Movement of \u3ci\u3eCicindela hirticollis\u3c/i\u3e Say Larvae in Response to Moisture and Flooding

The larvae of the tiger beetle, Cicindela hirticollis Say, inhabit sandy shoreline areas that flood periodically. This species has declined over much of its range and at least one subspecies is near extinction, possibly as a result of human alteration of waterways. In addition to physiological tolerance for anoxia, the larvae have physical and behavioral adaptations to avoid drowning. We hypothesized that C. hirticollis larvae would exhibit behavioral responses to soil moisture change and flooding because, unlike most other tiger beetles, they frequently relocate their burrows. Our laboratory studies demonstrated that larvae select surface soil moisture levels of 7–50% saturation in which to dig new burrows. Within 96 h of immersion, most larvae abandon burrows and larvae do not form new burrows in darkness. Larvae may relocate when flooded, suggesting a previously undocumented mechanism for dispersal; however, dams often eliminate suitable habitat areas downstream, suggesting that this behavior may be detrimental in riverine populations. Because larvae move during daylight hours, they also are likely to suffer mortality from trampling due to human recreational activity

Movement of \u3ci\u3eCicindela hirticollis\u3c/i\u3e Say Larvae in Response to Moisture and Flooding

The larvae of the tiger beetle, Cicindela hirticollis Say, inhabit sandy shoreline areas that flood periodically. This species has declined over much of its range and at least one subspecies is near extinction, possibly as a result of human alteration of waterways. In addition to physiological tolerance for anoxia, the larvae have physical and behavioral adaptations to avoid drowning. We hypothesized that C. hirticollis larvae would exhibit behavioral responses to soil moisture change and flooding because, unlike most other tiger beetles, they frequently relocate their burrows. Our laboratory studies demonstrated that larvae select surface soil moisture levels of 7–50% saturation in which to dig new burrows. Within 96 h of immersion, most larvae abandon burrows and larvae do not form new burrows in darkness. Larvae may relocate when flooded, suggesting a previously undocumented mechanism for dispersal; however, dams often eliminate suitable habitat areas downstream, suggesting that this behavior may be detrimental in riverine populations. Because larvae move during daylight hours, they also are likely to suffer mortality from trampling due to human recreational activity

Suitability of single-pass backpack electrofishing to estimate fish abundance and describe assemblage structure in prairie streams

Electrofishing is commonly used by fisheries professionals to assess fish assemblage structure and species abundance in streams. Accurate estimates of fish abundance and, consequently assemblage metrics, are typically generated with mark-recapture or maximum-likelihood depletion techniques, but doing so requires considerable sampling effort. Less intensive sampling approaches may be beneficial to fisheries managers, particularly in cases where frequent sampling of many streams is preferred. We used regression and Spearman rank-order correlation analyses to compare species catch rates and the assemblage metrics generated from single-pass electrofishing samples with multiple-pass depletion abundance estimates in Nebraska streams. We examined the influence of instream habitat features on the regression residuals to further examine the effectiveness of single-pass electrofishing. Our results suggest that single-pass electrofishing is suitable for wadeable prairie streams with relatively little habitat diversity. With few exceptions, fish species were detected and captured in similar quantities regardless of electrofishing effort, suggesting that single-pass sampling can be used to quickly assess species occurrence and relative abundance. The single- and multiple-pass electrofishing methods generated slightly different values for each assemblage metric; however, these values were not significantly different. Abundance was over- or underestimated in areas where certain species were congregated (e.g., overhanging vegetation: Red Shiner Cyprinella lutrensis, Bigmouth Shiner Notropis dorsalis, large substrates: Stonecat Noturus flavus, and darters) or difficult to sample (e.g., woody debris: Largemouth Bass Micropterus salmoides and Western Mosquitofish Gambusia affinis) using only one electrofishing pass. Single-pass electrofishing offers a reliable alternative to the more intensive multiple-pass depletion techniques; however, caution should be applied in difficult to sample areas with unique habitats

