BioOne.org will be down briefly for maintenance on 14 May 2025 between 18:00-22:00 Pacific Time US. We apologize for any inconvenience.
Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact helpdesk@bioone.org with any questions.
The expansion of urban areas is occurring globally, but not all city neighborhoods are gaining population. Because of economic decline and the recent foreclosure crisis, many U.S. cities are demolishing abandoned residential structures to create parcels of vacant land. In some cities, weak housing markets have, or will likely, recover in the near term, and these parcels will be redeveloped. However, in other cities, large numbers of abandoned parcels have no significant market value and no likelihood of near-term redevelopment. The creation of these vacated green spaces could offer opportunities to preserve declining species, restore ecosystem functions, and support diverse ecosystem services. Arthropods are an important indicator of the ability of urban vacant land to serve multiple functions, from conservation to food production. Across Europe, vacant lands have been found to support a diversity of rare species, and similar examinations of arthropods within this habitat are underway in the United States. In addition, using vacant land as a resource for local food production is growing rapidly worldwide. Arthropods play key roles in the sustainability of food production in cities, and land conversion to farming has been found to influence their community composition and function. A greater focus on quantifying the current ecological value of vacant land and further assessment of how changes in its ecosystem management affect biodiversity and ecosystem processes is clearly needed. Herein, we specifically focus on the role of arthropods in addressing these priorities to advance our ecological understanding of the functional role of vacant land habitats in cities.
The aphelinid parasitoid Eretmocerus hayati Zolnerowich & Rose (Hymenoptera: Aphelinidae) was recently released in Australia as a biocontrol agent against the crop pest Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae). It was found that the parasitoid can spread over several kilometers in asingle generation and continue laying eggs for over afortnight. A simple wind-advection model was fitted to emergence data from a first release between Fassifern and Kalbar, Queensland, and its predictive ability was tested against the second release near Carnarvon, Western Australia. The fitting of the model was used to develop several hypotheses about the dispersal of E. hayati, which were validated by the second release: E. hayati flies in the same direction as the wind to a distance proportional to the wind speed; this wind-borne flight takes place at any time during daylight hours; a flight is attempted every day after emergence unless there are high wind conditions during that day; and the high wind condition that will delay flight is wind speeds in excess of ≈2 m/s. This model of E. hayati dispersal may be contrasted with previous models fitted for Eretmocerus species, for which dispersal was dominated by diffusion processes, and parasitoid spread was constrained to the scales of tens and hundreds of meters.
Cloeon dipterum (L.) (Ephemeroptera: Baetidae), the common wetland mayfly, emerges and oviposits every season, except winter, and has overlapping generations in the temperate region. We investigated the life history of C. dipterum associated with drought. Field experiments and sampling were conducted in a wetland (25 by 80 m) located in central Korea. Larvae were sampled weekly within two habitat types (a large, deep wetland and a small, shallow wetland) using a dredge sampler, and adults were sampled every 2 d with cube emergence traps, from July 2011 to September 2012 (except winter). C. dipterum had an extended emergence period from late April to early October with four peaks: early May, mid-June, July, and August/September. When the water depth was shallow because of drought, emergence was suppressed and delayed. The accumulated degree-days and body length of the overwintering cohort that emerged in spring 2012 were markedly larger and longer than those of other cohorts. Adults emerged intensively around sunset. C. dipterum has a multivoltine life cycle with four cohorts per year; its life history and population density can be changed by natural disturbances such as drought and fish predation.
Leishmania infantum—the causal agent of human and canine leishmaniasis in the Mediterranean basin-remains the most important of the phlebotomine sand fly-borne pathogens in the area. However, information on phlebotomine sand flies in certain European regions remains scarce and consequently epidemiological modeling, risk prediction, and disease control are difficult. Thus, we aimed to investigate the presence and distribution of phlebotomine sand fly vectors of L. infantum in an endemic region of continental Mediterranean Spain. Climatically stratified trapping of phlebotomine sand flies was performed over 39 points in south- central Spain. Later on, the effect of ecogeographical variables—geography trend, climate, habitat, and hosts—over the abundance of the predominant species—Phlebotomus perniciosus Newstead, 1911—was analyzed. Polymerase chain reaction was performed over pools of the captured species to search for L. infantum DNA. There were 152 phlebotomine sand flies (142 Ph. perniciosus and 10 Phlebotomus ariasi Tonnoir, 1921) captured. Model results showed that Ph. perniciosus abundance is expected to be higher in warm agricultural areas within the study region in agreement to previous findings in other climatic regions. Molecular analyses revealed the presence of L. infantum DNA in pools from locations in the study region displaying the highest abundance of phlebotomine sand flies. These findings suggest that along mainland Spain, warm agricultural landscapes are more prone to harbor higher abundances of Ph. perniciosus and account for a higher risk of exposure to L. infantum.
