Entomology

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Research from the Department of Entomology. The department is part of the School of Natural Resources, and their website may be found at https://www.ndsu.edu/snrs/

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Aphid Interactions with Environmental Variation in the Field and Lab
(North Dakota State University, 2015) McLean, Erin Leigh
A basic tenet of ecology is that organisms are affected by both abiotic factors and other organisms; therefore, there is value in understanding interactions in our changing world. Aphids are model organisms for questions regarding many interactions. I explored three aphid-centered studies. (1) Rearing aphids in a certain temperature changed their response to exposure to different temperatures. Short term exposure to warmer temperatures increased fecundity, but being raised in higher temperatures lowered fecundity across treatments. (2) Feeding on aphids by lady beetles in the lab was measured after exposure to varying temperatures with or without prey. Warming without prey was detrimental, but warming while continually fed invoked more predation than the cooler temperature. (3) Soybean aphids, natural enemies, and other pests vary in space and time. We surveyed soybean to explore the effect of field locations, management, and year on arthropod community structure and found a predominant year effect.
Behaviors Mediate Aphid Interactions with Natural Enemies and the Environment
(North Dakota State University, 2016) Kopco, James
Behavior is a crucial component of ecology that mediates how animals interact with one another and with the environment. Behaviors can allow animals to avoid the harmful effects of things like competition, predation, and extreme abiotic conditions. However, animals often have constraints that limit the potential benefits of their behaviors, so we addressed what factors contribute to these constraints in plant-aphid-wasp systems. Parasitoids of aphids are tiny wasps that lay their eggs in aphids, where the larva feeds and develops. Each aphid can only sustain a single parasitoid, so parasitoids mark aphids when they lay an egg to discourage others from laying additional eggs. Not all parasitoids mark aphids the same way, and whether species with different marks can recognize one another’s mark was unclear. We found that parasitoids with different marks fail to respond to one another’s marks. Because these parasitoids laid eggs in aphids that were already parasitized, competition between them will occur through mortal combat between the larvae rather than egg-laying restraint in the adults. Parasitoid attack induces aphid behaviors such as fighting, running away, or dropping off the host plant. These behaviors can deter or evade the attacker, but they cost the aphid an opportunity to feed. This feeding interruption decreases the number of offspring the aphids produce. When aphids run from a threat, they usually resettle on the newest leaves of a plant, where their reproduction is enhanced. However, when they drop from a plant to escape, they resettle randomly and do not benefit from the better location, indicating that more vigorous responses can lose benefits. We also showed that aphids exhibit similar movement and resettling behaviors when disturbed by heat shocks. However, this behavior did not affect aphid reproduction or survival when induced by a heat shock. While movement to new leaves appears to be a general response to several disturbances, its benefits to aphids only occur in specific situations. We have shown that behaviors can be constrained by unfamiliar stimuli and the general context in which they are invoked. These constraints can dictate how insects interact with each other and the environment.
Collection and Analysis of Volatiles of Various Cultivated Sunflower, Helianthus Annuus, (Asteraceae) Germplasm and Investigation of Some Aspects of Host Selection in Adult Red Sunflower Seed Weevil, Smicronyx Fulvus L., (Coleoptera Curculionidae)
(North Dakota State University, 2017) Lokumana, Charithra Rathnamali
Plants of sunflower germplasm putatively resistant or susceptible to the red sunflower seed weevil, Smicronyx fulvus (Coleoptera: Curculionidae) were used to test the hypothesis that the volatile composition of these two types are different and may influence acceptance/rejection of sunflower germpalsm by S. fulvus. At least 13 volatile terpenoids were released by the different plant lines, with some varying in concentration according to plant line, head maturity, and time of day. Comparison between resistant and susceptible plant lines showed differences in concentrations of less abundant compounds (3E)-4,8-dimethyl-1-3-7-nonatriene, α-copaene, bornyl acetate, β-elemene, β-selinene and germacrene-D, indicating that, one or more of these compounds may be useful markers for resistance/susceptibility to S. fulvus. In behavioral binary choice bioassays, S. fulvus adults were attracted to sunflower heads, preferring R5.5 over R4 and R6 heads, and susceptible to resistant plants. Video recordings indicated both volatile and contact chemicals may be involved in host acceptance/rejection.