College students' knowledge of ticks in Oklahoma: Assessment and insights

Ticks (Arachnida: Acari) are common in Oklahoma and may transmit tick-borne diseases (TBDs) to people. Due to the difficulty in reducing tick populations, awareness of tick bite prevention, proper tick removal, and knowledge of when to seek medical treatment are critical. However, outreach and extension programs are hampered by a lack of knowledge of what community members know about ticks. To address this limitation, we surveyed college students enrolled in three nonmajor Entomology courses at Oklahoma State University in 2018. Of the 483 students invited to take a survey, 224 (46.4%) students took both surveys. Pre-survey responses indicated lower levels of knowledge of tick biology compared to post-survey responses. For both pre- and post-survey respondents, "ticks can jump" and "ticks reside up in trees" received the fewest correct responses. A majority of survey respondents considered Lyme disease to be the predominant TBD in Oklahoma, although it is not established in Oklahoma. Supplemental education overcame these knowledge gaps, with the exception of knowledge of Lyme disease which was still considered to be the predominant TBD in the post-survey. Our results can be used to develop assessment tools to improve extension programs and enhance protection from TBDs.Peer reviewedEntomology and Plant Patholog

Trade-Offs between Temperature and Fitness in \u3ci\u3eEuschistus heros\u3c/i\u3e (Fabricius) (Hemiptera: Pentatomidae): Implications for Mass Rearing and Field Management

The brown stink bug, Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae), is one of the most abundant soybean stink bug pests in Brazil. Temperature is a key factor that affects its development and reproduction, and fluctuating temperatures may impact the development and reproduction of E. heros differently from those under constant temperatures. The objective of this study was to evaluate the influence of constant and fluctuating temperature on the biological characteristics of E. heros in three successive generations. Treatments consisted of six constant temperatures (19oC, 22oC, 25oC, 28oC, 31oC and 34oC) and four fluctuating temperatures (25:21oC, 28:24oC, 31:27oC, and 34:30oC) evaluated for three successive generations. Second-stage nymphs were evaluated daily, and after they reached the adult stage, they were separated by sex, and the individual weight (mg) and pronotum size (mm) were recorded. After pair formation, eggs were collected to evaluate the pre-oviposition period, total number of eggs, and egg viability. The duration of the nymphal stage was reduced with an increase in both constant and fluctuating temperatures; however, at constant temperatures of 19oC, 31oC and 34oC and fluctuating temperatures of 28:24oC, there was no reproduction in adults. The base temperature and total degree day requirement for nymphal development were 15.5oC and 197.4 dd, respectively. Pre-oviposition period (d), number of eggs per female, and viability of eggs (%) were affected by temperature across the generations. The multiple decrement life table analysis revealed that mortality was highest during the molting of the secondstage nymphs. These findings have important implications for E. heros’ laboratory mass-rearing programs and for its management in fields

Hypoxia-Limited Survival, Respiration, and Mate-Guarding Behavior in the Amphipod Gammarus Pseudolimnaeus Bousfield

Survival in hypoxia, oxygen-limitation of respiration and effects of hypoxia on precopulatory mate-guarding behavior of the amphipod, Gammarus pseudolimnaeus, were tested to determine if seasonal hypoxia in Lake Taneycomo could be a limiting factor for amphipods in the lake. Currently, the Army Corps of Engineers uses oxygenation procedures at Table Rock Dam to defend 4.0 ppm dissolved oxygen (D.O.) in water entering Lake Taneycomo. However, little information exists to indicate whether this level of oxygenation is sufficient for survival, growth, and reproduction of G. pseudolimnaeus. Male, female, and juvenile amphipods survived 48 hours exposure to dissolved oxygen below the minimum daily average that is currently defended in the lake. Survival of hypoxia below 3.5 ppm was differed among genders and age with females being most sensitive, and juveniles being least sensitive. Sensitivity to hypoxia increased with an increase in temperature. Respiration of adult G. pseudolimnaeus was found to be oxygen-limited at all levels of D.O. below air saturation. Females had higher mass-specific rates of respiration and were more oxygen dependent than males at 10°C, but neither rate nor oxygen dependence of respiration differed among genders at 15 or 20°C. Hypoxia was found to inhibit mate-guarding behavior by male G. pseudolimnaeus at levels substantially above the minimum defended in Lake Taneycomo. Hypoxia limited both the male\u27s ability to regain a female when separated and the male\u27s ability to maintain mate-carrying behavior until mating could take place. It appears from the data that an increase in oxygenation procedures to defend 5 ppm instead of 4 ppm would substantially increase both respiration and mating behavior

