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Protectants applied to grain can reduce damage caused by insect feeding during storage. Although these protectants are effective against many external feeders, they may also reduce damage caused by internal feeders as they often interact with the exterior surface of the grain during their larval or adult stages to feed or oviposit. For this study, we investigated impacts of Storicide® II applied to brown rice on three different internal feeders: Rhyzopertha dominica (Fauvel), Sitophilus oryzae (L.), and Sitotroga cerealella (Olivier). We also investigated the effects of this protectant at three different temperatures and when it was combined with different percentages of untreated brown rice. Time-series clustering was also performed to determine whether treatments caused disruptions to the timing of progeny emergence. Overall, R. dominica was the most susceptible as mortality and knockdown were observed in mixtures containing 10% treated brown rice. In contrast, S. cerealella was the least susceptible as mixtures containing at least 50–75% treated brown rice were required to reduce progeny production. However, lowering the temperature to 22 °C did reduce the amount of treated brown rice required to reduce progeny emergence and also reduced the number of progeny that emerged synchronously, which would likely reduce mating and reduce population levels over time. Similar effects on progeny were observed for S. oryzae and R. dominica. Overall, these findings suggest that Storicide II can reduce population levels of internal feeders and that combining this protectant with cooler temperatures can provide additional protection.
Erin D. Scully; Alison R. Gerken; Adriane Fifield; Valerie Nguyen; Nicholas Van Pelt; Frank H. Arthur. Impacts of Storicide II on internal feeders of Brown rice. Journal of Stored Products Research 2020, 90, 101758 .
AMA StyleErin D. Scully, Alison R. Gerken, Adriane Fifield, Valerie Nguyen, Nicholas Van Pelt, Frank H. Arthur. Impacts of Storicide II on internal feeders of Brown rice. Journal of Stored Products Research. 2020; 90 ():101758.
Chicago/Turabian StyleErin D. Scully; Alison R. Gerken; Adriane Fifield; Valerie Nguyen; Nicholas Van Pelt; Frank H. Arthur. 2020. "Impacts of Storicide II on internal feeders of Brown rice." Journal of Stored Products Research 90, no. : 101758.
The commercial availability of low-gluten or gluten-free flours has been increasing due to consumer demands, which raises new challenges for the management of stored product insects since little is known about the susceptibility of these flours to infestation. Here we measured oviposition and development of Tribolium castaneum, the red flour beetle, a major pest of wheat and rice mills, on 18 different commercially available flours (almond, amaranth, barley, buckwheat, cassava, coconut, corn, garbanzo, millet, oat, potato, quinoa, rice, rye, sorghum, spelt, teff, and wheat) to assess the level of risk. The average number of eggs laid was highest for teff flour, with wheat, rice, buckwheat, sorghum, barley, rye, and spelt flour also having high oviposition. The lowest oviposition was for potato, quinoa, amaranth and cassava. Holding the eggs laid in these flours and evaluating the ability to develop to the adult stage demonstrated that the average number of adult progeny was highest for teff and wheat, followed by buckwheat, rye, oat, spelt, and millet. In an experiment where single eggs were placed directly in flour, the highest percentage development was in barley, buckwheat, sorghum, spelt, teff, and wheat. Time for 50% of single eggs to develop to adults was quickest for sorghum, spelt, teff, and wheat, while sorghum, buckwheat, corn, spelt, and barley had the quickest development of 90% of eggs to reach adults. There was substantial variation among the different flours which indicates variation in risk of insect infestation. As consumer interest in these flours continues to grow and these alternative flours become more prevalent in food facilities, understanding what diets insects successfully infest is critical to developing management tools.
Alison R. Gerken; James F. Campbell. Oviposition and Development of Tribolium Castaneum Herbst (Coleoptera: Tenebrionidae) on Different Types of Flour. Agronomy 2020, 10, 1593 .
AMA StyleAlison R. Gerken, James F. Campbell. Oviposition and Development of Tribolium Castaneum Herbst (Coleoptera: Tenebrionidae) on Different Types of Flour. Agronomy. 2020; 10 (10):1593.
