Habitat quality, and the levels of habitat variables that are associated with good habitat, can vary between years. Therefore, animals that are able to adjust their habitat selectivity should enjoy ...higher fitness. I examined the use of experience in habitat selection during natal dispersal in
Hemilepistus reaumuri, a monogamous, semelparous desert isopod. Young from the previous year emerge in the spring and walk from a few to over one thousand metres before establishing burrows or settling in already established burrows. Isopods were held in outdoor pens for 7-day priming treatments, then moved to new pens and tested for settling 4 days later. Perceived habitat quality was defined as the fraction of isopods settling in each pen during its use in the 7-day priming treatments. Settling was tested as a function of the change in perceived quality isopods experienced. Settling was significantly positively correlated with change in perceived quality, suggesting that experience is used to prime habitat selection during dispersal, and that the effects of experience last at least a few days in desert isopods. Time of year also had a significant positive effect on settling. The effect of change in perceived quality was stronger than the effect of perceived quality in the final pen. If changes in habitat are used to calibrate settling decisions, longer dispersal distances may be needed to allow for habitats to be compared. Use of experience to regulate settling may also affect the population dispersal response to habitat change.
Needs to improve educational access for women in the Global South have been well documented throughout the literature. The need and impact of non-governmental organizations for food security ...improvement, educational access, and community sustainability work in the Global South has been heightened since the pandemic. Our study focused on several sustainable development goals (SDGs) where we utilized experiential learning and the Targeting Outcomes of Programs (TOP) model to assess participants’ needs in developing, implementing, and evaluating the adoption of food and agricultural sciences curricula. We utilized a case study method and semi-structured interviews with primary stakeholder groups to answer each research objective. Most participants had increased confidence in growing food for their families due to the knowledge they gained and the practices they learned by participating in the food and agricultural sciences curricula. TOP indicators aligned with reducing hunger and improving sustainable agriculture are identified in SDG 2. Data regarding knowledge, attitudes, skills, and aspirations revealed that participants wanted to pursue careers in agriculture due to the food security and financial advantages the industry offered. Program graduates indicated their desire for food and agricultural sciences curricula to be provided more to improve girls’ self-independence, as well as to address the feasibility and entrepreneurial solutions to reduce poverty, promote learning, and increase community sustainability and vitality.
Reduced fitness among resistant versus susceptible individuals slows resistance evolution and makes it easier to manage. A loss of resistance costs could indicate novel adaptations or mutations ...contributing to resistance. We measured costs of resistance to imidacloprid in a Massachusetts resistant population compared with a Massachusetts susceptible population in 1999 in terms of fecundity, hatching success, egg development time, and sprint speed. Resistance was additive and seemed to be polygenic with high heritability. The fecundity cost appeared overdominant in 1999, and the hatch rate cost was partly recessive in 1999, but neither was significantly different from dominant or recessive. In 2004, we repeated our measures of resistance costs in Massachusetts in terms of fecundity and hatching success, and we added a new resistant population from Maine. In 2005, we compared development time of Maine resistant and the laboratory susceptible colony eggs. Significant fecundity costs of resistance were found in both population in both 1999 and 2004, and significant egg developmental time costs were found in 1999 and 2005. However, the hatching success costs of resistance were significant in 1999 and not apparent in 2004, suggesting some modification or replacement of the resistance genes in the intervening time.
The Colorado potato beetle,
Leptinotarsa decemlineata
(Say), is widely regarded as the most important insect defoliator of potatoes. Its current range covers about 16 million km
2
in North America, ...Europe, and Asia and continues to expand. This insect has a complicated and diverse life history, which is well-suited to agricultural environments, and makes it a complex and challenging pest to control. Dispersal, closely connected with diapause, feeding, and reproduction, allow the Colorado potato beetle to employ “bet-hedging” reproductive strategies, distributing its offspring in both space (within and between fields) and time (within and between years). The Colorado potato beetle played a large role in creating the modern pesticide industry, with hundreds of chemicals tested against it. High selection pressure, together with natural propensity to adapt to toxic substances, eventually resulted in a large number of insecticide-resistant Colorado potato beetle populations. Since the middle of the last century, the beetle has developed resistance to 52 different compounds belonging to all major insecticide classes. Resistance levels vary greatly among different populations and between beetle life stages, but in some cases can be very high (up to 2,000-fold). Known mechanisms of Colorado potato beetle resistance to insecticides include enhanced metabolism involving esterases, carboxylesterases and monooxygenases, and target site insensitivity, as well as reduced insecticide penetration and increased excretion. There is also some evidence of behavioral resistance. Resistance mechanisms are sometimes highly diverse even within a relatively narrow geographical area. Resistance is usually inherited as an incompletely dominant or incompletely recessive trait, with one or several genes involved in its determination. Because of pleiotropic effects of resistant alleles, insecticide-resistant beetles often have reduced relative fitness in the absence of insecticides. Rotating different classes of insecticides and reducing insecticidal pressure on pest populations by provision of temporal and spatial refuges from exposure to toxins have been proposed to delay evolution of resistance. However, insecticide resistance in this insect will likely remain a major challenge to the pest control practitioners. Still limited understanding of beetle biology, its flexible life history, and grower reluctance to adopt some of the resistance management techniques create impediments to successful resistance management. Overcoming these obstacles is not an easy task, but it will be crucial for sustainable potato production.