Ecophysiology of habitat use and competition in an assemblage of salt marsh tiger beetle species

I designed six experiments to assess the physiological and ecological mechanisms that allow two sympatric species of tiger beetles (Cicindela togata and Cicindela circumpicta) to coexist in the eastern Nebraska Salt Marsh. The salt marsh is periodically flooded and I found Cicindela larvae to survive immersion and anoxia for about 6 days in typical summertime temperatures and longer at lower temperatures. I hypothesized that one mechanism of flood survival is by facultative anaerobiosis; during anoxia, larvae depress metabolic rates and conduct anaerobic metabolism. Compared with larvae of Amblycheila cylindriformis (a tiger beetle species whose habitat is never flooded), C. togata survived longer, depressed metabolism further, and utilized different anaerobic pathways during the first 24 hours of anoxia. Beyond seasonal flooding, tiger beetle larvae (sedentary predators) face prolonged starvation compared to adults (active foragers). I hypothesized that during periods of starvation, adult and larval tiger beetles use fat body reserves differently because of differing foraging strategies. Whole body triacylglycerol and phospholipid compositions differed between fed and starved beetles. To test niche differentiation, I investigated the influences of soil salinity and shade on oviposition choices by females of the two tiger beetle species. I found resource use consistent with niche partitioning. I also quantified potential prey availability by placing sticky traps in exposed and shaded areas of the salt flat; the captures were dominated by Dolichopodidae and Cicindelidae. Finally, I conducted a series of experiments to document niche shifts and intraguild predation by C. circumpicta on C. togata. Cicindela togata serves as intraguild prey for C. circumpicta. Behaviorally, C. togata uses different microhabitats and shifts its foraging behavior, taking longer to feed in the presence of C. circumpicta. The biological significance of these findings lies in an appreciation of the physical and ecological community of predators that share a relatively harsh and food-limited habitat

The Only Good Mosquito Is a Dead Mosquito: Student-Led Scientific Investigations of Mosquito Predation

Most everyone loves to hate mosquitoes. The exercise begins by asking students to describe mosquitoes and what would happened if mosquitoes were eliminated. Then we do a hands-on demonstration of mosquito larvae being eaten by a dragonfly larva. Next, we have students design experiments to see how many mosquito larvae are consumed by other invertebrates (in this case dragonfly larvae and tadpole shrimp). Both of these predator groups readily eat mosquito larvae in a classroom setting and so students get to witness “the wild kingdom” first hand and then interpret their hypotheses. Then, we circle back to what good are mosquitoes… without them, lots of other organisms that we know and like would be food-limited. We have used this open-ended investigation with majors and non-majors and found it to be a great technique to improve science literacy while making it fun to observe mosquito larvae being eaten

A Synopsis of Nebraska Grasshopper Distributions

Between 2005 and 2007, 656 new county records and eight new state records were obtained for Nebraska’s short-horned grasshoppers (Acrididae and Romaleidae). This represents an increase of 30% in the known grasshopper county records in Nebraska. Based on the large number of new distribution records, it appears that the previous distributions of Nebraska’s grasshoppers greatly underestimated the actual distributions. The new grasshopper state records were: Boopedon gracile, Chloealtis abdominalis, Encoptolophus subgracilis, Melanoplus bispinosus, Melanoplus borealis, Melanoplus punctulatus, Paratylotropidia brunneri, and Psinidia fenestralis were obtained. These new records will aid in both grasshopper monitoring for pest outbreaks and in conservation of rare and declining species which are often habitat specialists associated with prairie ecosystems