Biology Reference
In-Depth Information
The male prairie mole cricket (
Gryllotalpa major
) of the tallgrass prairies of the
south-central United States builds a specialized acoustical burrow to attract females
using airborne signals. Hill and Shadley (
2001
) have observed that contemporary
seismic signals are produced in the soil from unknown mechanisms, which are
hypothesized to be a mechanism to spacing males away from each other
8.5 Soil Pests, Sound Detection, and Biodiversity
Assessment
Analysis of soil sonic ambience allows monitoring soil-dwelling insect pests and
also evaluating soil biodiversity. The first aspect has been extensively studied in
applied agroecology but the second remains a quite unexplored field.
Acoustic evaluation of soil pests requires specific recording techniques. Collec-
tion of soil information requires not only standard microphones, but also piezoelec-
tric microphones, geophones, and accelerometers to capture soilborne vibrations
(Mankin et al.
2011
).
For instance, the vibrations of soil insects considered agricultural pests, such as
Phyllophaga
white grubs and
Diaprepes
citrus rootweevils (
Diaprepes abbreviatus
L.)
(Coleoptera: Curculionidae), have been studied by Mankin et al. (
1998
) adopting a
portable accelerometer coupled to a microphone system.
To solve a practical problem such as that presented by a termite infestation in
trees and in houses, Mankin et al. (
2002
) proposed the use of an accelerometer
connected to an amplifier (Mankin et al.
1998
). These authors were able to
distinguish between background noise and three species of termites (
Reticulitermes
virginicus
,
Reticulitermes flavipes
, and
Coptotermes formosanus
), and they found a
correlation between the activity rate and the number of termites present.
The quality of soils is important in every ecosystem because soils are the home
for an important biodiversity. Soil health is coincident with the health of fungi,
plants, and animals. Monitoring soils represents an important practice to survey the
quality of the environment. The use of acoustic methodologies to survey the animal
content of a soil appears a very promising technique, encouraged by sophisticated
digital probes that can “listen” with great accuracy to the soil-borne sounds.
For instance, the mapping of soil invertebrates carried out by Brandhorst-
Hubbard et al. (
2001
) in hayfields of Alabama using electronic microphones has
demonstrated a good correlation between destructive traditional soil investigation
and acoustic analysis (Fig.
8.6
).
Summary
Soil is a medium rich in acoustic information. Most of the sounds present in the soil
are originated by stridulating animals or are the result of the digging activity of
fossorial organisms. Acoustic information from the soil is an important tool to
monitor soil biodiversity in a nondestructive way.
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