|
1
| 2 | 3 | 4
| 5 | 6 | 7
| 8 | 9 | 10
| 11 | 12 |
13 | 14 | 15
| 16 | 17 |
18 | 19 | 20
| 21 | 22
A New Look At
An Old Pest: What Makes Lygus Hungry For Cotton Squares?
| 10
Andrew G. Zink and Jay A. Rosenheim
Department of Entomology, University of California at
Davis
Growers have repeatedly stressed an enigma
that is familiar to cotton entomologists: sometimes there
are lots of Lygus in the field, but little or no crop damage,
whereas at other times even a few Lygus appear to generate
heavy crop damage. Past work has shown that Lygus nymphs
may inflict damage to squares that is equal to (or greater)
than that of adults.
However Lygus nymphs are very hard to sample
and may be "invisible" from a management perspective.
It is possible that the patterns of square loss in cotton
fields that appear enigmatic can be explained by more detailed
analyses of nymph densities and the age structure of Lygus
populations. We have found a broad range of age structure
in Lygus populations where nymphs ranged from 18% to 71%
of all individuals. This suggests that adult density alone
cannot accurately reflect (or predict) Lygus presence in
a particular field. We have also found that sweep nets are
less successful at capturing nymphs relative to adults,
which means that nymphs are often underestimated in populations.
At the next BASIC meeting we will talk in more detail about
these results and the implications for damage to cotton
squares and square retention.
back
to top
next article
|