We conducted abroad geographic survey in the northwestern United States to quantify production losses in the alfalfa leafcutting bee (Megachile rotundata (F.), Hymenoptera: Megachilidae) , a solitary pollinator used extensively in alfalfa seed production. Viable larvae were found in only 47.1% of the nest cells collected at the end of the season. Most of the rest of the cells contained pollen balls (typified by a provision but no larva; 16.7%), unknown causes of mortality (15.5%), or larvae killed by chalkbrood (8.0%). Prevalence of pollen balls was correlated positively with bee release rates and negatively with alfalfa stand age. The unknown mortality was correlated with the U.S. Department of Agriculture-Plant Hardiness Zone, and thus, some of the mortality may be caused by high temperature extremes, although the nesting season degree-days were not correlated with this mortality. Chalk-brood prevalence was correlated with possible nesting-resource or crowding-related factors, such as the number of bees released per hectare and the number of shelters used, but not with nesting board disinfection practices. Vapona is used to control parasitoids when the parent bees are incubated before release, and use of this fumigant was associated with an increase in both chalkbrood and diapausing offspring, although any reason for these correlations are unknown. This survey quantifies the variation in the quality of alfalfa leafcutting bee cocoons produced across much of the U.S. alfalfa seed production area.
Sitobion avenae (F. ) is a cosmopolitan cereal pest, but geographic barriers like the Qinling Mountains in the Shaanxi Province of China may lead to isolation among its populations, thus causing allopatric speciation. We sampled S. avenae populations from areas north (mean annual temperature, ≈9°C) and south (mean annual temperature, ≈14°C) of the Qinling Mountains, and tested them at 20°C in common garden experiments. The results showed that northern populations had reduced developmental time for first-instar nymphs but prolonged for third- and fourth-instar nymphs compared with southern populations. The postreproductive time and total lifespan of adults from southern populations were longer than those from northern populations, but no significant differences were found in reproductive time or age at first reproduction. Southern populations showed higher lifetime and daily fecundities than northern ones. Significant differences were found in correlation of life-history traits between northern and southern populations. Principal component analyses (PCAs) of S. avenae's vital life-history traits showed separation of populations from three southern locations, indicating their local adaptation. The clustering patterns generated by PCA also showed divergence between northern and southern populations. Alatae of S. avenae seemed to be able to disperse across the Qinling Mountains, which was indicated by the clustering together of some individuals from one side of the mountains with those from the other side. The impacts of the Qinling Mountains on the divergence and gene flow among S. avenae populations, as well as the potential of allopatric speciation for this species, are discussed.
Euschistus servus (Say) can develop a generation on wheat, Triticum aestivum L., before moving to corn, Zea mays L., where it can be a pest. Because effective management methods are unknown, this study sought to describe the spatial distribution and dispersal of E. servus in the wheat and corn interface. In addition, Oebalus pugnax (F.) densities were documented in both crops. Wheat fields adjacent to the corn were sampled before harvest and stink bugs were marked using a product containing egg whites. Dispersal into the adjacent corn was measured using grid sampling, and dispersion was measured over time using an immunoassay targeting egg albumin on E. servus collected in corn. Dispersion was measured using Anselin Local Moran's I for unmarked stink bugs only. O. pugnax was prominent in wheat but was rarely recovered from corn. In contrast, E. servus was common in wheat during both years and dispersed into the adjacent corn. E. servus nymph and adult densities increased quadratically over time in corn in 2011. In contrast, E. servus nymph densities decreased over time in corn in 2012, while adult densities remained static. Most aggregations of E. servus nymphs and adults were located on the edge of the corn, directly adjacent to the harvested wheat. This is likely the first study to directly document the movement of E. servus nymphs to the adjacent crop. Movement from wheat to corn was not consistent between the years and may have been influenced by factors such as variations in weather, timing of wheat harvest, or other available alternative hosts.
Competition for food, mates, and space among different individuals of the same insect species can affect density-dependent regulation of insect abundance or population dynamics. The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious invasive pest of North American ash (Fraxinus spp.) trees, with its larvae feeding in serpentine galleries between the interface of sapwood and phloem tissues of ash trees. Using artificial infestation of freshly cut logs of green ash (Fraxinus pennsylvanica Marshall) and tropical ash (Fraxinus uhdei [Wenzig] Lingelsh) with a series of egg densities, we evaluated the mechanism and outcome of intraspecific competition in larvae of A. planipennis in relation to larval density and host plant species. Results from our study showed that as the egg densities on each log (1.5–6.5cmin diameter and 22–25cmin length) increased from 200 to 1,600 eggs per square meter of surface area, larval survivorship declined from ≈68 to 10% for the green ash logs, and 86 to 55% for tropical ash logs. Accordingly, larval mortality resulting from cannibalism, starvation, or both, significantly increased as egg density increased, and the biomass of surviving larvae significantly decreased on both ash species. When larval density was adjusted to the same level, however, larval mortality from intraspecific competition was significantly higher and mean biomasses of surviving larvae was significantly lower in green ash than in tropical ash. The role of intraspecific competition of A. planipennis larvae in density-dependent regulation of its natural population dynamics is discussed.