Chicago/Turabian StyleAlison R. Gerken; James F. Campbell. 2020. "Oviposition and Development of Tribolium Castaneum Herbst (Coleoptera: Tenebrionidae) on Different Types of Flour." Agronomy 10, no. 10: 1593.
BACKGROUND Prevention is the first line of defense to mitigating losses of post‐harvest crops. Long‐lasting insecticide treated netting (LLIN) could be used in food facilities to expose insects to insecticide at different areas within a facility. Prior research has shown that single short exposures reduce movement and longer exposures increase mortality for stored‐product insect pests, but we do not know how multiple short duration exposures and biotic and abiotic conditions affect insects exposed to LLIN. Here, we repeatedly exposed red flour beetles, Tribolium castaneum, to LLIN to assess cumulative effects. We also examined effects of beetle age and time of day during exposure and temperature, humidity, and food availability during recovery after a single exposure to LLIN. RESULTS We found that four repeated 10‐minute exposures had similar knockdown as a single 30‐min exposure time. We also found that beetles were more affected when aged 1–6 d versus 14–20 d or exposed mid‐ or late‐day versus earlier in the day. Higher recovery levels were observed with food and at higher relative humidity. In addition, older beetles were more active than younger beetles during exposure, which could reduce contact time with netting and partially explain why older beetles tended to be less affected. CONCLUSION Thus, some individuals can recover after exposure to LLIN dependent on exposure duration and environmental factors, but our study shows that sublethal effects likely persist and future work should consider the physiology of T. castaneum before, during, and after exposure to LLIN.
Alison R. Gerken; Erin D. Scully; James F. Campbell; William R Morrison. Effectiveness of long‐lasting insecticide netting on Tribolium castaneum is modulated by multiple exposures, biotic, and abiotic factors. Pest Management Science 2020, 77, 1235 -1244.
AMA StyleAlison R. Gerken, Erin D. Scully, James F. Campbell, William R Morrison. Effectiveness of long‐lasting insecticide netting on Tribolium castaneum is modulated by multiple exposures, biotic, and abiotic factors. Pest Management Science. 2020; 77 (3):1235-1244.
Chicago/Turabian StyleAlison R. Gerken; Erin D. Scully; James F. Campbell; William R Morrison. 2020. "Effectiveness of long‐lasting insecticide netting on Tribolium castaneum is modulated by multiple exposures, biotic, and abiotic factors." Pest Management Science 77, no. 3: 1235-1244.
Extreme temperature has been used as an alternative to chemical treatments for stored product pests for years. Resistance to heat or cold treatments has not been documented in stored product insects, but repeated use of ineffective treatments could lead to adaptive tolerance. Trogoderma variabile (Dermestidae) is a common pest of stored products, and the larval stage is highly resistant to cold and destructive. We artificially selected populations by inducing chill coma at four different cold temperature treatments: 3 and 5 h at −10°C and 3 and 5 h at 0°C. Recovery time was highly heritable after selection for seven generations for decreased recovery time (cold tolerance) and increased recovery time (cold susceptibility) at all time and temperature combinations. Three replicate populations for each time and temperature combination varied substantially, suggesting different mutations in each population were probably responsible for selected phenotypes. Body size decreased in populations selected for cold susceptibility compared with those selected for cold tolerance and survivorship to long-term cold stress increased in the cold-tolerant populations compared with the susceptible populations. After the cessation of the selection experiment, cold tolerance dissipated within four generations from the populations at −10°C, but was maintained in populations exposed to 0°C. Our results suggest that warehouse beetles can adapt to cold stress quickly, but in the absence of cold stress, the proportion of cold-tolerant/susceptible individuals is quickly reduced, suggesting that some of the mutations responsible for these phenotypes may be associated with fitness costs under normal conditions.
Alison R Gerken; Shelby R Abts; Erin D Scully; James F Campbell. Artificial Selection to a Nonlethal Cold Stress in Trogoderma variabile Shows Associations With Chronic Cold Stress and Body Size. Environmental Entomology 2020, 49, 422 -434.