Conspectus of Aeptini Stål, 1871 (Hemiptera: Heteroptera: Pentatomidae: Pentatominae)
(North Dakota State University, 2017) Faúndez, Eduardo I
The Pentatominae tribe Aeptini is revised. A key to the known genera is provided, together with redescription and figures. The genus Paramenestheus is revised, including a key to the species and figures to all the included taxa. Two new genera and eight new species are discovered and described. A phylogenetic analysis is included for the Aeptini, with two approaches, cladistic and maximum likelihood, both morphologically based. After these analysis it is concluded that it is a monophyletic tribe and has to be split into two subtribes: Aeptina (including Aeptus and Eribotes) and Menesthina (including Aeliosoma, Hillieria, Menestheus, Paramenestheus, Pseudaelia, New Genus 1, New Genus 2.). Diagnoses for both subtribes are included. Biogeographically it is hypothesized that the Aeptini have a Gondwanian origin which explains it current disjunct distribution in Africa and Australia. The importance of the findings on this dissertation, as well as the relationships among Aeptini and other Pentatominae groups is commented and disccused. Special reference is made to the importance of the presence of a mesosternal sulcus as a major character that may lead to a reclassification of the Pentatominae, having the Aeptini as one of the basal groups. After all the changes proposed on this dissertation the Aeptini is now comprised of two subtribes, nine genera and 30 species.
Crop and Prairie Grasses Serving as Hosts for the Hessian Fly
(North Dakota State University, 2012) Li, Yue
Insect herbivores typically parasitize a relatively small number of plant species. Host specialization is presumed to be a result of evolutionary arms races, with insect adaptations ultimately restricting host range. Being a gall-maker, the Hessian fly has highly evolved interactions with plant hosts. As a consequence, its host range is expected to be narrow. Two crop species, wheat and barley are hosts of the Hessian fly. I studied whether non-crop grasses can also serve as hosts. Included in tests were seven grass species that are important components of the grasslands of the Northern Great Plains. Although less suitable than wheat and barley, all seven species received eggs and five of the seven species supported development of offspring to the adult reproductive stage. Results indicate a broader host range than was expected. A benefit of being able to use non-crop grasses is availability of alternate hosts when superior crop hosts are not available.
Density and Movement of Soybean Aphid, Aphis Glycines (Hemiptra: Aphididae) in Response to Temperature and Resistant Soybean Plants
(North Dakota State University, 2012) Whalen, Rebecca Ann
Movement is one way herbivores respond to their host plant, yet the movement of relatively immobile insects has received little attention. We studied how the movement and density of apterous soybean aphids responds to a resistant soybean variety and different temperatures. In Chapter One, we examined aphid movement both within and between soybean plants that varied in their resistance to aphids. Aphids on resistant plants had a wider dispersal, apparently due to greater aphid movement. Consequently, aphids on resistant plants could move to neighboring susceptible plants, thereby increasing their density. In Chapter Two, we measured aphid density and dispersal on resistant and susceptible plants when insects and plants were exposed to two different temperatures. Here, movement behavior was affected by both plant resistance and temperature. Moreover, temperature and plant resistance interacted to influence aphid density. Our results indicate the important role that movement can play in an herbivore's response to plant resistance.
Effect of Larval Diet on Endogenous Carbon Reproductive Resources of Fifth Instars and Adult Females of the Moth, Heliothis Virescens
(North Dakota State University, 2013) Suman, Smita Dutta
Mostly adult Lepidoptera feed on plant nectar. That is, adults can only contribute to carbon, and not nitrogen, acquisition. The moth Heliothis virescens were used to explore the hypothesis that larval nutrition influences various adult carbon pools and that these, in turn, may affect pheromone production quantitatively. H. virescens larvae were reared on diets differing in carbohydrate, fat or protein content and resulting 5 th instars and adults were analyzed for carbon pools, hemolymph trehalose concentration (HTC) and lipid content. Across all the diet treatments, changes in carbohydrate content affected carbon pool the most. In particular, for insects reared on a high carbohydrate diet, adults had a greater lipid content, while for insects reared on a low carbohydrate diet, adults had a lower HTC, compared to insects reared on the control or other diets. By contrast, changes in protein and fat had little effect on HTC and lipid content of adults.
