CORN AND SOYBEAN CROP INFLUENCE
The influence of tarnished plant bug on corn and soybean populations in
General description of research:
Corn may play an important role in the dynamics of tarnished plant bug
populations that infest mid- late-season cotton. Prior to research conducted
at the USDA-ARS Southern Insect Management Research Unit (SIMRU), consultants
and researchers had collected nymphs and adult stage tarnished plant bugs
from corn; however, it was unknown if the insect was able to reproduce
on the crop.
Our objectives at SIMRU are to:
Determine if the pest can develop on corn tissue
Quantify egg production for plant bug adults reared on corn tissue
Determine the location and timing of plant bug oviposition on corn
Study the life history of plant bug development on corn
Quantify the population densities of plant bugs developing on corn that
could potentially move into mid- to late-season cotton
Determine the association between corn earworm damage to the corn ear
and tarnished plant bug development on developing corn seed.
The ultimate goal of this research is to determine if plant bugs reproduce
in corn at sufficient levels to warrant control of the pest before it infests
mid- to late-season cotton.
In the laboratory, we have discovered that tarnished plant bugs can develop
successfully on pollen-shedding corn tassels (75.0% developed to adults)
and blister- and milk-stage kernels collected from corn ears. Development
on these tissues was not different when compared to the broccoli control.
When adult female fecundity was checked, the female tarnished plant bugs
that were reared on broccoli produced significantly more eggs than those
females reared on milk-stage kernels, but not those reared on corn cob
tips which contained blister- and milk-stage kernels. Because developing
corn seed from healthy ears is unavailable to plant bug feeding, ear damage
by the corn earworm/bollworm may be important for the tarnished plant bug
to feed and complete its normal development.
In the field, we found tarnished plant bug eggs oviposited on the leaf
sheath, leaf mid-rib, tassels, and silks of corn (Photos 1-3). We examined
whole corn plants for tarnished plant bugs throughout the corn growing
season and discovered the greatest number of plant bugs on R2 (milk stage)
corn. During this stage, we recorded an average of 6.2% tarnished plant
bugs/plant. The highest number of plant bugs infesting corn (12.7% of plants)
occurred on 20 June, 2003 on R2 stage corn that was planted 18 April, 2003.
For irrigated corn grown in the MS Delta, normal plant populations for
corn are at 40,000 plants/acre. If we assume 6.2% of these plants will
produce one tarnished plant bug, 2,480 tarnished plant bugs may be produced
per acre of field corn. Additional research will be needed to determine
if this level of reproduction in corn is occurring and if it is economically
significant for cotton producers.
Notice how the eggs below were not inserted into the tissue, but were
laid on top. These eggs may not hatch properly.
Photo 1. Eggs laid in corn sheath.
Photo 2. Egg laid in corn silk.
Photo 3. Eggs laid on corn tassel.
Large scale strip-plots of cotton planted next to corn, cotton or soybean
will be either sprayed unsprayed with insecticide to determine the relative
differences in plant bug densities emerging and infesting mid- to late-season
The development of tarnished plant bug on soybean will be investigated
in 2004 and 2005. A study to determine the life history of the pest on
soybean will also be conducted during these two years.
For more information contact:
PO Box 346
141 Experiment Station Rd
Stoneville, MS 38776
Abel, C. A. and G. L. Snodgrass. 2003. The development of tarnished plant
bug on various corn tissue. In Proc. Cotton Res. Conf. Natl. Cotton Council
Amer. Nashville TN, www.cotton.org/beltwide