Numerous bee species provide pollination services in agricultural ecosystems. Evaluating a pollinator's performance with regard to a crop is an important step in attributing pollination services and predicting how changes in a bee community or foraging environment will affect those services. We used multiple criteria to evaluate pollinators of North Carolina highbush blueberry, Vaccinium corymbosum L., agroecosystems. For five groups of bees (Apis mellifera L., Bombus spp., Habropoda laboriosa F., small native bees, and Xylocopa virginica L.), we measured forager abundance through transect observations, quantified per-visit efficiency as viable seed set resulting from a single visit, and analyzed bee presence in different weather conditions.Wealso considered two other criteria affecting pollinator performance—visitation rate and interspecific influence. A. mellifera was the most abundant bee in the majority of our survey sites, yet had low per-visit efficiency and reduced foraging activity in inclement weather. Small native bees were highly efficient pollinators. Their visits resulted in nearly twice as many seeds as A. mellifera or H. laboriosa. Bombus spp., H. laboriosa, and small native bees were more resilient to fluctuations in temperature, wind speed, and solar radiation than A. mellifera. Although nectar-robbing X. virginica contributed to little pollination through direct flower visits, their presence within the crop impacts the behavior and performance of other individuals. Underscoring the importance of evaluating pollinator performance via multiple criteria, our results show that bee groups contribute to pollination in different ways. These differences may provide functional complementarity and stability of pollination services to agricultural systems.
With growing concern surrounding global pollinator declines, it is important to understand how habitat destruction and agricultural intensification impact pollinator communities. Euglossine bees are tropical forest-dependent pollinators responsible for pollination of both economically important crops and wild plant species. A growing body of work has focused on the effect of habitat fragmentation on euglossine bees, yet little is known about how these bees are impacted by agricultural intensification. Coffee cultivation is widespread in the tropics, and its management is conducted along a gradient of intensity, which ranges from monoculture (i.e., no shade, high inputs) to polyculture (shade overstory retained, fewer inputs). We used a landscape in Soconusco, Chiapas, Mexico, that allowed for comparison between monoculture and polyculture coffee farms, while holding distance to native habitat, as well as native habitat quality, constant. We found that habitat management influenced abundance, estimated richness, and community composition of euglossine bees. The polyculture coffee farm boasts a more similar community composition to the forest than to the monoculture coffee farm. In addition, the polyculture farm had almost double the euglossine abundance compared with the monoculture farm. Our results suggest that coffee management regimes may strongly impact euglossine communities and that less intensive polyculture approaches may mitigate species losses of this important group of pollinators.
The capybara, Hydrochoerus hydrochaeris (L.) (Rodentia: Caviidae), is the largest herbivorous rodent on Earth and abundant in the Neotropical region, which can provide a stable food source of dung for dung beetle communities (Coleoptera: Scarabaeidae: Scarabaeinae). However, the use of capybara dung by dung beetles is poorly known. Here, we present data on the structure of the dung beetle community attracted to capybara dung and compare with the community attracted to human feces. Dung beetles were captured with pitfall traps baited with fresh capybara dung and human feces in pastures with exotic grass (Brachiaria spp.), patches of Brazilian savanna (Cerrado), and points of degraded riparian vegetation along the Aquidauana river in Anasta´cio and Aquidauana, Mato Grosso do Sul, Brazil. In traps baited with human feces, 13,809 individuals of 31 species were captured, and in those baited with capybara dung 1,027 individuals belonging to 26 species were captured. The average number of individuals and species captured by the traps baited with human feces was greater than for capybara dung in all habitats studied. Composition of the communities attracted to human feces and capybara dung formed distinct groups in all habitats. Despite the smaller number of species and individuals captured in capybara dung when compared with human feces, capybara dung was attractive to dung beetles. In Brazil, the legalization of hunting these rodents has been debated, which would potentially affect the community and consequently the ecological functions performed by dung beetles that use the feces of these animals as a resource. In addition, the knowledge of the communities associated with capybaras may be important in predicting the consequences of future management of their populations.
A year-long flight phenology study was undertaken from 15 July 2009 to 7 July 2010 in central and southeastern Louisiana to estimate the temporal flight patterns of the three southeastern Ips species: Ips grandicollis (Eichhoff), Ips avulsus (Eichhoff), and Ips calligraphus (Germar) (Coleoptera: Curculionidae: Scolytinae) as well as some of their predatory and phloem-feeding coleopteran associates. The southeastern Ips species play important roles as decomposers in forest ecosystems, but can cause ecological and economic damage during epidemic population phases. In total, 282,761 individuals of the three southeastern Ips species were collected using Ips pheromone-baited multiple funnel traps during the study period. Two major Ips activity peaks were observed during 16 September to 7 October of 2009 and 24 March to 15 April of 2010. In total, 9,139 associated Coleoptera were also collected. Greater than 95% of the total number of associated Coleoptera collected were represented by histerids from the genus Platysoma (4,487; 49.1% of total), the trogossitid Temnoscheila virescens (F.) (2,107; 23.1%), cerambycids from the genus Monochamus (1,013; 11.1%), and Acanthocinus obsoletus (Olivier) (743; 8.1%), and the clerid Thanasimus dubius (F.) (477; 5.2%). Results showed that the associates fell into four temporal groups: the winter and spring active species T. dubius; the spring active species Rhagium inquisitor (L.) and histerids from the genus Platysoma; the spring and summer active species T. virescens, Buprestis lineata F., and Monochamus carolinensis (Olivier); and the summer through fall active species A. obsoletus and Monochamus titillator (F.).