The Effects of Abiotic Climate Change Factors on Aphid Life History and Populations
(North Dakota State University, 2015) Alfonso, Joseph Vincent
While the effects of many abiotic factors associated with climate change have not been extensively studied, work on model organisms is beginning to help predict effects on similar species. Research on climate change has been dominated by temperature effects on organisms, but additional factors are being studied, including changes in atmospheric CO2 concentrations, wind patterns, precipitation patterns, ultra-violet (UV) radiation, night-time temperatures, and daily high temperatures (heat shocks). We review these effects on aphids and present experimental findings on the effects of night-time warming on pea aphid population growth and birth rates. Aphid populations changed when warmed at different times of a day (overnight vs. during the day), but changes to individual aphid birth rate were not responsible for the population level pattern. Although the exact mechanism is still unclear, increasing nightly temperatures matters for pea aphid population growth and could influence interactions with other species.
The Effects of Salinity on Herbivorous Pests of Corn and Soybean
(North Dakota State University, 2016) Eichele, Jaclyn Lee
Many environmental factors, including soil characteristics, are critically important for plants, herbivorous arthropods, and their interactions. Despite increasing evidence that soil salinity can drastically impact plants, little is known about how salinity affects the herbivorous arthropod pests feeding on those plants we investigated how soil salinity affects two major crop pests: the two spotted spider mite (Tetranychus urticae) feeding on corn and soybean and the soybean aphid (Aphis glycines) on soybean. We quantified the impact of salinity by measuring demographic characteristics and behavior of pests on plants grown in soil with various levels of salinity. Overall, both crop pests performed better as salinity increased. These studies suggest that salinity can be just as important for herbivores as it is for plants. Moreover, the negative effects of soil salinity on crop plants in agroecosystems may be further compounded by a greater risk of pest problems.
Effects of Temperature on Pea Aphids, their Host Plants, and their Parasitoids
(North Dakota State University, 2018) Valls, Aleix
Temperature has the potential to alter every aspect of an organism’s biology. This is especially true when we focus on small ectotherms such as insects. Understanding the effects of temperature on insects is particularly important given that climate change scenarios predict changes in temperature across the globe. In Chapter 1 we explored the effects of heat shocks on a discrete host-parasitoid interaction, specifically asking what happens if the heat shock happened before, during or after the interaction. We found that heat shocks had a stronger negative effect when they occurred while the wasp was actively foraging. In a follow-up behavioral experiment, we observed that this result is likely caused by the heat shock quickly rendering the majority of wasps inactive. In Chapter 2 we tested how variation in temperature affects pea aphid population size and how the effect changes with average temperature. We compared the population size of pea aphids under constant and fluctuating temperature profiles across a cool temperature range (20C and 16C/24C) and a warm temperature range (28C and 24C/32C). We saw that in the cooler range, pea aphids in the constant and fluctuating temperature treatments had the same population size. However, the same was not true for the warmer temperatures. In that case, fluctuating temperature profiles produced smaller populations compared to the constant temperatures. In Chapter 3 we focused on the possible indirect effects of temperature on pea aphids mediated by the aphids’ host plants. We performed five experiments where we manipulated the exposure temperature (16C, 24C, and 32C) for plants and aphids. While temperature had strong direct effects on aphids and also affected plant size, temperature had little to no indirect effects on pea aphid fecundity. While the idea of temperature change can seem straightforward, temperature effects on insects are not straightforward. Timing and variation of temperature change are important. Indirect effects though direct effects on hosts also are important. My work shows a number of approaches for investigating these different temperature effects to better understand what might happen to insects when climate changes.