AMA StyleAlison R Gerken, Shelby R Abts, Erin D Scully, James F Campbell. Artificial Selection to a Nonlethal Cold Stress in Trogoderma variabile Shows Associations With Chronic Cold Stress and Body Size. Environmental Entomology. 2020; 49 (2):422-434.
Chicago/Turabian StyleAlison R Gerken; Shelby R Abts; Erin D Scully; James F Campbell. 2020. "Artificial Selection to a Nonlethal Cold Stress in Trogoderma variabile Shows Associations With Chronic Cold Stress and Body Size." Environmental Entomology 49, no. 2: 422-434.
Insects can infest facilities that house and process post-harvest grains and grain-based products. Integrated pest management tactics rely on tracking insect populations and using this information to select and target management tactics. Our ability to predict when and where to best focus treatment relies on an understanding of long-term trends, but often any available monitoring data are limited in its duration. Here we present data collected over a 10-year period at a flour mill in the central part of the United States. Using traps placed both inside and outside a flour mill and baited with pheromone-lures for Plodia interpunctella (Hübner), Indianmeal moth, and Trogoderma variabile Ballion, warehouse beetle, we examine environmental and spatial variability in insect captures. We find that both species, inside and outside the mill, are highly influenced by seasonal patterns, with peaks of insect captures during the warm season (April through September). There is also consistency across time and space in trap capture for P. interpunctella with traps in an open location consistently capturing high numbers of insects. In contrast, T. variabile lacked consistency in trap capture but were most often not found in the same trap locations as P. interpunctella. Fumigations conducted within the facility appeared to have little impact on insect captures inside, with dynamics appearing to be driven more by broader seasonal patterns in activity. These data and analyses suggest that there is a larger population of these insects that are readily moving in and out of the structures, while fumigation treatments are only impacting a small portion of the overall population and tactics targeting immigration may be an important addition to the pest management program.
Alison R. Gerken; James F. Campbell. Using Long-term Capture Data to Predict Trogoderma variabile Ballion and Plodia interpunctella (Hübner) Population Patterns. Insects 2019, 10, 93 .
AMA StyleAlison R. Gerken, James F. Campbell. Using Long-term Capture Data to Predict Trogoderma variabile Ballion and Plodia interpunctella (Hübner) Population Patterns. Insects. 2019; 10 (4):93.
Chicago/Turabian StyleAlison R. Gerken; James F. Campbell. 2019. "Using Long-term Capture Data to Predict Trogoderma variabile Ballion and Plodia interpunctella (Hübner) Population Patterns." Insects 10, no. 4: 93.
The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a major pest of facilities where grain is processed because of its ability to find and colonize food resource patches. Traps baited with pheromone and kairomone lures are commonly used to monitor for the presence of insects in warehouses or flour mills, for example. However, two nonmutually exclusive components, environment and genetics, could influence insect responsiveness to volatiles, impacting the efficacy of monitoring. Intraspecific variation in attraction behavior to food and mates is largely unexplored in stored-product insects, but tapping into natural genetic variation could provide a baseline for identifying genetic mechanisms associated with finding resources. Here, we assess eight strains of T. castaneum for variation in response to kairomone- and pheromone-based lures using three behavioral assays: paired choice with no forced air flow, upwind attraction with forced air flow, and movement pattern in an arena with a single odor source. We find strain-specific responses to kairomones and pheromones and evidence for heritability in behavioral responses. However, environmental coefficients for behavioral responses to both lures are high, suggesting that environment, and its potential interaction with genotype, strongly influences behavioral outcomes in these assays. Furthermore, despite the different environmental conditions among the different behavioral assays, we find a correlation for volatile preference among the assays. Our results provide a baseline assessment of natural variation for preference to kairomone and pheromone lures and suggest that careful consideration of behavioral assay is key to understanding the mechanisms of attraction in these stored-product pests.
