ABSTRACT
There is considerable variation in the contents of the digestive tracts of trap-captured weevils. If the rate at which the digestive tract empties after
feeding were known, observation of gut condition might be useful in
estimating the time elapsed since a weevil last fed. Because this
information is currently unavailable, we examined the rate of food (cotton
pollen) passage through digestive tracts of boll weevils held at 12.8, 18.3, 23.9, and 29.4°C (55, 65, 75, and 85°F, respectively). At 29.4°C, intact
pollen grains were no longer visible in the midgut 12 h after last feeding.
At 23.9 and 18.3°C, pollen grains were no longer distinguishable in the
midgut after 48 h. At 12.8°C, intact pollen grains were no longer present
in the sacular portion of the midgut after 48 h, but remained visible in the
tubular section of some weevils for up to 12 d. The majority of weevils,
regardless of temperature, retained remnants of food in the hindgut. Our
study indicates that examination of food content in the tubular portion of
the weevil midgut is the best indicator for assessing the recent feeding
history of trap-captured weevils. Weevils containing solid food in this
portion of the gut can be presumed to have fed within the past 24 to 48 h.
This technique should prove useful in studies to infer the previous food
source of weevils captured in traps, and provide insight into their potential
origin.
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