The prevalence of the endosymbiont Wolbachia and its effects on mitochondria variation were analyzed in seven natural populations of Tetranychus truncatus Ehara (Trombidiformes: Tetranychidae) in current study. Five Wolbachia strains (wtru1, wtru5, wtru7, wtru8, and wtru12) were detected based on the surface protein of Wolbachia (wsp) sequence data and the multiple locus sequences typing data, suggesting that multiple separate invasions have occurred. Part of mitochondrial cytochrome oxidase subunit I gene was sequenced from infected individuals revealing 10 different haplotypes. As predicted, the haplotype and nucleotide diversity were lower in infected individuals than that in uninfected individuals. Furthermore, phylogenetic and analysis of molecular variance analyses revealed that the distribution of mtDNA haplotypes is not associated with geography. Rather, it is strongly concordant with infection status. These data support the hypothesis that Wolbachia infection can affect the genetic structure and diversity of the host mites.
The woodwasp Sirex noctilio F. (Hymenoptera: Siricidae) has become established in North America.Aprimary tactic for the management of S. noctilio in the southern hemisphere has been the development of a biological control agent, Deladenus siricidicola Bedding. This nematode has a bicyclic life cycle including a mycetophagous free-living and parasitic cycle. During oviposition, female Sirex woodwasps inject a symbiotic fungus. Because D. siricidicola only develops well on Amylostereum areolatum (Chaillet ex Fries) Boidin (Russulales: Amylostereaceae) and North American woodwasps were thought to all have Amylostereum chailletii (Persoon) Boidin as their fungal symbiont, the risk of unintended impacts from D. siricidicola in North America was considered low. Specific polymerase chain reaction primers were designed to amplify the intergenic spacer region of Amylostereum symbionts in a population of the native woodwasp Sirex nigricornis F. located in central Louisiana (i.e., well outside the known distribution of S. noctilio); identity of the symbiont was confirmed by phylogenetic analyses. Overall, 95 out of 100 fungal isolates obtained from the mycangia of S. nigricornis were identified as Amylostereum species. Contrary to expectations, 60% were identified as A. chailletii (N = 60), while 35% were identified as A. areolatum (N = 35). The remaining 5% of these isolates (N = 5) were identified as Bipolaris papendorfii (Aa) Alcorn, Alternaria alternata (Fr.) Keissl, Penicillium marneffei Segretain, Scytalidium cuboideum (Sacc. & Ellis) Sigler & Kang, and Hyphopichia heimii (Pignal) Kurtzman based on sequencing of the internal transcribed spacer (ITS) region. The five non-Amylostereum isolates were likely contaminants during mycangia-spore extraction process. This study confirms the presence of A. areolatum in a population of the native woodwasp S. nigricornis well outside the known distribution of S. noctilio.
Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae), commonly referred to as citrus blackfly, is a sap-sucking hemipteran insect. Although polyphagous, citrus is its most preferred host plant. Samples of this insect were collected from Murraya koenigii (L.). The cytochrome c oxidase subunit I gene (mtCO1)-based analysis by sequencing helped in molecular identification of the insect. Phylogenetic analysis of cytB-nd1-LrDNA showed the coevolution of A. woglumi with its primary bacterial symbiont Portiera. Sequencing a 16S rDNA library from insect DNA revealed three bacterial phylotypes, namely, Portiera, Wolbachia, and Erwinia chrysanthemi. Further, we used fluorescence in situ hybridization to visualize the endosymbionts in a whole mount of A. woglumi. Culturable bacteria were obtained on different media and were classified on the basis of 16S rDNA. In total, 30 bacterial phylotypes belonging to 14 different genera, namely, Bacillus, Kocuria, Micrococcus, Staphylococcus, Paenibacillus, Rhodococcus, Rummellibacillus, Arthrobacter, Curtobacterium, Psychrobacillus, Listeria, Brevibacillus, Bhargavae, and Pantoea, were isolated by culturable methods.
Bacterial symbionts infect most insect species, including important pests such as whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), and often exert important effects on host ecology. The facultative symbiont Hamiltonella is found at high frequencies in the B. tabaciMED (type: Mediterranean—MED) in China. The prevalence of this symbiont in natural populations suggests beneficial effects of infection or manipulation of host reproduction. To date, however, no empirical studies on the biological role of Hamiltonella on the host B. tabaci have been reported. Here, we investigated the effects of Hamiltonella infection on the sex ratio and several fitness parameters in B. tabaci MED by comparing Hamiltonella-infected whiteflies with Hamiltonella-free ones. We found that Hamiltonella-infected whiteflies produced significantly more eggs, exhibited significantly higher nymphal survival, faster development times, and larger adult body size in comparison with Hamiltonella-free whiteflies, while no evidence of reproductive manipulation by Hamiltonella were found in B. tabaci MED. In conclusion, Hamiltonella infection substantially enhanced B. tabaci MED performance. This beneficial role may, at least partially, explain the high prevalence of Hamiltonella in B. tabaci MED populations and may also contribute to their effectiveness in spread of the plant pathogens tomato yellow leaf curl virus.
