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Vertical movement of adult rusty grain beetles, Cryptolestes ferrugineus, in stored corn and wheat at uniform moisture content.

Jian F, Jayas DS, White ND - J. Insect Sci. (2006)

Bottom Line: Adults showed downward displacement over 24 h when corn moisture was lower than 15.5%, but they did not show downward displacement when moisture content was 17.5%.The upward or downward movement might partially be caused by a drift effect due to beetles sliding between seeds and the displacement of the adults might be the combined effect of walking and falling during their movement.Adults had a similar movement and distribution in both the small and large wheat columns.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada.

ABSTRACT
Vertical movement and distribution of Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) adults in stored wheat and corn were studied in small (0.1 x 0.1 x 1 m) and large (0.6 m diameter and 1.12 m high) columns. The adults were introduced at the top, middle, and bottom of the small columns with a uniform moisture content (wheat: 14.5 +/- 0.1%, corn 13.5 +/- 0.1%, 15.5 +/- 0.1%, and 17.5 +/- 0.1%) at 27.5 +/- 0.5 degrees C. When introduced at different locations, adults showed a similar distribution in stored grain bulk with a uniform temperature and moisture content of 14.5% for wheat or 15.5% for corn. Adults showed downward displacement over 24 h when corn moisture was lower than 15.5%, but they did not show downward displacement when moisture content was 17.5%. The upward or downward movement might partially be caused by a drift effect due to beetles sliding between seeds and the displacement of the adults might be the combined effect of walking and falling during their movement. The hydrophilic behavior plus the drift effect explain why the beetles had a faster downward dispersal in the 13.5% corn than in the 15.5% and 17.5% corn and a slight upward displacement in 17.5% corn because they were more active at the lower moisture contents. Adults had a similar movement and distribution in both the small and large wheat columns.

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Vertical distribution of the Cryptolestes ferrugineus adults in columns of corn at 27.5 ± 0.2°C (n = 3). The moisture content of the corn was varied: a = 13.5 ± 0.2%; b = 15.5 ± 0.2%; c =17.5 ± 0.2%. 100 adults were initially introduced at the middle of the columns and movement was measured in 1, 3, or 24 h. The same data were used in Fig.4b (the 24 h data) as in Fig. 3a (data for those introduced in the middle of the column).
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i1536-2442-6-11-1-f04: Vertical distribution of the Cryptolestes ferrugineus adults in columns of corn at 27.5 ± 0.2°C (n = 3). The moisture content of the corn was varied: a = 13.5 ± 0.2%; b = 15.5 ± 0.2%; c =17.5 ± 0.2%. 100 adults were initially introduced at the middle of the columns and movement was measured in 1, 3, or 24 h. The same data were used in Fig.4b (the 24 h data) as in Fig. 3a (data for those introduced in the middle of the column).

Mentions: Beetles introduced in the middle of the small corn columns showed a downward dispersal except at a moisture content of 17.5% after a 24 h movement period (Fig. 4a, b, and c). The percent moving, the PA value, decreased with increasing moisture content (Table 3). At moisture contents of 13.5% and 15.5%, the PA value increased with longer movement time and all of the PA values were > 0, while the values decreased with longer movement times at a moisture content of 17.5% and PA values were > 0 when the movement time was at 1 or 3 h (Table 3). These results showed that beetle movement was different at different moisture content, and downward dispersal might relate to the hydrophilic behavior of the adults when the grain was dry. When grain is drier, they might more actively look for positions with biologically suitable moisture contents. In many granaries, downward dispersal would bring beetles near the floor where higher moisture often accumulates from rain or snow that enters the granary (Loschiavo, 1983). The hydrophilic behavior and greater activity in dryer grain plus the sliding downward effect explain why the beetles had a faster downward dispersal in the 13.5% corn than in the 15.5% and 17.5% moisture content corn. The 17.5% moisture content is slightly higher than the preferred moisture content of C. ferrugineus (Sinha and Watters 1985). This could explain why in the corn column with 15.5 and 17.5% moisture contents most of beetles stayed in the introduction position after 1 and 3 hours (Fig. 4b,c). By 24 hours more had moved up or down from the introduction position. Interestingly, the beetles showed a negative geotactic behavior after 24 hours when corn moisture was at 17.5% (Fig. 4c). Apparently, if beetles were allowed more time in the dryer grain column (Fig. 4a,b), the driving force to look for a wetter position, which is usually lower in a grain bin, could result in more adults moving down. This inference is consistent with the reports of Jian et al. (2005b).


