Petersen M.J.,Cornell University |
Seto M.,Cornell University |
Peck D.,Cornell University |
Peck D.,Grass Systems Entomology LLC
Ecological Entomology | Year: 2013
The persistence of a species within a habitat patch is determined by the degree to which the habitat meets the species' biotic and abiotic requirements. Local-scale spatio-temporal population dynamics should be structured by the heterogeneity of these factors within the habitat patch. This study relates the abiotic (soil moisture) and biotic (plant community) factors defining a continuous turfgrass environment to the temporal population structure and spatial distribution of Tipula paludosa ontogenetic stages across 3years of investigation. Populations declined greatly from first instar to pupa across all sites. Survival was greatest in soils with higher water-holding capacity. Intra-patch insect spatial distributions were associated with soil moisture but not with plant community distributions. A sink-source dynamic was evident. Low quality habitats could have high first instar populations, but these did not survive until pupation. Where high and low quality habitats intersected, there was a tendency for high quality habitats to be sparsely populated. Tipula paludosa spatio-temporal distributions are dynamic throughout the life cycle. This work suggests that population persistence within a habitat patch is determined by the quality of the habitat, largely defined by soil moisture, and the juxtaposition of high and low quality habitats within the patch. © 2013 The Royal Entomological Society.
Petersen M.J.,Cornell University |
Peck D.C.,Cornell University |
Peck D.C.,Grass Systems Entomology LLC
Journal of Economic Entomology | Year: 2013
Feeding on above- and belowground plant tissues by Tipula paludosa Meigen during the period of rapid growth from second to forth instars is highly damaging to cool-season (C3) turfgrasses. It may be possible to reduce this damage by identifying grass genotypes that increase host plant protection. This study examined the impacts of plant genotype, endophyte infection, and plant ontogeny on host plant and insect responses during whole-plant feeding by T. paludosa. A series of no-choice greenhouse trials were conducted with third instar crane flies to determine 1) host plant tolerance in terms of reductions to above- and belowground plant biomass, 2) antixenosis resistance impacting insect behavior (emigration), and 3) antibiosis resistance impacting insect growth. Results showed that insect infestation level was the primary factor influencing plant biomass reductions. Belowground tissues were more tolerant to feeding than were aboveground tissues, with tall fescues, Festuca arundinacea Schreber, being most resistant to aboveground biomass reduction. Host plant associations with intercellular fungal endophytes (E+) decreased insect weight gain and decreased insect movement, but did not increase host plant tolerance. Plant ontogeny affected this response with insect weight gain significantly decreased on young (28 d) growth E+ grasses but not on old (90 d) growth E+ grasses, however. Host plant genotype and plant ontogeny can have significant impacts to host plant tolerance and insect physiology for T. paludosa larva. Furthermore, plant-endophyte associations have apparent sublethal effects that impact insect fitness and may further enhance host plant protection. © 2013 Entomological Society of America.