To reduce populations of hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), >500,000 Sasajiscymnus tsugae (Sasaji and McClure) (Coleoptera: Coccinellidae) have been released in the Great Smoky Mountains National Park since 2002. To determine factors affecting establishment and recovery of these predatory beetles, 65 single release sites were sampled using beat sheets from 2008 to 2012. Several abiotic and biotic factors were evaluated for their association with establishment and recovery of S. tsugae. Information on predatory beetle releases (location, year of release, number released, and season of release), topographic features (elevation, slope, Beers transformed aspect, and topographic relative moisture index), and temperature data (minimum and maximum temperatures 1 d after release and average minimum and maximum temperatures 7 d after release) were obtained from Great Smoky Mountains National Park personnel. These factors were evaluated using stepwise logistic regression and Pearson correlation. S. tsugae was recovered from 13 sites 2 to 10 yr after release, and the greatest number was recovered from 2002 release sites. Regression indicated establishment and recovery was negatively associated with year of release and positively associated with the average maximum temperature 7 d after release and elevation (generally, recovery increased as temperatures increased). Several significant correlations were found between presence and number of S. tsugae and year of release, season of release, and temperature variables. These results indicate that releases of S. tsugae should be made in warmer (≈10–25°C) temperatures and monitored for at least 5 yr after releases to enhance establishment and recovery efforts.
A series of laboratory experiments was conducted using electrical penetration graph, salivary flange, and honeydew measurement to study the effects of feeding-induced intra- and interspecific interactions on feeding behavior and honeydew excretion between planthoppers Nilaparvata lugens (Stål) and Sogatela furcifera (Horva´th). Feeding-induced intra- and interspecific interactions affected many measures of feeding behavior. The number of salivary flanges, mean duration of pathway activities per insect, and mean duration from first probe to first sustained phloem ingestion for both N. lugens and S. furcifera were significantly shorter on rice plants with feeding-induced conspecific and heterospecific effects than those for planthoppers fed on control plants. Feedinginduced intra- and interspecific interactions also affected the duration per insect of phloem ingestion for both N. lugens and S. furcifera. The durations per insect of phloem ingestion on host plants with feeding-induced conspecific and heterospecific effects were significantly longer than those on control plants. An asymmetric facilitative effect of induced interspecific interactions on the weight of honeydew excreted was detected, because only the honeydew weights of S. furcifera were significantly increased by the induced heterospecific effect on both varieties. The results demonstrated that the facilitative effects on honeydew excretion were consistent with previously documented effects on performance. Both facilitative effects on honeydew excretion and performance were asymmetrical, with more benefits to S. furcifera from N. lugens. Such facilitative effects might be mainly related to altered nutrient status and induced allelochemistry in rice.
The grape mealybug, Pseudococcus maritimus (Ehrhorn), and European fruit lecanium scale, Parthenolecanium corni (Bouché), are the predominant species of Coccoidea in Washington State vineyards. The grape mealybug has been established as a vector of Grapevine leafroll-associated virus 3 (GLRaV-3) between wine grape (Vitis vinifera L.) cultivars, elevating its pest status. The objective of this study was to determine if GLRaV-3 could be transmitted between Vitis x labruscana L. and V. vinifera by the grape mealybug and scale insects. Three transmission experiments were conducted with regard to direction; from V. vinifera to V. x labruscana L., from V. x labruscana L. to V. x labruscana L., and from V. x labruscana L. to V. vinifera. Each experiment was replicated 15 times for each vector species. Crawlers (first-instars) of each vector species were allowed 1-wk acquisition and inoculation access periods. The identities of viral and vector species were confirmed by reverse transcription-polymerase chain reaction, cloning, and sequencing of species-specificDNAfragments.GLRaV-3wassuccessfully transmittedbyboth species in all experiments, although Ps. maritimus was a more efficient vector under our experimental conditions.Tothe best of our knowledge, this study represents the firstdocumentedevidence of interspecific transmission of GLRaV-3 between two disparate Vitis species. It also highlights the potential role of V. x labruscana L. intheepidemiologyofgrapevineleafroll disease asasymptomlesssourceofGLRaV-3inoculum.
Vectors of several economically important plant viruses have been shown to feed or settle preferentially on either infected or noninfected host plants. Recent research has revealed that the feeding or settling preferences of insect vectors can depend on whether a vector is inoculative (carries the virus). To explore the implications of such changes in vector preference for the spread of the pathogen, we create a basic model of disease spread, incorporating vector preferences for infected and noninfected plants dependent on whether the vector is inoculative. Previous modeling work assumed that vector preferences remain unchanged with vector infection status and showed that vector preference for infected host plants promotes disease spread when infected hosts are rare, whereas preference for noninfected hosts promotes spread once infected hosts become abundant. In contrast, our model shows that a change in preference following acquisition of the pathogen can increase pathogen spread throughout the epidemic if noninoculative vectors prefer infected plants and inoculative vectors prefer noninfected plants, as has been detected experimentally in two pathosys-tems. Our results show that conditional vector preference can substantially influence plant pathogen spread, with implications for agricultural and natural systems. Conditional preference as a component of virus manipulation of vector behavior is potentially more important for the understanding of plant disease spread than previously recognized.
