@article{costa_kennedy_heagle_2001, title={Effect of host plant ozone stress on Colorado potato beetles}, volume={30}, ISSN={["1938-2936"]}, DOI={10.1603/0046-225X-30.5.824}, abstractNote={Abstract Effects of ozone (O3) stress of potato, Solanum tuberosum L., on fecundity, larval growth and survival of Colorado potato beetles, Leptinotarsa decemlineata (Say), were measured in greenhouse and field experiments. Chronic O3 exposure caused moderate to severe foliar injury on an O3-sensitive cultivar (‘Red Norland’) but caused only minor injury an O3-resistant cultivar (‘Superior’). Foliar injury caused by O3 was greater on old than on young leaves but feeding by adult beetles was greater on young leaves in all experiments. Foliar analyses of the five uppermost leaves (nodes 1–5) showed higher carbon (C) and higher nitrogen (N) concentration in Superior than in Norland. There were no significant O3 effects on C or N and no cultivar × O3 interactions. Egg production by newly emerged adult beetles feeding on plants exposed to high O3 levels was not significantly different from egg production on plants exposed to low O3 levels, regardless of cultivar O3 sensitivity. Feeding and energy conversion efficiency of neonates and survival of larvae to the adult stage were not significantly affected by the O3 treatment. Although present levels of tropospheric O3 are high enough to significantly affect yield of sensitive potato cultivars, our results indicate no significant effect of ambient O3 concentrations on Colorado potato beetle populations.}, number={5}, journal={ENVIRONMENTAL ENTOMOLOGY}, author={Costa, SD and Kennedy, GG and Heagle, AS}, year={2001}, month={Oct}, pages={824–831} }
 @article{costa_barbercheck_kennedy_2001, title={Mortality of Colorado potato beetle (Leptinotarsa decemlineata) after sublethal stress with the CryIIIA delta-endotoxin of Bacillus thuringiensis and subsequent exposure to Beauveria bassiana}, volume={77}, ISSN={["1096-0805"]}, DOI={10.1006/jipa.2001.5017}, abstractNote={Acute or chronic sublethal exposure of Colorado potato beetle larvae to the CryIIIA delta-endotoxin of Bacillus thuringiensis Berliner did not significantly (P > 0.05) alter their subsequent susceptibility to Beauveria bassiana (Balsamo) Vuillemin. During the period of exposure to B. bassiana there was continued mortality from previous exposure to delta-endotoxin, and B. bassiana also caused significant mortality. Acute and chronic exposure to delta-endotoxin significantly prolonged larval development. The weights of prepupae and adults were significantly reduced by exposure to delta-endotoxin, with the greatest effect being from chronic exposure. Separation of the manifestations of stress in time (feeding vs soil stages) and space (toxin damage to the insect gut vs fungal penetration of the cuticle and activity in the hemocoel) may have precluded alteration of insect susceptibility to infection by B. bassiana. Endemic populations of B. bassiana are not expected to influence the development of resistance in the Colorado potato beetle to the delta-endotoxin of B. thuringiensis.}, number={3}, journal={JOURNAL OF INVERTEBRATE PATHOLOGY}, author={Costa, SD and Barbercheck, ME and Kennedy, GG}, year={2001}, month={Apr}, pages={173–179} }
 @article{nault_costa_kennedy_2000, title={Colorado potato beetle (Coleoptera : Chrysomelidae) feeding, development, and survival to adulthood after continuous exposure to Bacillus thuringiensis subsp tenebrionis-treated potato foliage from the field}, volume={93}, ISSN={["0022-0493"]}, DOI={10.1603/0022-0493-93.1.149}, abstractNote={Abstract Colorado potato beetle, Leptinotarsa decemlineata (Say), feeding, development, and survival to adulthood were examined after continuously exposing large larvae to Bacillus thuringiensis subsp. tenebrionis-treated potato foliage from the field. In laboratory assays, the overall consumption and the length of period to become prepupae were determined for larvae, which began as 3rd and 4th instars, that were offered potato leaf disks with naturally declining levels of B. thuringiensis residue. In small-cage field experiments, survival to adulthood and the period to adult emergence for beetles confined to potato plants treated with B. thuringiensis beginning as 3rd and 4th instars also were examined. Third instars remaining on plants after a B. thuringiensis application were unlikely to feed and 4th instars consumed only ≈50% as much foliage as those fed untreated foliage. Many late instars subjected to B. thuringiensis-treated foliage failed to survive to adulthood; 58–83% of these beetles died during the larval stage. Reduced feeding and poor survival of late instars suggest that counts of large larvae after application do not provide a complete picture of the efficacy of the B. thuringiensis treatment. Late instar Colorado potato beetles that were exposed continually to naturally declining levels of B. thuringiensis-treated potato foliage took an average of 1.8–4.5 d longer to become prepupae and 4–8 d longer to emerge as adults compared with those provided with untreated foliage. Delayed emergence of adults that fed on B. thuringiensis-treated potatoes as late instars indicated that development was prolonged in these insects because of ingestion of a sublethal dose of B. thuringiensis.}, number={1}, journal={JOURNAL OF ECONOMIC ENTOMOLOGY}, author={Nault, BA and Costa, SD and Kennedy, GG}, year={2000}, month={Feb}, pages={149–156} }
 @article{costa_barbercheck_kennedy_2000, title={Sublethal acute and chronic exposure of Colorado potato beetle (Coleoptera : Chrysomelidae) to the delta-endotoxin of Bacillus thuringiensis}, volume={93}, ISSN={["0022-0493"]}, DOI={10.1603/0022-0493-93.3.680}, abstractNote={Abstract Sublethal exposure of Colorado potato beetle, Leptinotarsa decemlineata (Say), larvae to the δ-endotoxin of Bacillus thuringiensis variety tenebrionis (Berliner) caused a dose-dependent reduction in feeding and weight gain when tested in a leaf disk bioassay. The highest doses of chronic (continuous-lower concentration) exposure resulted in peak foliage consumption on day 1 as compared with peak consumption on days 3 and 4 when exposure was acute (24-h higher concentration). Dose and exposure regimen interacted significantly in their effects on the extension of development. When development time was analyzed separately for each exposure regimen, only acute exposure caused significant delays in development that extended through to adult eclosion. The efficiency of conversion of ingested material to biomass (ECI) declined significantly with both exposure regimens. The lethal and most sublethal effects of exposure to δ-endotoxin were not cumulative, in that similar total doses, whether delivered acutely or chronically, produced different effects. Female adults that survived acute and chronic exposure to δ-endotoxin as larvae had significantly reduced weight and longevity, and tended to produce fewer eggs (45 and 44% reductions in acute and chronic exposures, respectively) when compared with control adults. The intrinsic rate of increase (r) and net reproductive rate (R0) also appeared to be reduced.}, number={3}, journal={JOURNAL OF ECONOMIC ENTOMOLOGY}, author={Costa, SD and Barbercheck, ME and Kennedy, GG}, year={2000}, month={Jun}, pages={680–689} }