Exploring Effects of Weed Management in Agroecosystems: Arthropods, Soil Properties and Soybean Production
(North Dakota State University, 2014) Hansen, Ashton Anne
Soil-dwelling arthropods contribute to agroecosystems, but it’s unclear how specific taxa respond to weed management practices. Objectives were to explore 1) response of Collembola to weed management in a glyphosate-tolerant soybean system and 2) impacts of weed management and soil arthropod reduction (via insecticide) on soil and plant parameters. Weed management had variable effects on Collembola, whereas location had a consistent effect on diversity and density. Increased weed pressure decreased soil nitrate and reduced soybean yield. Reduction of soil arthropods didn’t impact soil nitrate or yield, but increased the number of soybean root nodules. This could be due to decreased root herbivores, or overcompensation of the plant. Previous research emphasized effects of plant communities on soil arthropods, but our study suggests soil properties strongly influence arthropod communities. Although this study does not show obvious benefits of soil arthropods, long term insecticide application may be detrimental to crop production.
A Faunal Survey of Coleoptera, Hemiptera (Heteroptera), and Lepidoptera Associated with Fraxinus Pennsylvanica Marshall (Oleaceae) in the Red River Valley of Eastern North Dakota
(North Dakota State University, 2014) Walker, James Samuel
The emerald ash borer (Agrilus planipennis; EAB) is an invasive wood-boring beetle causing mortality of ash trees in North America. This project was initiated because of the threat of EAB moving into North Dakota. The main objective was to establish a baseline of insects associated with ash (Fraxinus) in the Red River Valley of North Dakota before EAB arrives. Taxonomic groups focused on include: Coleoptera, Hemiptera (Heteroptera), and Lepidoptera. Ten sites were surveyed regularly. Sites were chosen due to their ash content: nine sites contained green ash (Fraxinus pennsylvanica), and one site contained black ash (F. nigra). Surveying was performed during the months of May through September in 2010 and 2011. Overall, 4,301 specimens from 53 families in three orders were identified in this study, totalling at least 276 distinct taxa. 23 of the species collected and identified in this study were found to be associated with Fraxinus.
Geographic Distribution and Effects of Transgenic Corn Hybrids and Chemical Insecticides on Northern and Western Corn Rootworms (Coleoptera: Chrysomelidae) in North Dakota
(North Dakota State University, 2018) Calles Torrez, Veronica
Northern (Diabrotica barberi Smith & Lawrence) and western (D. virgifera virgifera LeConte) corn rootworms are major corn (Zea mays L.) pests in North America. Integrated pest management (IPM) strategies used for corn rootworm control include crop rotation, chemical insecticides, and corn hybrids expressing Bacillus thuringiensis (Bt) toxins. Field and laboratory experiments were conducted between July 2013 and October 2017 to address the following objectives: 1) determine the geographic distribution and densities of D. barberi and D. v. virgifera in North Dakota (ND) and compare the effectiveness of unbaited green ScentryTM Multigard and yellow Pherocon® AM/NB sticky traps for monitoring both species; 2) access the impacts of corn hybrids expressing the Cry3Bb1, Cry34/35Ab1, and Cry3Bb1 + Cry34/35Ab1 proteins, tefluthrin soil insecticide, and clothianidin insecticidal seed treatment on beetle emergence, larval feeding injury, and corn grain yield; and 3) evaluate if either species has developed resistance to these Bt-proteins. Both species were commonly distributed in east-central and southeastern ND, and capture rates ranged from 0 to >10 beetles per trap per week. Green ScentryTM sticky traps captured greater mean numbers of D. barberi beetles in 68% of fields containing this species, while the yellow Pherocon AM/NB trap captured higher mean numbers of D. v. virgifera in 57% of fields containing this species, but their relative trap efficiency was inconclusive. Overall beetle emergence was significantly lower in Bt-protected than in non-Bt corn. Bt hybrids produced higher grain yield and sustained consistently lower levels of larval root-feeding injury than non-Bt in fields with higher rootworm densities. Tefluthrin and clothianidin did not significantly impact beetle emergence or larval root injury. Results also documented the first confirmed field-evolved incomplete resistance in D. barberi populations to Cry3Bb1 and Cry34/35Ab1 proteins. The Ransom population of D. v. virgifera was confirmed as resistant to the Cry3Bb1 toxin. Theses findings indicate reduced efficacy of corn rootworm control using tefluthrin, clothianidin, and Bt corn. Continuously scouting for rootworms using sticky traps or other methods prior to making rootworm management decisions, and the use of an IPM approach to their control is needed to mitigate the development of Bt-resistance rootworms in ND.