Herbivores elicit a complex indirect and direct defense response in plants, but little is known about how defenses are expressed throughout a plant's life cycle. Here we report the characterization of direct and indirect defense profiles for two vegetative stages of maize, v1 and v3. Indirect defense expression was evaluated by measuring plant headspace volatiles in response to artificial herbivory and caterpillar feeding. To assess direct defense expression, transcripts of four proteinase inhibitors (PI) and larval performance were measured. Artificial herbivory significantly elevated total induced volatiles in v1 and v3 compared with controls, but this induction was marginal in v1 when compared with v3. Both maize stages produced similar total amounts of volatiles, accounting for fresh weight, of different compositions during caterpillar feeding. However, on a per-plant basis, v1 produced less volatiles compared with v3. In contrast, jasmonic acid levels, an indicator of an antiherbivore defense response, increased similarly in both stages. During caterpillar feeding, both developmental stages contained higher levels of PI transcripts compared with controls. However, v1 plants contained more cystatin-like PI transcripts and total larval mass was reduced compared with v3 plants. These results suggest that in maize, direct and indirect defenses against insect herbivory differ between seedling and juvenile plants.
The behavior of ectotherm organisms is affected by both abiotic and biotic factors. However, a limited number of studies have investigated the synergistic effects on behavioral traits. This study examined the effect of temperature and density on locomotor activity of Musca domestica (L.). Locomotor activity was measured for both sexes and at four densities (with mixed sexes) during a full light and dark (L:D) cycle at temperatures ranging from 10 to 40°C. Locomotor activity during daytime increased with temperature at all densities until reaching 30°C and then decreased. Highdensity treatments significantly reduced the locomotor activity per fly, except at 15°C. For both sexes, daytime activity also increased with temperature until reaching 30 and 35°C for males and females, respectively, and thereafter decreased. Furthermore, males showed a significantly higher and more predictable locomotor activity than females. During nighttime, locomotor activity was considerably lower for all treatments. Altogether the results of the current study show that there is a significant interaction of temperature and density on daytime locomotor activity of M. domestica and that houseflies are likely to show significant changes in locomotor activity with change in temperature.
A 4-yr field study was carried out to study the dispersal behavior of young larvae of the eastern spruce budworm (Choristoneura fumiferana Clemens) (Lepidoptera: Tortricidae) within and between crowns of balsam fir (Abies balsamea (L.) Miller), through the peak to decline of an outbreak. Newly hatched neonates, searching for overwintering sites in the fall, were frequently captured in sticky traps as they dispersed via “ballooning” (on silken threads) between and within tree crowns. A relatively small proportion of neonates were also captured on sticky tapes as they walked down the trunk toward the lower crown, where most larvae overwinter. In the spring, second-instar larvae (L2) searching for feeding sites also ballooned within and between trees, but were also frequently captured on traps on all crown levels as they walked up trunks. Over the course of our study, defoliation in our study trees increased, and current-year shoot availability decreased significantly, perhaps influencing L2 in search of food to disperse more frequently among hosts via ballooning. Results of our study suggest that the foraging priorities of neonates and L2 significantly influence larval dispersal behaviors and that spruce budworm larvae may vary behaviors in response to changing host condition during an outbreak.
Grape root borer, Vitacea polistiformis (Harris), is an oligophagous and potentially destructive pest of grape in commercial vineyards throughout much of the eastern United States. Larvae feed on vine roots, although little is known about their below-ground interactions with host plants. The behavioral response of groups of grape root borer neonates to stimuli from host and nonhost roots was evaluated in single and paired stimuli bioassays in which stimuli were presented in opposing wells attached to the bottom of petri dish arenas. Stimulus sources included root pieces and root headspace volatiles from 3309 and 420-A grape rootstocks (host) and apple (nonhost) and ethanol-based extracts of 3309 and 420-A roots. In single stimulus assays, signiFIcantly more larvae were recovered from wells containing grape roots, apple roots, grape extracts, and grape root volatiles than from control wells, but there was no significant response to volatiles collected from the headspace of apple roots. In paired stimuli assays, significantly more larvae were recovered from wells containing grape than apple roots. There was no difference in larval distribution between wells when 420-A and 3309 roots were presented simultaneously, although a significantly greater response to 3309 than 420-A root extract was recorded.Whensoil was added to the assays, significantly more larvae were recovered from wells containing grape roots than from those containing only soil, but this response was not detected in assays using buried apple roots. These results are discussed in relation to the plant—insect interactions between grape root borer larvae and their Vitaceae hosts.