Differences in the emergence, movement, and settling patterns of individuals during natal dispersal can provide testable hypotheses about the costs and functions of movement. Emergence, movement, and ...settling patterns were studied in desert isopods, Hemilepistus reaumuri. The young of this semelparous, monogamous, crustacean emerge from their natal burrows each spring and search for sites to establish new burrows or gain acceptance as mates in occupied burrows. Dispersal was measured in a long, narrow corridor into which individuals marked after emergence were monitored. Females emerged slightly earlier than males with substantial overlap. Size or condition varied with time before settling differently in males and females. Isopods in good or poor condition did not differ in distance traveled, but males in good condition took more time before settling. Small males were more likely to start new burrows and took less time before settling, suggesting they might be acting in anticipation of losing contests for female-initiated burrows. Larger females and those in higher condition were more likely to start new burrows and took less time before settling. The pattern in females could reflect male choice or constraints or costs associated with burrow establishment in females, which should be tested. Measures of dispersal based on recaptures of traveling or recently settled individuals may differ from the distribution of successful reproduction. In this study travelers were observed at shorter average distances than settlers, but successful settlers traveled less far than unsuccessful ones.PUBLICATION ABSTRACT
1 Resistance to insecticides is a model system for studying adaptation. Although selection for resistance is always strong in areas and seasons where populations are exposed to insecticides, costs of ...resistance, which may only be expressed in the absence of insecticide use, will shape how quickly resistance will evolve. 2 We used sperm precedence to measure the shifts in resistance to imidacloprid in a natural population during winter diapause in the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). Because adult beetles overwinter with viable autumn sperm, but sperm from spring matings take precedence over stored sperm, we used the difference in resistance of springmated and autumn-mated overwintered females to estimate the shift in resistance during the winter. Offspring of autumn-mated females were 2.7- or 2.5-fold more resistant compared with offspring from spring-mated females in two replicate trials. 3 We also measured the resistance of late summer and spring emergent adults in fields treated and untreated with imidacloprid in the first year. Adults from the treated field were 13.7-fold more resistant and adults from the untreated field were 2.6-fold more resistant compared with the next spring's emergers. 4 These large costs of resistance observed in the field and inferred from resistance declines during diapause help to explain the observation that imidacloprid resistance has increased only slowly over the decade of widespread use against this species, and how insecticide resistance in general can cycle annually.
Discontinuous wildlife reserves can lead to inbreeding depression for fragmented populations of threatened species. To offset such effects, conservation managers frequently turn to translocation ...strategies, such as the one-migrant-per-generation rule (OMPG), which relies on many unrealistic assumptions of Wright's (1931) island model. We therefore propose an alternate translocation approach based on the natural dispersal rates of focal species, using two endangered Hawaiian tree snails species, Achatinella sowerbyana and A. mustelina, as practical examples. The rate at which tree snails historically dispersed across reserve boundaries can be used to guide contemporary translocation across those dispersal barriers. Snail movements were monitored for three years using capture-mark-recapture (CMR) methods, and analyzed with a multi-strata model in program MARK to obtain survival and dispersal rates. We tested and ranked models, including age, time, weather, and location effects on survival, dispersal, and capture probabilities. Annual mortality ranged from over 50% to less than 20%, by site, mirroring expectations from anecdotal observations of predator abundances. Monthly dispersal rates between isolated tree clusters were recorded between 3% and 24% of a population, depending on the population's exposure to severe weather rather than its species designation. Simulations based on dispersal-distance distributions were then applied to estimate emigration rates beyond the finite study sites. Emigration rates ranged among sites from 0.7% to 6.7% of the population per month, translating to between 6 and > 100 emigrants per year, depending on the density of snails at each site and the site's dimensions. The site boundaries are directly analogous to current and future reserve designs, and we show how such emigration rates can be used to guide two-way translocation rates across such artificial barriers.
Single crystals of Ba2Nb3S8I have been grown using iodine-vapor transport in fused-quartz tubes. The crystals form as flakes with typical areas of 5–10 mm2 and thicknesses of 5–11 μm. The crystal ...structure was determined using single-crystal x-ray diffraction with the aid of an APEX II CCD diffractometer. The structure shows trigonal symmetry with space group P31c and lattice parameters a = b = 10.0156(5) Å and c = 25.1414(15) Å. Compositional analysis via x-ray spectroscopy confirms the presence of iodine. Superlattice reflections are evident in x-ray precession images. Measurements of the electrical resistivity reveal a metallic temperature dependence and superconductivity near 1 K. Polycrystalline samples of Ba2Nb3S8I were made in order to have samples large enough for other bulk physical properties measurements. Magnetic susceptibility reveals antiferromagnetism below 275 K. The coexistence of antiferromagnetism and superconductivity is surprising. Specific heat measurements reveal the electronic coefficient γ = 3.95(66) mJ/mol K2. The jump in the specific heat at the superconducting transition temperature Tc (ΔC/γTc = 1.4(2)) and the energy gap associated with the superconducting state (Eg = 0.405(17) meV) agree well with BCS theory.
•The new compound Ba2Nb3S8I and its crystal structure is reported.•Single crystal growth and growth of bulk polycrystals are reported.•Ba2Nb3S8I is a superconductor, with a Tc near 1 K.•A wide range of physical properties were measured including: electrical resistivity, hall coefficient, magnetic susceptibility, critical magnetic field, and heat capacity.