Alison R Gerken; Erin D Scully; James F Campbell. Red Flour Beetle (Coleoptera: Tenebrionidae) Response to Volatile Cues Varies With Strain and Behavioral Assay. Environmental Entomology 2018, 47, 1252 -1265.
AMA StyleAlison R Gerken, Erin D Scully, James F Campbell. Red Flour Beetle (Coleoptera: Tenebrionidae) Response to Volatile Cues Varies With Strain and Behavioral Assay. Environmental Entomology. 2018; 47 (5):1252-1265.
Chicago/Turabian StyleAlison R Gerken; Erin D Scully; James F Campbell. 2018. "Red Flour Beetle (Coleoptera: Tenebrionidae) Response to Volatile Cues Varies With Strain and Behavioral Assay." Environmental Entomology 47, no. 5: 1252-1265.
Stored products represent an enormous economic output, but insects regularly immigrate into stored products from the surrounding landscape throughout the postharvest supply chain. Long-lasting insecticide-incorporatednetting (LLIN), which usually contains an incorporated pyrethroid, has been used as part of a strategy to reduce the spread of malaria in tropical regions since the 1990s and has only recently been considered for its application in pre- and postharvest agricultural contexts. The goal of this study was to determine how short-term exposure to LLINs in the laboratory impacts the locomotory behavior and mortality for adult Tribolium castaneum (Herbst), (Coleoptera: Tenebrionidae) red flour beetle, and Rhyzopertha dominica (Fauvel), (Coleoptera: Bostrichidae) lesser grain borer, at different periods of time after exposure. Exposure to LLINs resulted in multiple-fold reductions in the distance moved and elevated angular velocity in both species that quickly took effect and persisted even after 168 h compared with adults exposed to control netting. R. dominica was somewhat more susceptible than T. castaneum to LLINs. Finally, the dispersal capacity of both species, measured as ability to move to a remote resource patch, was significantly impaired or absent after exposure to LLINs compared to adults exposed to control netting. Our results demonstrate that LLINs are a promising new technology for reducing infestation by stored product insects since even short exposures limit movement and ultimately lead to knockdown and death.
William R Morrison; Rachel V Wilkins; Alison R Gerken; Deanna Scheff; Kun Yan Zhu; Frank H Arthur; James F Campbell. Mobility of Adult Tribolium castaneum (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (Coleoptera: Bostrichidae) After Exposure to Long-Lasting Insecticide-Incorporated Netting. Journal of Economic Entomology 2018, 111, 2443 -2453.
AMA StyleWilliam R Morrison, Rachel V Wilkins, Alison R Gerken, Deanna Scheff, Kun Yan Zhu, Frank H Arthur, James F Campbell. Mobility of Adult Tribolium castaneum (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (Coleoptera: Bostrichidae) After Exposure to Long-Lasting Insecticide-Incorporated Netting. Journal of Economic Entomology. 2018; 111 (5):2443-2453.
Chicago/Turabian StyleWilliam R Morrison; Rachel V Wilkins; Alison R Gerken; Deanna Scheff; Kun Yan Zhu; Frank H Arthur; James F Campbell. 2018. "Mobility of Adult Tribolium castaneum (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (Coleoptera: Bostrichidae) After Exposure to Long-Lasting Insecticide-Incorporated Netting." Journal of Economic Entomology 111, no. 5: 2443-2453.
Comparing methodologies that attempt to mimic natural conditions is important when evaluating thermal tolerances of ectotherms, as exposing animals to different artificial thermal regimes may provide conflicting information of an insect's thermal profile. Rapid cold hardening (RCH) occurs in ectotherms and typically increases survivorship to extreme cold exposure through a short, pre-treatment to a non-lethal cold temperature. Here we assess survivorship in a set of genotypes from the Drosophila melanogaster Reference Panel for direct and ramping RCH pre-treatments at cooling rates occurring under more natural conditions (0.1 °C/min and 0.5 °C/min) in combination with a direct and ramped rewarming treatment post cold exposure. We find that all three pre-treatment exposures alone significantly increase survivorship. We find significant correlations in survivorship among treatments across genotypes, suggesting that regardless of the pre-treatment, individuals of a given genotype have an innate level of acclimation. When rewarming is introduced, survivorship significantly decreased relative to pre-treatment alone and correlations of survival between phenotypes were not significant. Our results suggest that rewarming and slow RCH are costly to survival while a quicker RCH may impart physiological benefits more consistently across genotypes.