Vertical movement of adult rusty grain beetles, Cryptolestes ferrugineus, in stored corn and wheat at uniform moisture content.

Jian F, Jayas DS, White ND - J. Insect Sci. (2006)

Vertical distribution of the Cryptolestes ferrugineus adults in columns of corn at 27.5 ± 0.2°C (n = 3). The moisture content of the corn was varied: a = 13.5 ± 0.2%; b = 15.5 ± 0.2%; c =17.5 ± 0.2%. 100 adults were initially introduced at the middle of the columns and movement was measured in 1, 3, or 24 h. The same data were used in Fig.4b (the 24 h data) as in Fig. 3a (data for those introduced in the middle of the column).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2990299&req=5

i1536-2442-6-11-1-f04: Vertical distribution of the Cryptolestes ferrugineus adults in columns of corn at 27.5 ± 0.2°C (n = 3). The moisture content of the corn was varied: a = 13.5 ± 0.2%; b = 15.5 ± 0.2%; c =17.5 ± 0.2%. 100 adults were initially introduced at the middle of the columns and movement was measured in 1, 3, or 24 h. The same data were used in Fig.4b (the 24 h data) as in Fig. 3a (data for those introduced in the middle of the column).
Mentions: Beetles introduced in the middle of the small corn columns showed a downward dispersal except at a moisture content of 17.5% after a 24 h movement period (Fig. 4a, b, and c). The percent moving, the PA value, decreased with increasing moisture content (Table 3). At moisture contents of 13.5% and 15.5%, the PA value increased with longer movement time and all of the PA values were > 0, while the values decreased with longer movement times at a moisture content of 17.5% and PA values were > 0 when the movement time was at 1 or 3 h (Table 3). These results showed that beetle movement was different at different moisture content, and downward dispersal might relate to the hydrophilic behavior of the adults when the grain was dry. When grain is drier, they might more actively look for positions with biologically suitable moisture contents. In many granaries, downward dispersal would bring beetles near the floor where higher moisture often accumulates from rain or snow that enters the granary (Loschiavo, 1983). The hydrophilic behavior and greater activity in dryer grain plus the sliding downward effect explain why the beetles had a faster downward dispersal in the 13.5% corn than in the 15.5% and 17.5% moisture content corn. The 17.5% moisture content is slightly higher than the preferred moisture content of C. ferrugineus (Sinha and Watters 1985). This could explain why in the corn column with 15.5 and 17.5% moisture contents most of beetles stayed in the introduction position after 1 and 3 hours (Fig. 4b,c). By 24 hours more had moved up or down from the introduction position. Interestingly, the beetles showed a negative geotactic behavior after 24 hours when corn moisture was at 17.5% (Fig. 4c). Apparently, if beetles were allowed more time in the dryer grain column (Fig. 4a,b), the driving force to look for a wetter position, which is usually lower in a grain bin, could result in more adults moving down. This inference is consistent with the reports of Jian et al. (2005b).

Bottom Line: Adults showed downward displacement over 24 h when corn moisture was lower than 15.5%, but they did not show downward displacement when moisture content was 17.5%.The upward or downward movement might partially be caused by a drift effect due to beetles sliding between seeds and the displacement of the adults might be the combined effect of walking and falling during their movement.Adults had a similar movement and distribution in both the small and large wheat columns.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada.

ABSTRACT
Vertical movement and distribution of Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) adults in stored wheat and corn were studied in small (0.1 x 0.1 x 1 m) and large (0.6 m diameter and 1.12 m high) columns. The adults were introduced at the top, middle, and bottom of the small columns with a uniform moisture content (wheat: 14.5 +/- 0.1%, corn 13.5 +/- 0.1%, 15.5 +/- 0.1%, and 17.5 +/- 0.1%) at 27.5 +/- 0.5 degrees C. When introduced at different locations, adults showed a similar distribution in stored grain bulk with a uniform temperature and moisture content of 14.5% for wheat or 15.5% for corn. Adults showed downward displacement over 24 h when corn moisture was lower than 15.5%, but they did not show downward displacement when moisture content was 17.5%. The upward or downward movement might partially be caused by a drift effect due to beetles sliding between seeds and the displacement of the adults might be the combined effect of walking and falling during their movement. The hydrophilic behavior plus the drift effect explain why the beetles had a faster downward dispersal in the 13.5% corn than in the 15.5% and 17.5% corn and a slight upward displacement in 17.5% corn because they were more active at the lower moisture contents. Adults had a similar movement and distribution in both the small and large wheat columns.

Show MeSH
Related in: MedlinePlus