Je. Slosser et al., SURVIVAL OF DIAPAUSING AND NONDIAPAUSING BOLL-WEEVILS (COLEOPTERA, CURCULIONIDAE) SUBJECTED TO FREEZING TEMPERATURES, Environmental entomology, 25(2), 1996, pp. 407-415
Boil weevils, Anthonomus grandis grandis Boheman, were subjected to fr
eezing temperatures of 0.0, -2.5, -5.0, -7.5, and -10.0 degrees C in a
cold bath. Survival of diapausing and nondiapausing adults was compar
ed after exposures of 2-, 4-, 6-, and 8-h duration. Diapausing and non
diapausing individuals could be separated by exposure to -7.5 degrees
C for 6 h; diapausing adults were alive and able to walk after this tr
eatment, whereas nondiapausing adults were dead or unable to stand. In
the diapausing group, young boil weevils (36 d old) were more toleran
t of freezing conditions than were older (110 d old) boil weevils. In
a 2nd test, diapausing adults were exposed to these 5 temperatures for
8-72 h. Roll weevils did not survive exposures greater than or equal
to 40 h duration at -10.0 degrees C. In a 3rd test, diapausing boil we
evils were subjected to temperatures of 0.0, -2.5, -5.0, and -7.5 degr
ees C for 4, 8, 16, and 24 h/d for 2, 6, 10, 14, and 18 consecutive da
ys. At the end of the daily freezing exposure, adults were removed fro
m the cold bath and held at 4.4 degrees C. No boll weevils survived th
e treatment combinations of -5.0 degrees C for 24 h/d for 14 d and of
-7.5 degrees C for 16 and 24 h/d for 10, 14, or 18 d. However, tempera
tures this low for this length of time are not common in the Texas Rol
ling Plains. In the regression equation relating survival with the var
ious exposure conditions, the linear and quadratic components for temp
erature were primary variables affecting survival in each of the 3 tes
ts.