Michael C. Saunders

Modeling Development in Grape Berry Moth (Lepidoptera: Tortricidae)

Abstract We modeled development in grape berry moth, Endopiza viteana (Clemens), which exploits wild and cultivated Vitis. Laboratory experiments were used to derive the temperature-dependent developmental curve for eggs, larvae, and pupae. We used linear interpolation to estimate stage-specific base temperature thresholds and degree-day requirements under laboratory conditions. We also estimated parameters of the Logan and Lactin nonlinear developmental models. Lastly, we conducted field experiments to evaluate the conventional degree-day model, which has a base threshold of 10°C; an improved degree-day model that was based on our laboratory observations; and nonlinear developmental models in predicting seasonal grape berry moth development. We concluded that the Logan nonlinear model provided the best estimates of grape berry moth field development, and an improved degree-day model should use 8.41°C as a minimum base temperature threshold and 423.9 as the egg-to-adult degree-day requirement. Also, after comparing degree-day accumulation estimates using the maximum-minimum method and trapezoidal integration to hourly temperature measurements, we concluded that the two approaches provided similar estimates during June–September.

Toxic and Behavioral Effects to Carabidae of Seed Treatments Used on Cry3Bb1- and Cry1Ab/c-Protected Corn

Abstract Most transgenic corn seed is now treated with systemic neonicotinoid insecticides. To address potential direct nontarget effects of these combined technologies, 16 Carabidae species from 10 genera (Agonum, Amara, Anisodactylus, Bembidion, Chlaenius, Harpalus, Patrobus, Poecilus, Pterostichus, and Scarites) field-collected from corn were directly exposed to Bacillus thuringiensis (Bt) Cry toxin-laden pollens and seed treatments in feeding and defined-dose bioassays. All adults readily fed on field or sweet corn pollens that expressed coleopteran-specific Cry3Bb1 or lepidopteran-targeting Cry1Ab/c, and no significant toxicity was observed. Adult survivorship ranged from 47 d for the predator Pterostichus melanarius (Illiger) to a year for the more omnivorous Scarites quadriceps Chaudoir, feeding solely on pollen containing 30–90 μg Cry3Bb1/g and water. In contrast, commercial doses of neonicotinoid seed treatments (imidacloprid, thiamethoxam, or clothianidin) elicited nearly complete mortality for 18 carabid species in 4-d bioassays containing corn seedlings. Carabid consumption of fungicide-only (fludioxonil plus mefenoxam) seed treatments was generally observed within 1 d, compared with a 2-d latency on neonicotinoid treatments, suggesting an antifeedant effect of the insecticide. In microcosm bioassays containing a corn seedling and five prey, clothianidin seed treatments killed adult western corn rootworm, Diabrotica virgifera virgifera LeConte and S. quadriceps, although the smaller Harpalus pensylvanicus (DeGeer) was more tolerant. We conclude that the neonicotinoid/fungicide seed treatments, and not Cry3Bb1 or CryIAb/c, are a major direct mortality factor for ground beetles. Field studies are needed to determine population and community level effects on Carabidae when these transgenic and seed-treatment technologies are combined.

Phenology of Grape Berry Moth (Lepidoptera: Tortricidae) in Cultivated Grape at Selected Geographic Locations

Abstract The grape berry moth, Endopiza viteana (Clemens) feeds on wild and cultivated Vitis spp., causing economic damage in the latter. We studied incidence of pheromone trap catch data, and combined this with previous work on development and diapause to construct a comprehensive model of the temporal dynamics of E. viteana. We explored the behavior of this model in six eastern United States locations along Lakes Erie and Michigan, the Finger Lakes in New York, and in Missouri and Virginia. Voltinism of E. viteana is influenced by the accumulated growing degree-days before the postsummer solstice photoperiod at which eggs develop exclusively into diapausing pupae. Our model generally predicted two full and a partial third generation in Geneva, NY, whereas partial fourth generations existed in vineyards along Lakes Erie and Michigan. In more southern latitudes, such as Missouri and Virginia, the absence of a partial fourth generation would be rare. Also, our model suggested the presence of clinal latitudinal variation in diapause induction, with southern populations of E. viteana responding to shorter daylengths than northern populations. These predictions, based on average 10-yr surface temperatures (1991–2000), are supported by past observations and explain the variability in voltinism from year to year that has been reported in the northeastern United States and Niagara Peninsula of Canada.