Alison R. Gerken; Olivia Eller; Theodore Morgan. Speed of exposure to rapid cold hardening and genotype drive the level of acclimation response in Drosophila melanogaster. Journal of Thermal Biology 2018, 76, 21 -28.
AMA StyleAlison R. Gerken, Olivia Eller, Theodore Morgan. Speed of exposure to rapid cold hardening and genotype drive the level of acclimation response in Drosophila melanogaster. Journal of Thermal Biology. 2018; 76 ():21-28.
Chicago/Turabian StyleAlison R. Gerken; Olivia Eller; Theodore Morgan. 2018. "Speed of exposure to rapid cold hardening and genotype drive the level of acclimation response in Drosophila melanogaster." Journal of Thermal Biology 76, no. : 21-28.
Controlling postharvest pest species is a costly process with insecticide resistance and species‐specific control requiring multiple tactics. Mating disruption (MD) can be used to both decrease a female's access to males and delay timing of mating and decreases overall mating success in a population and population growth rate. Development of new commercially available MD products requires an understanding of life history parameters associated with mating delay. These can provide information for targeting proportions of reproducing individuals using MD. After delaying mating for females of two closely related beetle species, Trogoderma variabile and T. inclusum, we surveyed survivorship, number of eggs laid, and number of progeny emerged. With increases in mating age, total number of eggs laid and total number of progeny emerged significantly declined over time. T. inclusum typically had greater numbers of eggs laid and progeny emerged compared to T. variabile as female age at mating increased, suggesting that T. inclusum may be more resistant to long‐term delays in mating. Life span showed an increase as mating age increased but life span significantly decreased almost immediately following mating. Simulations depicting multiple distributions of mating within a population suggest that in a closed population, high levels of mating delay significantly reduced reproductive growth rates. Although reproductive growth rates were decreased with increased mating age, they are still large enough to maintain populations. This study highlights the differences in life history between two closely related species, suggesting that T. inclusum outperforms T. variabile over the course of a life span, but T. variabile has better reproductive capabilities early in life. MD may also be a viable component of a pest management system for these two species as it significantly decreased overall reproductive output and population growth.
Alison R. Gerken; James F. Campbell. Life history changes in Trogoderma variabile and T. inclusum due to mating delay with implications for mating disruption as a management tactic. Ecology and Evolution 2018, 8, 2428 -2439.
AMA StyleAlison R. Gerken, James F. Campbell. Life history changes in Trogoderma variabile and T. inclusum due to mating delay with implications for mating disruption as a management tactic. Ecology and Evolution. 2018; 8 (5):2428-2439.
Chicago/Turabian StyleAlison R. Gerken; James F. Campbell. 2018. "Life history changes in Trogoderma variabile and T. inclusum due to mating delay with implications for mating disruption as a management tactic." Ecology and Evolution 8, no. 5: 2428-2439.
RNA interference (RNAi) is a functional genomics tool to correlate genotype and phenotype by delivering targeted, gene-specific, and complementary dsRNA into a host via injection, feeding, or other means in order to reduce gene expression. In the red flour beetle, Tribolium castaneum, RNAi has been successful via injected dsRNA at all life stages. Traditionally, successful transcript knockdown has been quantified by qPCR on a gene-by-gene basis, where only expression of the target gene and normalization genes are evaluated. In this study, RNA-Seq was used to quantify transcript expression in larvae injected with dsRNA for aspartate 1-decarboxylase (ADC), which gives a reliable phenotype of an adult with a black cuticle instead of the wild-type red-brown. ANOVA of control, mock-injected, and ADC-dsRNA injected larvae indicated that target gene expression was significantly (P = 0.002) reduced 4-fold, and the black phenotype was achieved in all adults injected with ADC-dsRNA as larvae. In a pairwise analysis, significant (P < 0.05) differential expression of other genes in ADC-injected larvae suggested connections between gene pathways. One gene, dopamine receptor 2, was increased in expression 227-fold (P = 0.025), presumably connected to previous data that showed a reduction in expression of ADC results in increased levels of dopamine. To evaluate the hypothesis that increased dopamine levels can affect mobility, T. castaneum adults injected with ADC-dsRNA as larvae were significantly impaired in movement tests compared to controls, similar to black mutants in Drosophila melanogaster. The data demonstrate that RNA-Seq can reveal gene connectivity and provide more complete data validation and analysis compared to qPCR.