Jana C. Lee, Peter W. Shearer, Luz D. Barrantes, Elizabeth H. Beers, Hannah J. Burrack, Daniel T. Dalton, Amy J. Dreves, Larry J. Gut, Kelly A. Hamby, David R. Haviland, Rufus Isaacs, Anne L. Nielsen, Tamara Richardson, Cesar R. Rodriguez-Saona, Cory A. Stanley, Doug B. Walsh, Vaughn M. Walton, Wee L. Yee, Frank G. Zalom, Denny J. Bruck
Drosophila suzukii (Matsumura), an invasive pest of small and stone fruits, has been recently detected in 39 states of the United States, Canada, Mexico, and Europe. This pest attacks ripening fruit, causing economic losses including increased management costs and crop rejection. Ongoing research aims to improve the efficacy of monitoring traps. Studies were conducted to evaluate howphysical trap features affect captures of D. suzukii.We evaluated five colors, two bait surface areas, and a top and side position for the fly entry point. Studies were conducted at 16 sites spanning seven states and provinces of North America and nine crop types. Apple cider vinegar was the standard bait in all trap types. In the overall analysis, yellow-colored traps caught significantly more flies than clear, white, and black traps; and red traps caught more than clear traps. Results by color may be influenced by crop type. Overall, the trap with a greater bait surface area caught slightly more D. suzukii than the trap with smaller area (90 vs. 40cm2). Overall, the two traps with a side-mesh entry, with or without a protective rain tent, caught more D. suzukii than the trap with a top-mesh entry and tent.
Bactrocera oleae (Rossi) (Diptera: Tephritidae, Dacinae) is an oligophagous species that feeds only on cultivated olives (Olea europaea L.) and its close relatives. Synchrony of seasonal activity patterns of B. oleae, the olive fruit fly with its host's phenology is therefore expected. The objective of this study was to monitor the male olive fruit fly response to female sex pheromone in the field. White sticky traps were deployed year round for 3 yr in an olive orchard in Oroville, CA. They were checked periodically, and flies captured were counted and sexed. Although males were captured regularly, the numbers of females captured on pheromone traps were negligible. Food-baited traps and water-baited traps were deployed to show the presence of flies in the field. Our hypothesis that males would respond to pheromone when females were available and olive fruits were susceptible for oviposition was partially supported. There were two peaks of high male captures in pheromone traps: spring and fall. In spring, females were available and mature but few acceptable olives were available for oviposition (no new crop olives yet). In fall, females were present but many of the new crop olives were already infested. The food baited traps confirmed the presence of flies in the field even when very few were being captured in the pheromone-baited traps. Traps containing only water caught only two flies showing that water alone or the trap type in itself was not attractive to files.
The recently introduced plataspid Megacopta cribraria (F.) can infest fields of soybean (Glycine max (L.) Merrill) in the southeastern United States. Grid sampling in four soybean fields was conducted in 2011 and 2012 to study the spatial distribution of M. cribraria adults, nymphs, and egg masses. Peak oviposition typically occurred in early August, while peak levels of adults occurred in mid-late September. The overall sex ratio was slightly biased at 53.1 ± 0.2% (SEM) male. Sweep samples of nymphs were biased toward late instars. All three life stages exhibited a generally aggregated spatial distribution based on Taylor's power law, Iwao's patchiness regression, and spatial analysis by distance indices (SADIE). Interpolation maps of local SADIE aggregation indices showed clusters of adults and nymphs located at field edges, and mean densities of adults were higher in samples taken from field edges than in those taken from field interiors. Adults and nymphs were often spatially associated based on SADIE, indicating spatial stability across life stages.
Identification of chemical compounds extracted from host plants that act as oviposition stimulants for pest insects has gained importance, because of the compounds' potential use in the manipulation of insect behavior in the field. However, for generalist insects, such as phytophagous pentatomids, the chemical basis for the selection of the host is not well-known. Insect response canvary according to the soybean genotypes. Chemical profile of soybean pods of cultivars ‘BRS 213′, ‘BRS267′, ‘BR-16′, and ‘IAC-100′ were compared regarding the feeding preference and oviposition of the stink bug Euschistus heros (F.). In the no-choice test, E. heros females showed longer feeding time on pods of BR-16 (132.6 min), followed by BRS 213 (128.0 min), BRS 267 (122.5 min), and IAC-100 (82.9min). In the choice test, there was no significant difference in the feeding time among cultivars. In the oviposition test, females deposited 60% of eggs on the pods of BRS 267, followed by BRS 213(27.3%), BR-16 (8.8%), and IAC-100 (3.9%). The chemical profile of BRS 267 including greater presence of reducing sugars and lack of isoflavone forms might explain the preference of E. heros to oviposite on it compared with the remaining cultivars tested.
The response of the codling moth (Cydia pomonella L. (Lepidoptera: Tortricidae)) to different emission values of its main pheromone component, 8E,10E-dodecadien-1-ol (codlemone), was investigated in three field trials conducted in plots without mating disruption treatments. Moth catches obtained in traps baited with pheromone dispensers were correlated with the corresponding codlemone release rates by multiple regression analysis. In a preliminary trial conducted in Lleida (NE Spain), a decreasing trend of captures was observed based on increasing pheromone levels. After this, the pheromone release profiles of the pheromone dispensers were studied, in parallel with the field trials, by residual codlemone extraction and gas chromatography quantification. In the trials carried out in Asturias (NW Spain), a correlation between trap catches and emission levels (within the range from 11 to 1,078 µg/d) was found and fitted a logarithmic model. Captures followed a decreasing linear trend in the range of emission rates from 11 to 134 µg/d. Given that release values comprised between 11 and 67 µg/d did not lead to significantly different catches in traps, this emission range could be considered to develop effective formulations for attraction purposes when mating disruption is not acting in the environment.
