yieldse2
- Direction
- highere2
- Value
- 0.09 metric ton/hae2
- Comparator
- where weevils were controllede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa weevil ( Hypera postica Gyllenhal)”
e1“alfalfa ( Medicago sativa L.)”
e2“After the larval population declined, there was recovery growth and TNC yields reached levels up to 0.09 metric ton/ha higher than where weevils were controlled.”
Claim · model-written summary
The TNC crossover was associated with delayed development and longer accumulation.
- Taxon
- alfalfaMedicago sativae0
- Organ / stage
- morphological developmente1
- Outcome
- crossover from lower to higher TNC levelse1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa ( Medicago sativa L.)”
e1“The crossover from lower to higher TNC levels was associated with delayed morphological development and a prolonged TNC accumulation period where damage occurred.”
Claim · model-written summary
Cutting before peak larvae reduced TNC during regrowth.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- cut before the larval population reached a peake2
- Interactor
- alfalfa weevilHypera posticae1pest
- Outcome
- TNC levelse2
- Direction
- reducede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa ( Medicago sativa L.)”
e1“alfalfa weevil ( Hypera postica Gyllenhal)”
e2“When alfalfa was cut before the larval population reached a peak, TNC levels were reduced during the regrowth period.”
Claim · model-written summary
More than two larvae per stem reduced canopy height.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Larval populations higher than two/steme2
- Interactor
- alfalfa weevilHypera posticae1pest
- Outcome
- canopy heighte2
- Direction
- reducede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa ( Medicago sativa L.)”
e1“alfalfa weevil ( Hypera postica Gyllenhal)”
e2“Larval populations higher than two/stem reduced canopy height and leaf percentages during defoliation.”
Claim · model-written summary
More than two larvae per stem reduced leaf percentages.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Larval populations higher than two/steme2
- Interactor
- alfalfa weevilHypera posticae1pest
- Outcome
- leaf percentagese2
- Direction
- reducede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa ( Medicago sativa L.)”
e1“alfalfa weevil ( Hypera postica Gyllenhal)”
e2“Larval populations higher than two/stem reduced canopy height and leaf percentages during defoliation.”
Claim · model-written summary
Moderately damaged plants increased leaf percentage during recovery.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- moderately damaged plantse2
- Interactor
- alfalfa weevilHypera posticae1pest
- Outcome
- leaf percentagee2
- Direction
- increasede2
- Comparator
- lightly defoliated plantse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa ( Medicago sativa L.)”
e1“alfalfa weevil ( Hypera postica Gyllenhal)”
e2“During the post‐defoliation recovery period, moderately damaged plants increased in leaf percentage and produced more branches than lightly defoliated plants.”
Claim · model-written summary
Moderately damaged plants produced more branches than lightly defoliated plants.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- moderately damaged plantse2
- Interactor
- alfalfa weevilHypera posticae1pest
- Outcome
- branchese2
- Direction
- moree2
- Comparator
- lightly defoliated plantse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa ( Medicago sativa L.)”
e1“alfalfa weevil ( Hypera postica Gyllenhal)”
e2“moderately damaged plants increased in leaf percentage and produced more branches than lightly defoliated plants.”
Claim · model-written summary
Moderately damaged plants remained shorter.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- moderately defoliated plantse2
- Interactor
- alfalfa weevilHypera posticae1pest
- Outcome
- shortere2
- Direction
- shortere2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alfalfa ( Medicago sativa L.)”
e1“alfalfa weevil ( Hypera postica Gyllenhal)”
e2“the moderately defoliated plants remained shorter”
The same questions in other papers
pruning · Hypera postica · Medicago sativa (alfalfa)Positive and negative results
4 in the opposite direction
- positive
- positive
- positive
1 paper more in this group
See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.