Insect pathogenicity in plant-beneficial pseudomonads: phylogenetic distribution and comparative genomics.

Bacteria of the genus Pseudomonas occupy diverse environments. The Pseudomonas fluorescens group is particularly well-known for its plant-beneficial properties including pathogen suppression. Recent observations that some strains of this group also cause lethal infections in insect larvae, however, point to a more versatile ecology of these bacteria. We show that 26 P. fluorescens group strains, isolated from three continents and covering three phylogenetically distinct sub-clades, exhibited different activities toward lepidopteran larvae, ranging from lethal to avirulent. All strains of sub-clade 1, which includes Pseudomonas chlororaphis and Pseudomonas protegens, were highly insecticidal regardless of their origin (animals, plants). Comparative genomics revealed that strains in this sub-clade possess specific traits allowing a switch between plant- and insect-associated lifestyles. We identified 90 genes unique to all highly insecticidal strains (sub-clade 1) and 117 genes common to all strains of sub-clade 1 and present in some moderately insecticidal strains of sub-clade 3. Mutational analysis of selected genes revealed the importance of chitinase C and phospholipase C in insect pathogenicity. The study provides insight into the genetic basis and phylogenetic distribution of traits defining insecticidal activity in plant-beneficial pseudomonads. Strains with potent dual activity against plant pathogens and herbivorous insects have great potential for use in integrated pest management for crops

What Determines Student Evaluation Scores? A Random Effects Analysis of Undergraduate Economics Classes

Student evaluation scores are a standard component of the way colleges and universities assess the quality of an instructor's teaching for purposes of promotion and tenure, as well as merit raise allocations. This paper applies a feasible generalized least squares model to a panel of data from undergraduate economics classes. We find that instructors can “buy” better evaluation scores by inflating students’ grade expectations. Class size and instructor experience are important determinants of evaluation scores in principles classes, but not in upper-level courses. Male instructors get better scores than females, and younger instructors are more popular than older ones. Certain other factors are also important determinants of evaluation scores. Our results suggest that an adjustment to the usual departmental rankings may be useful. Eastern Economic Journal (2009) 35, 37–51. doi:10.1057/palgrave.eej.9050042