Lindsey C. Perkin; Alison R. Gerken; Brenda Oppert. RNA-Seq Validation of RNAi Identifies Additional Gene Connectivity in Tribolium castaneum (Coleoptera: Tenebrionidae). Journal of Insect Science 2017, 17, 1 .
AMA StyleLindsey C. Perkin, Alison R. Gerken, Brenda Oppert. RNA-Seq Validation of RNAi Identifies Additional Gene Connectivity in Tribolium castaneum (Coleoptera: Tenebrionidae). Journal of Insect Science. 2017; 17 (2):1.
Chicago/Turabian StyleLindsey C. Perkin; Alison R. Gerken; Brenda Oppert. 2017. "RNA-Seq Validation of RNAi Identifies Additional Gene Connectivity in Tribolium castaneum (Coleoptera: Tenebrionidae)." Journal of Insect Science 17, no. 2: 1.
Seasonal and daily thermal variation can limit species distributions because of physiological tolerances. Low temperatures are particularly challenging for ectotherms, which use both basal thermotolerance and acclimation, an adaptive plastic response, to mitigate thermal stress. Both basal thermotolerance and acclimation are thought to be important for local adaptation and persistence in the face of climate change. However, the evolutionary independence of basal and plastic tolerances remains unclear. Acclimation can occur over longer (seasonal) or shorter (hours to days) time scales, and the degree of mechanistic overlap is unresolved. Using a midlatitude population ofDrosophila melanogaster, we show substantial heritable variation in both short- and long-term acclimation. Rapid cold hardening (short-term plasticity) and developmental acclimation (long-term plasticity) are positively correlated, suggesting shared mechanisms. However, there are independent components of these traits, because developmentally acclimated flies respond positively to short-term acclimation. A strong negative correlation between basal cold tolerance and developmental acclimation suggests that basal cold tolerance may constrain developmental acclimation, whereas a weaker negative correlation between basal cold tolerance and short-term acclimation suggests less constraint. Using genome-wide association mapping, we show the genetic architecture of rapid cold hardening and developmental acclimation responses are nonoverlapping at the SNP and corresponding gene level. However, genes associated with each trait share functional similarities, including genes involved in apoptosis and autophagy, cytoskeletal and membrane structural components, and ion binding and transport. These results indicate substantial opportunity for short-term and long-term acclimation responses to evolve separately from each other and for short-term acclimation to evolve separately from basal thermotolerance.
Alison R. Gerken; Olivia Eller; Daniel A. Hahn; Theodore Morgan. Constraints, independence, and evolution of thermal plasticity: Probing genetic architecture of long- and short-term thermal acclimation. Proceedings of the National Academy of Sciences 2015, 112, 4399 -4404.
AMA StyleAlison R. Gerken, Olivia Eller, Daniel A. Hahn, Theodore Morgan. Constraints, independence, and evolution of thermal plasticity: Probing genetic architecture of long- and short-term thermal acclimation. Proceedings of the National Academy of Sciences. 2015; 112 (14):4399-4404.
Chicago/Turabian StyleAlison R. Gerken; Olivia Eller; Daniel A. Hahn; Theodore Morgan. 2015. "Constraints, independence, and evolution of thermal plasticity: Probing genetic architecture of long- and short-term thermal acclimation." Proceedings of the National Academy of Sciences 112, no. 14: 4399-4404.