I dont know how to add comment to the sanet newsgroup, but here
goes. Larry Phelan at Ohio State has researched the effect of soil
management on insect feeding preference of European corn borer - see below.
AU: Phelan,-P.L.; Norris,-K.H.; Mason,-J.F.
TI: Soil-management history and host preference by Ostrinia nubilalis:
evidence for plant mineral balance mediating insect-plant interactions.
SO: Environ-entomol. Lanham, Md. : Entomological Society of America. Dec
1996. v. 25 (6) p. 1329-1336.
CN: DNAL QL461.E532
DE: ostrinia-nubilalis. zea-mays. oviposition-. organic-soils.
soil-fertility. soil-management. ammonium-nitrate. cattle-manure.
composts-. leaves-. mineral-content. protein-content. nutrient-balance.
photosynthesis-. growth-. dry-matter-accumulation. stomata-.
leaf-conductance. hosts-of-plant-pests. pest-resistance. models-.
AB: Organic-farming practitioners have long suggested that maximizing soil
biotic activity results in crops of reduced susceptibility to pests. In the
current study, we examined the ovipositional preference of Ostrinia
nubilalis (Hubner), the European corn borer, on sweet corn grown in the
greenhouse using soils from neighboring organic and conventional farms and
fertilized with NH4NO3, cow-manure compost, or left unamended. In addition
to ovipositional preference, we compared photosynthetic potential,
leaf-mineral profiles, and biochemical profiles measured by near-infrared
(NIR) spectroscopy. Significant variation in O. nubilalis oviposition among
fertilizer treatments was measured for plants in conventional soil, but not
for those in organic soil. Photosynthetic parameters, notably net
photosynthesis and stomatal conductance, correlated strongly with plant
biomass accumulation, but no correlations with O. nubilalis preference were
detected. In contrast, a quadratic model of 3 leaf-mineral levels (Zn, Al,
and N) showed a strong relationship with O. nubilalis oviposition (adjusted
r2 = 0.71); plant growth was best described by a quadratic model of N alone
(adjusted r2 = 0.69). The greatest differences in NIR spectra were caused
by protein, and soil-fertilizer combinations producing the lowest protein
levels were those whose plants received the greatest number of O. nubilalis
eggs. We suggest that differences in corn acceptability to O. nubilalis is
at least in part mediated by plant mineral balance, which incorporates both
absolute levels and ratios of minerals, and that an optimal balance of
these minerals is more likely to occur in organically managed soil because
of an inherent.
property of reducing variation in mineral availability in those soils.
Dept. Soil Science
Univ. of WI-Madison
1525 Observatory Dr.
Madison, WI 53706
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