IfSAR DTM-derived Predictive Flood Models: A Cost-effective Approach to Target Site- Specific Mosquito (Diptera: Culicidae) Control Efforts
(North Dakota State University, 2016) Stenehjem, Jacquelin J.
The study area is the 400 km2 floodplain and wetlands of the upper Missouri River, located in the northwestern corner of North Dakota, near the community of Williston. Regional climate is semiarid, yet the Williston vector control agency battles large populations of Culicidae nearly every spring and summer. Best mosquito management practices (BMPs) are integrated, relying on a combination of thorough, routine, ground-based sampling and surveillance methods to provide important information on which control strategies and evaluations of effective are based. However, the mosquito breeding habitat near Williston is extensive and contains difficult terrain, which makes standard ground-based sampling and surveillance methods impractical. This study analyzed remotely sensed Interferometric Synthetic Aperture Radar (IfSAR) Digital Terrain Model (DTM) elevation data as a potential alternative for ground-based methods. Remotely sensed IfSAR technology is relative low-cost, has high-spatial resolution, is not limited by inclement weather, and only needs to be collected once if local topography remains stable. IfSAR elevation data provides information needed to model hydrological characteristics such as slope, aspect, water flow direction, and accumulation, important considerations in relation to mosquito control efforts. Predictive flood models, developed in this study from the IfSAR elevation data, make it possible to predict the locations of water accumulation within the floodplain as river elevations fluctuate. A vertical root mean squares error (RMSEz) assessment of the full IfSAR elevation data in all land cover classifications combined was 1.071 m, consistent with the vendor’s stated RMSEz of 1 meter. The vertical accuracy of the full IfSAR data was 2.099 meters at the 95% confidence level and is consistent with the 95th percentile accuracy of 2.211 meters. The frequency distribution of errors was generally normal. This study determined that airborne, high-resolution IfSAR DTM-elevation data can serve as an alternative for ground-based sampling and surveillance methods and provide a needed decision support system (DSS) tool to the local vector control agency. The predictive flood models are a new approach for predicting the locations of accumulated water within the floodplain will decrease vector control response time and improve the targeting of site-specific control efforts, which in turn, will decrease overall costs for these services.
Oviposition Preference and Larval Host Range of the Sugarbeet Root Maggot
(North Dakota State University, 2012) Msangosoko, Kondwani Richmond
The sugarbeet root maggot, Tetanops myopaeformis Röder, is native to North America; however, its main crop host, sugarbeet, Beta vulgaris L., was introduced to the continent from Europe. This study involved an investigation of the attractiveness of cultivated crops and native North American weed species for oviposition by T. myopaeformis and the relative suitability of these potential host plant species for larval development, thus potentially shedding light on the native and current host range of this pest. Females preferred to oviposit near the following plant species: sugarbeet; spinach, Spinacia oleroceae L.; palmer amaranth, Amaranthus palmeri S. Watts.; common lambsquarters, Chenopodium album L.; redroot pigweed, Amaranthus retroflexus L.; and spear saltbush, Atriplex patula L. Larval survival was highest on spinach, followed by sugarbeet, and spear saltbush (all belonging to the family Chenopodiaceae). This suggests that species within this family likely served as native host plants for T. myopaeformis before the introduction of sugarbeet to North America. Lower larval numbers on common lambsquarters, redroot pigweed, and Palmer amaranth suggest that these species are sub-optimal hosts, despite being attractive for oviposition. Additional findings showed a general lack of oviposition preference by T. myopaeformis females for sunflower, Helianthus annuus L., and common ragweed, Ambrosia artemisiifolia L. These results provide further insights into the rapidly successful host preference shift by this insect to sugarbeet.
