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The army cutworm, Euxoa auxiliaris (Grote), is a migratory noctuid that is both an agricultural pest and an important late-season food source for grizzly bears, Ursus arctos horribilis (Linnaeus, Carnivora: Ursidae), within the Greater Yellowstone Ecosystem. Beyond the confirmation of the moths' seasonal, elevational migration in the mid-1900s, little else has been documented about their migratory patterns. To address this missing ecological component, we examined (1) migratory routes during their spring and fall migratory periods throughout their natal range, the Great Plains, and (2) natal origin at two of their summering ranges using stable hydrogen (δ 2H) analyses of wings from samples collected within the areas of interest. Stable carbon (δ 13C) and stable nitrogen (δ 15N) analyses of wings were used to evaluate larval feeding habits of the migrants and agricultural intensity of natal origin sites, respectively. Results suggest that, rather than migrating exclusively east to west, army cutworm moths are also migrating north to south during their spring migration. Moths did not exhibit natal origin site fidelity when returning to the Great Plains. Migrants collected from the Absaroka Range had the highest probability of natal origin in Alberta, British Columbia, Saskatchewan, the most southern region of the Northwest Territories, and second highest probability of origin in Montana, Wyoming, and Idaho. Migrants collected in the Lewis Range had the highest probability of origin in the same provinces of Canada. Results suggest that migrants of the Absaroka Range fed exclusively on C3 plants as larvae and rarely fed in heavily fertilized agroecosystems. [ABSTRACT FROM AUTHOR]

Pantala flavescens (Fabricius 1798) (Odonata: Libellulidae) is one of the most common species of migratory dragonflies. P. flavescens adults were captured by a searchlight trap on Beihuang Island (BH Island; 38°24'N, 120°55'E) from 2003 to 2016, where there is no freshwater. This inspired our research to analyze the pattern of seasonal migration and population dynamics. Stable hydrogen isotope measurement and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) were used to simulate the migration pathway of P. flavescens between different breeding habitats. The results showed that there was no significant difference among population numbers of this overseas migration across years (F13, 2161 = 0.85, P = 0.604); however, the numbers were significantly different across months (F5, 2161 = 3.91, P = 0.003). Our geospatial natal assignment model suggested that P. flavescens trapped on BH were originated in different geographical regions and might have three movement strategies: wandering around northern China and north-bound (positive) and south-bound (negative) movements. Among them, the majority were engaged in wandering around northern China. Model simulations suggested that P. flavescens toured around BH. The results contribute to the knowledge of P. flavescens population ecology in a large-scale geographic region and will aid in the prediction and interpretation of insect migration patterns in response to climate change. [ABSTRACT FROM AUTHOR]

From a regulatory perspective, Asian gypsy moth is a species complex consisting of three species of Lymantria and two subspecies of Lymantria dispar (L.), differing from the European subspecies, L. dispar dispar (L.), by having consistently flight-capable females. As such, the invasion potential in North America is thought to exceed that of European gypsy moth. USDA-APHIS therefore has a monitoring program to detect Asian gypsy moth at highrisk introduction pathways. Molecular markers are used to improve the diagnosis of Asian gypsy moth. One such marker, which targets the FS1 locus, detects an allele, FS1-A, prevalent in Asian populations but occurring at low frequencies (3-6%) throughout the European gypsy moth's range in North America. However, some locales, such as Minnesota, exhibit elevated FS1-A frequencies. We studied the distribution of the FS1-A allele in northern Minnesota, 2013-2014, assessing spatial patterns in the distribution of the FS1-A allele using Moran's I and using spatial regression techniques to examine if the FS1-A allele was associated with putative movement pathways. We also used time series analysis to discern if temporal patterns in FS1-A or possible introduction events occurred. Our results indicated that FS1-A occurred randomly in space and time. We found no evidence that elevated FS1-A frequencies were associated with movement pathways or possible immigration events into this region over the two years. Elevated frequencies of the FS1-A allele within this region could be due to genetic drift and allelic surfing along the expanding population front, or to selection of physiological or behavioral traits. [ABSTRACT FROM AUTHOR]

Adaptation to different host plants can lead to host-associated differentiation (HAD). The mites Oligonychus perseae and Oligonychus punicae have a broad range of host plants, but, to date, records of them coexisting sympatrically had only been reported on avocado. However, our field observations showed both species coexisting on host plants other than avocado. The lack of previous records of these mites on the host plants studied here suggests only recent divergence to new host plant species. Previous studies showed that O. punicae had a limited migration capacity compared with O. perseae, suggesting that O. punicae is more likely to develop a close host plant relationship leading to HAD. Adults of both species were collected from trees hosting both mite species. Three genera of host plants considered were Persea, Salix, and Alnus; two species within one genus were Alnus jorullensis and Alnus acuminata; and three varieties within one species were Persea americana var. Fuerte, var. Hass, and var. Criollo, a noncommercial variety. Using sequence data from a segment of the mitochondrial cytochrome oxidase subunit I, the phylogenetic relationships and genetic population structure of both mite species in relation to the host plant were determined. Oligonychus perseae populations showed a significant population structure in relation to host plant at the species and genus level, but there was no effect of variety. In contrast, host plant explained none of the genetic variation among O. punicae populations. The potential role of coexistence mechanisms in the contrasting genetic population structure of both mite species is discussed. [ABSTRACT FROM AUTHOR]