Gut Microbes Contribute to Nitrogen Provisioning in a Wood-Feeding Cerambycid

ABSTRACT Xylophagous insects often thrive on nutritionally suboptimal diets through symbiotic associations with microbes that supplement their nutritional requirements, particularly nitrogen. The wood-feeding cerambycid Anoplophora glabripennis (Motschulsky) feeds on living, healthy host trees and harbors a diverse gut microbial community. We investigated gut microbial contributions to larval nitrogen requirements through nitrogen fixing and recycling (urea hydrolysis) processes, using a combination of molecular, biochemical, and stable isotope approaches. Genes and transcripts of conserved regions of the urease operon (ureC) and nitrogen fixing (nif) regulon (nifH) were detected in A. glabripennis eggs and larvae from naturally infested logs and from larvae reared on artificial diet. Significant nitrogen fixation and recycling were documented in larvae using 15N2 gas and 15N-urea, respectively. Subsequent 15N-routing of incorporated recycled nitrogen into larval essential and nonessential amino acids was shown for 15N-urea diet-fed larvae. Results from this study show significant gut microbial contributions to this insects metabolic nitrogen utilization through nitrogenous waste product recycling and nitrogen fixation.

Diapause Maintenance and Termination in Grape Berry Moth (Lepidoptera: Tortricidae)

Abstract We studied pupal diapause maintenance and termination in Endopiza viteana, a pest of commercially grown grapes. We observed considerable variation in diapause intensity, which ranged from 5.5 to 10 mo under natural temperatures and photoperiods. Adult males tended to emerge from diapause slightly earlier than females, suggesting that E. viteana may be protandrous. In the field, low temperatures maintained diapause in overwintering pupae, and adult emergence began at ≈148 degree-days accumulated from 1 January. Photoperiod did not influence diapause termination in E. viteana. Overall, most adults emerged in spring at roughly the same time, regardless of the date at which pupae entered diapause; however, emergence was extended over a 6-wk period. Moreover, eggs oviposited by late-emerging females may experience photoperiods that would lead to diapause in pupae. Under natural conditions, extended adult emergence may result in overlapping generations; accordingly, coordinating the timing of control tactics with peak oviposition is very difficult for this insect pest.

A knowledge-based approach for classifying lake water chemistry

Knowledge-based systems are computer models that facilitate reasoning such that human experience and expertise can be represented and made available to non-specialists. In this paper we describe the application of a knowledge-engineering methodology, using the NetWeaver™ software, to the problem of lakewater acid-base chemistry assessment. We present, and document with examples, the structure, arguments, and criteria values of a knowledge-based decision support system for classifying lakes in five acid-sensitive regions of the United States. We also discuss the significance of this software tool for federal land managers in the management of aquatic resources in national parks, national wildlife refuges, and wilderness areas to protect against water quality degradation associated with atmospheric deposition of sulfur and nitrogen. The Lake Chemistry knowledge bases have undergone repeated testing by members of a lake chemistry domain expert panel. There is agreement among the panel that these regional models provide accurate classifications of lakewater chemistries. The graphical and executable rendering of knowledge bases within NetWeaver™ greatly facilitates the knowledge engineering process, as it permits the inclusion of the domain expert(s) in the knowledge representation process and hence encourages greater participation in the design of the final knowledge-based model. In addition, the inclusion of fuzzy arguments, against which data values can be compared, greatly reduces the potential for combinatorial explosion that often occurs in expert systems that rely on categorical data interpretation, while at the same time providing a robust description of complex systems. It is our expectation that adoption of this approach, and others like it, will stimulate further development of knowledge-based systems for agriculture, natural resource management, and other complex decision support arenas.

