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Comparative Study
. 2000 Mar 14;97(6):2637-40.
doi: 10.1073/pnas.050461497.

Learning improves growth rate in grasshoppers

R Dukas  1 , E A Bernays
Affiliations
Comparative Study

Learning improves growth rate in grasshoppers

R Dukas et al. Proc Natl Acad Sci U S A. .

Abstract

To quantify the adaptive significance of insect learning, we documented the behavior and growth rate of grasshoppers (Schistocerca americana) in an environment containing two artificial food types, one providing a balanced diet of protein and carbohydrate, which maximizes growth, and the other being carbohydrate-deficient, which is unsuitable for growth. Grasshoppers in the Learning treatment experienced a predictable environment, where the spatial location, taste, and color of each food source remained constant throughout the experiment. In contrast, grasshoppers of the Random treatment developed in a temporally varying environment, where the spatial location, taste, and color of the balanced and deficient food types randomly alternated twice each day. Our results show that the grasshoppers that could employ associative learning for diet choice experienced higher growth rates than individuals of the Random treatment, demonstrating the adaptive significance of learning in a small short-lived insect.

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Figures

Figure 1
Figure 1
A cage contained a water dish (w) and two food dishes, one consisting of a nutritionally balanced (B) and the other deficient (D) food. Twice a day, we removed the food dishes and introduced new dishes. The Learning grasshoppers experienced a predictable environment: the two food types were always placed at the same sides, near the same colored card, and with the same flavor. The Random grasshoppers had a temporally varying environment: the location, background color, and flavor of each diet type was randomly determined on each food change. The figure depicts two examples to illustrate the protocol; see Methods for full details.
Figure 2
Figure 2
The proportion (mean + SE) of visits to (a) and time spent feeding on (b) the dish containing nutritionally balanced food during the first 6 days of feeding. In addition, “F” on the abscissa refers to choice of the first observed meal (in a) or duration of the first meal on each diet type (in b).
Figure 3
Figure 3
The average growth rate (adjusted least-square means + SE) of grasshoppers from the Learning and Random treatments.
Figure 4
Figure 4
The time delay (mean + SE) between a first feeding attempt and the start of feeding on the balanced food dish during the first 6 days of feeding.
See this image and copyright information in PMC

References

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