In Wisconsin, vegetable crops are threatened annually by infection of the aster yellows phytoplasma (AYp), the causal agent of aster yellows (AY) disease, vectored by the aster leafhopper, Macrosteles quadrilineatus Forbes. Aster leafhopper abundance and infectivity are influenced by processes operating across different temporal and spatial scales. We applied a multilevel modeling approach to partition variance in multifield, multiyear, pest scouting data sets containing temporal and spatial covariates associated with aster leafhopper abundance and infectivity. Our intent was to evaluate the relative importance of temporal and spatial covariates to infer the relevant scale at which ecological processes are driving AY epidemics and identify periods of elevated risk for AYp spread. The relative amount of aster leafhopper variability among and within years (39%) exceeded estimates of variation among farm locations and fields (7%). Similarly, time covariates explained the largest amount of variation of aster leafhopper infectivity (50%). Leafhopper abundance has been decreasing since 2001 and reached its minimum in 2010. The average seasonal pattern indicated that periods of above average abundance occurred between 11 June and 1 August. Annual infectivity appears to oscillate around an average value of 2% and seasonal periods of above average infectivity occur between 19 May and 15 July. The coincidence of the expected periods of high leafhopper abundance and infectivity increases our knowledge of when the insect moves into susceptible crop fields and when it spreads the pathogen to susceptible crops, representing a seasonal interval during which management of the insect can be focused. [ABSTRACT FROM AUTHOR]

Each year the Mythimna separate (Walker), undertakes a seasonal, long-distance, multigeneration roundtrip migration between southern and northern China, Despite its regularity, the decision to migrate is facultative, and is controlled by environmental, physiological, hormonal, genetic, and molecular factors. Migrants take off on days 1 or 2 after eclosion, although the preoviposition period lasts ≈7 d. The trade-offs among the competing physiological demands of migration and reproduction are coordinated in M. separata by the "oogenesis-flight syndrome," Larvae that experience temperatures above or below certain thresholds accompanied by appropriate humidity, short photoperiod, poor nutrition, and moderate density tend to develop into migrants. However, there is a short window of sensitivity within 24 h after adult eclosion when migrants can be induced to switch to reproductive residents if they encounter extreme environmental factors including starvation, low temperature and long photoperiod. Juvenile hormone ( JH) titer is low before migration but high titers are associated with termination of migratory behavior and the switch to reproduction. Early release of JH by the corpora allata in environmentally stressed 1-d old adults, otherwise destined by larval conditions to be migrants, switches them to residents. Offspring inherit parental additive genetic effects governing migratory behavior. However, they also retain flexibility in expression of both flight and reproductive life history traits. The insect neuropeptide, allatotropin, which activates corpora allata to synthesize JH, controls adult flight and reproduction. Future research directions to better understand regulation of migration in this species are discussed. [ABSTRACT FROM AUTHOR]

Edge effect tests have been used in a number of studies on obliquebanded leafroller, Choristoneura rosaceana (Harris), to test for evidence of mated female immigration into pheromone- treated orchards. This type of test compares obliquebanded leafroller presence or activity around the perimeter of an orchard against presence or activity in the interior. Higher numbers detected around the edges of an orchard would indicate higher levels of flight activity at the edge, a pattern that could be generated by high levels of immigration. Recent work has shown that the spatial distribution of recaptured obliquebanded leafroller adults released from a single location can be directionally biased, which could obscure the ability to detect an edge effect. To test this theory, data from an orchard study conducted in 1991 that found no significant edge effect was reanalyzed. When we accounted for the directional bias in the distribution of first-generation mated female moths, we found an edge effect with significantly more mated females captured in the edge traps than in the center or mid-interior traps. No edge effect was found when the directional bias was ignored. In addition, second-generation males and mated females both showed a significant edge effect that had not been detected in the original analysis, which had combined both first- and second-generation data. [ABSTRACT FROM AUTHOR]

The high-altitude wind-borne migration of beet webworm, Loxostege sticticalis, moths with other insects and their short-distance dispersal were observed with a digital scanning radar and twin light-traps (a vertical-pointing searchlight trap operated alongside a ground-based conventional light-trap) in northern China in 2002. Catches in both light traps suggested there were four flight periods of L. sticticalis during our study. The ovarian development stage of females caught in the light traps coupled with radar observations indicated that L. sticticalls migrated to the northeast in early June, whereas locally bred moths dispersed over shorter distances in mid-July and early August. The variation of the area density of insects through time during the spring migration was different from that during the summer dispersal; there was no density peak during spring, but such a peak occurred every evening in summer. Collective orientation by the moths was observed in the spring migration, with the direction of orientation being toward the northeast. In contrast, there was no common orientation in summer. Multilevel layering of migrants was seen every night in our observations in both spring and summer. The layering phenomenon was related to wind speed maxima rather than to temperature inversions when the air temperature was above the threshold for migration. [ABSTRACT FROM AUTHOR]