Diapause induction in the grape berry moth (Lepidoptera : Tortricidae)

Abstract Photoperiod influences diapause induction in the grape berry moth, Endopiza viteana (=Polychrosis viteana), and eggs and neonates (<12 h) were the most sensitive to decreasing photoperiod. When held at photoperiods of 7–14 h, eggs produced mostly diapausing pupae, whereas at 15 h, development proceeded without diapause. Neonate larvae also showed sensitivity to short photoperiods, but responsiveness of larvae decreased rapidly with age, so that instars greater than 12 h old exposed to a short photoperiod of 8 h developed into adults without diapause. Eggs held at a high temperature (30°C) and 8-h photoperiod also produced diapausing pupae, suggesting that diapause induction in E. viteana is independent of temperature. Field studies showed considerable population variation in diapause induction, and an exponential saturation model predicted that 50 and 90% of individuals entered diapause at photoperiods of 14 h, 45.5 min and 14 h, 21.1 min, respectively.

Projecting Insect Voltinism Under High and Low Greenhouse Gas Emission Conditions

ABSTRACT We develop individual-based Monte Carlo methods to explore how climate change can alter insect voltinism under varying greenhouse gas emissions scenarios by using input distributions of diapause termination or spring emergence, development rate, and diapause initiation, linked to daily temperature and photoperiod. We show concurrence of these projections with a field dataset, and then explore changes in grape berry moth, Paralobesia viteana (Clemens), voltinism that may occur with climate projections developed from the average of three climate models using two different future emissions scenarios from the International Panel of Climate Change (IPCC). Based on historical climate data from 1960 to 2008, and projected downscaled climate data until 2099 under both high (A1fi) and low (B1) greenhouse gas emission scenarios, we used concepts of P. viteana biology to estimate distributions of individuals entering successive generations per year. Under the low emissions scenario, we observed an earlier emergence from diapause and a shift in mean voltinism from 2.8 to 3.1 generations per year, with a fraction of the population achieving a fourth generation. Under the high emissions scenario, up to 3.6 mean generations per year were projected by the end of this century, with a very small fraction of the population achieving a fifth generation. Changes in voltinism in this and other species in response to climate change likely will cause significant economic and ecological impacts, and the methods presented here can be readily adapted to other species for which the input distributions are reasonably approximated.

Application of a regionalized knowledge-based model for classifying the impacts of nitrogen, sulfur, and organic acids on lakewater chemistry

To maintain healthy ecosystems, it is increasingly imperative that federal land managers be prepared to monitor and assess levels of atmospheric pollutants and ecological effects in national parks, wildlife refuges, and wilderness areas. Atmospheric deposition of sulfur and/or nitrogen has the potential to damage sensitive terrestrial, and especially aquatic, ecosystems and can affect the survival of in-lake and in-stream biota. Federal land managers have a need to assess, at the individual park or wilderness area level, whether surface water resources are sensitive to air pollution degradation and the extent to which they have been impacted by atmospheric deposition of sulfur or nitrogen or influenced by other complicating factors. The latter can include geologic sources of sulfur, natural organic acidity, and the influence of disturbance and land use on water quality. This paper describes a knowledge-based decision support system (DSS) network for classifying lakewater resources in five acid-sensitive regions of the United States. The DSS allows federal land managers to conduct a preliminary assessment of the status of individual lakes prior to consulting an acid–base chemistry expert. The DSS accurately portrays the decision structure and assessment outcomes of domain experts while capturing interregional differences in acidification sensitivity and historic acid deposition loadings. It is internally consistent and robust with respect to missing water chemistry input data.

A Knowledge System Environment for Ecosystem Management

Ecosystem management is a collective term used to embrace a philosophy and set of methodologies associated with land-use manipulation or modification (Grumbine 1994; Kaufmann et al. 1995; Sedjo 1995; Lackey 1996). Broad-based issues dealt with under the umbrella of ecosystem management include biodiversity (Wilson 1992; Groombridge 1995; Heywood and Watson 1995), sustainability of ecological systems (Lubchenco et al. 1991; Risser et al. 1991; Covington and DeBano 1993; Levin 1993; Bormann et al. 1994a), maintenance of ecosystem health (Costanza et al. 1993; USDA Forest Service 1996), preservation of ecosystem integrity (Monnig and Byler 1992; Woodley et al. 1993). conservation and stewardship (Sample 1991; Callicott 1994; Alpert 1995), public participation (Wondolleck 1988; Knopp and Caldbeck 1990; Loikkanen 1995), and landscape management (Lucas 1991; Diaz and Apostol 1993; Urban 1993; Boyce 1995; Forman 1995a, 1995b).