J. Econ. Entomol.91 (1): 7-20 (1998) ABSTRACT The relationship between Irish potato tuber yield, So/anum tuberosum L., and defoliation by the Colorado potato beetle, Leptinotarsa decem/ineata (Say), was investigated and the use of regression and mean separation analyses as a basis for developing economic injury levels were compared. The type of statistical analysis used to describe this relatio...

Cotton (Gossypium hirsutum L.) leaf defoliation has a significant ecological and economical impact on cotton production. Thus the utilization of a natural leaf defoliation trait, which exists in wild diploid cotton species, in the development of tetraploid cultivated cotton will not only be cost effective, but will also facilitate production of very high-grade fiber. The primary goal of our res...

Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may ...

BACKGROUND Herbivore grazing is a multiple-component process that includes wounding, defoliation, and saliva deposition. Despite the extensive published research on mechanical wounding and defoliation, no analysis to identify the genes that specify defoliation and mechanical wounding has been performed. Moreover, the influence of the expression of these genes on plant regrowth after defoliation...

Previous studies have indicated that an increased asparagine to glutamine ratio (Asn : Gln) occurs in the xylem fluid of Lolium perenne 24 h after defoliation. However, the absolute changes in Asn and Gln leading to the increased Asn : Gln ratio are unknown. The present study tested the hypotheses that: (1) defoliation-induced changes in xylem amino acid composition occur in L perenne within th...

The impact of different levels of whole plant partial defoliation (WPPD) on the photosynthesis andprimarymetabolismofwheat,TriticumaestivumL.,was evaluatedat thevegetative and reproductive (grain-Þlling) developmental stages. Photosynthetic parameters such as photosynthesis, stomatal conductance, and transpiration, chlorophyll a ßuorescence, and plant morphological parameters, such asmain stemh...

Registered, multi temporal Landsat data of a study area in central Pennsylvania were analyzed to detect and assess changes in the forest canopy resulting from insect defoliation. Images taken July 19, 1976, and JUne 27, 1977, were chosen specifically to represent forest canopy conditions before and after defoliation, respectively. Several image manipulation and data transformation techniques, d...

To understand the responses to external disturbance such as defoliation and possible feedback mechanisms at global change in terrestrial ecosystems, it is necessary to examine the extent and nature of effects on aboveground-belowground interactions. We studied a temperate heathland system subjected to experimental climate and atmospheric factors based on prognoses for year 2075 and further expo...

Th e infl uence of partial defoliation performed at diff erent grapevine growth stages on yield components, vegetative growth and fruit composition of ‘Istrian Malvasia’ (‘Malvazija istarska’) vines was investigated. During two consecutive seasons partial defoliation was performed manually at three grapevine growth stages; before bloom (BB), aft er bloom (AB), and at the beginning of bunch clos...

Drought impacts on forests, including widespread die-off, are likely to increase with future climate change, although the physiological responses of trees to lethal drought are poorly understood. In particular, in situ examinations of carbon starvation and its interactions with and effects on infestation and hydraulic vulnerability are largely lacking. In this study, we conducted a controlled, ...