An understanding of boll weevil (Anthonomus grandis Boheman) dispersal behavior is essential to characterizing and responding to the threat of migration into eradication zones. Genetic variation in boll weevil mitochondrial DNA (mtDNA) was sampled and analyzed to make inferences on the magnitude and geographic pattern of genetic differentiation among weevil populations from 20 locations across eight U.S. states and northeast Mexico. Polymerase chain reaction (PCR)-restriction fragment length polymorphisms (RFLPs) analysis was conducted on a 12.4-kb amplicon of mtDNA from each of 419 individuals. A total of 28 distinct mtDNA haplotypes, 17 of which were unique to single locations, were identified from restriction reactions of 10 informative endonucleases. Haplotype and nucleotide diversity was generally greater in southern than northern populations and was greater in the east than the west among northern populations. Genetic differentiation between eastern and western populations was pronounced, and phylogenetic analyses revealed two major clades corresponding to these regions. These results are consistent with historical boll weevil range expansion into the southeastern United States from Mexico and a secondary colonization of the High Plains. Evidence suggests that gene flow is limited between eastern and western populations but is relatively high among populations within the eastern region. In addition, estimates of gene flow indicate that migration between locations separated by <300 km is frequent. [ABSTRACT FROM AUTHOR]

Paired suction traps were used to study the habitat choice of migrating aphids in adjacent crop and natural habitats in east central Illinois. Traps were placed in a row-crop field and a restored prairie for 4 yr at one site, and a row-crop field and a wooded plot for 3 yr at another. Row crops were corn or soybean, rotated annually. We did not wish to sample aphids that were native to the local habitats because they would be in a habitat by circumstance of birth, and not necessarily by choice. We therefore removed from the habitat choice analysis any aphid species that colonize plants in either the agricultural or natural habitat. Numbers of aphids from outside sources in the two adjacent habitats were compared. In 2 of 4 yr, outside-source aphids were more abundant in the row-crop than the restored prairie, despite the absence of potential host plants in both habitats. In all 3 yr, outside-source aphids were trapped in greater numbers in the crop than in the woods. Selection of the crop over the natural habitat occurred during almost all sampling periods throughout the summers. We present possible explanations for the aphids' apparent preference for crop habitats and provide brief discussions of abundant aphids, local--as well as outside--source species, trapped in our study. We also discuss the relevance of our study to the understanding of long- and short-distance aphid migration and aphid vectoring of plant pathogens. [ABSTRACT FROM AUTHOR]

We compared the effect of intercropping on oviposition and emigration behavior of two related specialist moth species. The effect of height of the intercrop species (red clover) on oviposition was studied in field cages, using the leek moth, a specialist on Allium species, and the diamondback moth, a specialist on Brassica species. The moths were also evaluated in an open field experiment. Emigration of both moths was studied in the laboratory and in the field in cages with host plants, red clover (nonhost), host plant and red clover, and bare soil. The possible influence of noncontact stimuli was also studied in the laboratory. The leek moth laid the same amount of eggs in monoculture as in intercroppings with high and low clover. White cabbage intercropped with high clover received fewer eggs of the diamondback moth compared with a cabbage monoculture. Intercropping with low clover did not reduce the amount of eggs laid. Intercropping did not appear to affect the emigration of either the leek moth or the diamondback moth. Leek moths were less likely to emigrate than diamondback moths during the first 4 h of the study. We conclude that diamondback moth may be more likely to be controlled by intercropping than leek moths. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that changes in photoperiod alone are responsible for the delay in the onset of sexual maturity that has been previously observed in natural populations of the migratory black cutworm, Agrotis ipsilon (Hufnagel), moth. We hypothesized that under short days, which occur at the onset of the spring and fall migrations, the first age at which males and females engage in sexual communication would be later than under long days typical of nonmigratory periods. Individuals were kept at 25°C from egg to adult under three photoregimes that they encounter in nature at different latitudes: 12:12 (L:D) h (late March and late September), 14:10 (L:D) h, and 16:8 (L:D) h. As predicted, the mean age at which females first called (i. e., released pheromone) was earlier under long-day than under short-day photoregimes, but this trend was not significant. The percentage of females that called over a 6-d-period was similar among photoregimes but it varied with age. There was no interaction between photoperiod and age on the percentage of females calling. Pheromone production, measured as the quantity of Z7-12:Ac in pheromone gland extracts, was lower under long-day than under short-day photoregimes. On average, 1-d-old females produced less pheromone than older females. Photoperiod and age showed a significant interaction in their effect on the quantity of Z7-12:Ac, but not in the direction predicted by our hypothesis. Males reared under short days showed higher percentages of response than did males reared under long days. Age had a significant effect on male response but it was independent from the effect of photoperiod. We conclude that although photoperiod length can influence calling, pheromone production, and male response, it has little effect on the age at which A. ipsilon reach sexual maturity. Changes in photoperiod alone cannot explain the delayed maturity observed in the field. Other factors, alone or in combination with photoperiod, may be necessary to induce the reproductive diapause that A. ipsilon undergoes in its fall migration. [ABSTRACT FROM AUTHOR]