Pest Management of Wheat Stem Sawfly, Cephus Cinctus Norton (Hymenoptera: Cephidae), in Western North Dakota
(North Dakota State University, 2012) Stegmiller, Joseph
The wheat stem sawfly, Cephus cinctus Norton, is regarded as a major pest of dryland wheat in the Upper Great Plains. For peak emergence of wheat stem sawfly, the most accurate base was 0 C using air temperature, and then degree-day base of 0 C using soil temperatures. For Bracon cephi, the most accurate base temperature was the lower degree-day base using air (0 C) and soil (0 C) temperatures. The solid-stemmed varieties, Mott and Choteau, exhibited the highest stem solidity and also experienced the lowest percentage of wheat stem sawfly damaged stems. The hollow-stemmed varieties, Glenn, Reeder and Steele ND, had the lowest levels of solidity and usually the highest percentage of wheat stem sawfly damaged stems. When wheat stem sawfly populations were high, the solid-stemmed wheat varieties, Mott and Choteau, had yield, test weight, and protein that were comparable to the hollow-stemmed varieties, Glenn, Reeder and Steele ND.
The Tingidae (Hemiptera: Heteroptera) of Southern Central America (with an Emphasis on Costa Rica)
(North Dakota State University, 2018) Knudson, Alexander
The genera of Tingidae of the neotropics are herein diagnosed and a key for their identification is also provided. Five new genera are described from Central America, two from Panama, two from Costa Rica, and one new genus is described from Mexico. This brings the total of neotropical genera to 74. One new species, Mexibyrsa woolleyi is described from Mexico. The Tingidae of southern Central America (Nicaragua, Costa Rica, and Panama) are reviewed in detail. There are now 153 described species spread among 43 genera. Thirty-two new species from southern Central America are described. Identification keys are provided for all species found in the study region.
The Wheat-Hessian Fly Interaction: Co-Evolution and Ecology in an Economically Important Plant-Insect System
(North Dakota State University, 2013) Anderson, Kirk Mitchel
The study of wheat’s H-gene mediated resistance to Hessian flies examined the cost of the constitutively expressed H-gene which functions in the plant’s surveillance system and the cost of the downstream induced response. For the constitutively-expressed H-gene, some measures indicated costs, but a greater number indicated benefits. For the induced resistance, plants showed benefits of being attacked. It is expected that fitness costs play a role in determining the rate at which plant defense evolves, and it is important for agriculture as plant breeders decide whether to pyramid resistance genes into a single cultivar to prevent the evolution of pest virulence. Before plant breeders undertake the effort to transfer resistance into crop cultivars, it must be asked: is the pest a sufficient threat to warrant the effort? To answer this question, the recently discovered female-produced sex pheromone of the Hessian fly was used to explore the pest potential for populations in the Upper Great Plains. Methods for pheromone trapping were established and trapping data were used to explore geographic distribution, phenology, and insect density. It was concluded that the Hessian fly is a risk to wheat in the Upper Great Plains and it was predicted that global warming and the increased cultivation of winter wheat will add to this risk. If Hessian flies are a sufficient threat to the region’s wheat crop, which of the 33 known resistance gene(s) should be used? To answer this question, traditional biotyping and an assay of all available H-genes were used to provide information on the virulence of a population of Hessian flies from the Upper Great Plains. The results were surprising as far more virulence was encountered than was expected. Using traditional virulence testing thirteen of the 16 possible Hessian fly biotypes were present in the North Dakota population, and in the assay of all available H-genes few gave 100% protection. In addition to information on Hessian fly virulence, the studies explored aspects of the wheat-Hessian fly interaction providing details on the fate of the Hessian fly and the wheat plant that have not been examined by other research on Hessian fly virulence.

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