Mating disruption and mass trapping of Ostrinia furnacalis (Génuéé), often called the Asian corn borer, were incorporated with insecticides to reduce pesticide use. Pesticides alone are often ineffective owing to problems in timing applications before the larvae enter the protection of corn stalks. In addition, overuse of insecticides has caused environmental contamination and concerns about consumer health. In 2010, 15 insecticides were compared with mating disruption or mass trapping at various dispenser (disp.) densities for reducing egg masses, trap captures, and ear damage. Mass trapping with 30 and 40 disp./ha, mating disruption with 300 disp./ha, or endosulfan, chlorpyrifos, and monosultap (0.55, 0.35, and 0.55 kg/ha, respectively) gave ≈50% ear protection. In 2011, an insecticide alone, no treatments, pheromone alone, and pheromone insecticide were examined. The same insecticides in combination with mating disruption or mass trapping at ≧200 or≧20 disp./ ha gave >90% ear protection even when chemical applications were reduced to 1 from 3, and the rates were reduced 50–75%. Pheromone dispensers contained >50% of their initial load 30 d after exposure.
Pseudotheraptus wayi Brown (Heteroptera: Coreidae) is a major pest of cashew in East Africa, but little is known about its chemical ecology. Here, we show by using behavioral assays and chemical analysis that some components of cashew leaf volatiles are attractants for male P. wayi. By using a petri dish arena-EthoVision video-tracking assay, males oriented closer to crude cashew leaf odor than females. In coupled gas chromatography-electroantennographic detection analysis, we found that four components of cashew leaf volatiles that were identified by coupled gas chromatography-mass spectrometry and confirmed with authentic standards as (E)- and (Z)-β-ocimene, alloocimene, and (Z)-3-hexenyl butyrate appeared to elicit stronger and more consistent responses in male than female antennae. We recorded electroantennograms from antennae of either sex, which confirmed that antennal responses of males to synthetic components of the cashew leaf odor were stronger than those of females. In the petri dish arena-Etho Vision video-tracking assay, males oriented closer to the synthetic cashew leaf monoterpenes than females. Our results suggest that specific monoterpenes in cashew leaf volatiles may serve as candidate kairomones for males.
Off-host stages of temperate zone ectoparasites must overcome two challenges: coping with unfavorable seasons and synchronizing their life cycles with host availability. In general, little is known about the seasonal cycles of insect ectoparasites of warm-blooded animals. the current study investigates the unusual phenology of a viviparous hippoboscid fly, the deer ked (Lipoptena cervi L.), that parasitizes boreal cervids. Despite months of asynchrony in offspring production, the adults emerge synchronously in mid-August across the northern boreal zone. We examined the role of diapause variation in the synchronization of life cycles by testing adult emergence success and time in relation to offspring birth month (October to April) and with respect to chilling time and photoperiod. Unexpectedly, we found that photoperiod had no role in regulating the life cycle, but diapause was maintained as long as pupae were exposed to cold. Pupae born before February needed a slightly longer exposure to high temperatures to terminate diapause if the cold period was short. Despite the apparent importance of a long period of chilling for life cycle synchrony, it was not required to terminate diapause. this finding of cold mainly preventing, rather than promoting, diapause termination is not novel among temperate insects, but it is rare. Slow diapause termination as a response to exceptionally long exposure to high, not low, temperatures seems to be a cornerstone for synchronizing the life cycle in the deer ked.
The twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is an important agricultural pest. Population dynamics and pest outbreaks highly depend on the overwintering success of the mite specimens; therefore, it is necessary to assess winter survival dynamics of this pest. Seasonal changes in supercooling point (SCP) and acute cold tolerance (2-h exposure at -5, 10, -15, -20, -23, or -25°C) were assessed in field-collected females during the winter in 2010–2011 in Iran. The SCP values varied from a minimum of -30.5°C (January 2011) to a maximum of -12.6°C (April 2011 ). Significant differences were recorded in the SCP distribution patterns between autumn-and winter-sampled females, depicting the acquisition of cold hardiness over the winter. The mean ambient air temperature was the lowest in January (4°C), when the females showed the highest supercooling ability. Correlated patterns between monthly temperatures and acute cold tolerance also were found. At -20°C, the survival of the mites was very low (10%) when they were sampled in October 2010; whereas it was high (97.5%) in January 2011, before decreasing to 5% in April 2011. The present data show that T. urticae females are chill tolerant and capable of adjusting their cold tolerance over the winter season. Acute cold tolerance ( -15 and -20°C) and SCP represent valuable metrics that can be used for predicting the seasonal changes of the cold hardiness of T. urticae females.
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere