In herbivorous insects, differences in the degree of specialization to host plants emerge when the distribution of an herbivore differs from that of its host plants, which results in a mosaic of populations differing in performance on the different host plants. Using a specialized butterfly, Battus polydamas archidamas Boisduval, 1936, which feeds exclusively on the genus Aristolochia, we test whether host plant co-occurrence and associated differences in host quality modify local adaptation in terms of larval preference and performance. We compared individuals from a monospecific host stand of Aristolochia chilensis with those from a mixed host stand of A. chilensis and A. bridgesii. Individuals were reared in a reciprocal transfer experiment in which source population and the host species fed to larvae were fully crossed in a two-by-two factorial experiment in order to quantify their preference, performance (development time, size and growth rate) and survival. Individuals from both populations preferred the species they ate during their larval development over the other host, which indicates host plant-induced preference with non-adaptive implications. Larvae from mixed and monospecific stands grew faster and survived better when reared on A. bridgesii than A. chilensis. Larvae from a monospecific host stand grew slower and fewer individuals survived under the same local conditions, which is contrary to expectations. Therefore, rearing the butterfly on A. bridgesii consistently resulted in better performance, which indicates that the monospecific population is less well adapted to its host than the mixed population. Variation in the occurrence of the two host plants in the two populations can result in divergent selection due to the variation in plant quality, which in this case could result in opposing adaptive processes., Rodrigo S. Rios, Cristian Salgado-Luarte, Gisela C. Stotz, Ernesto Gianoli., and Obsahuje bibliografii
The Chinese pine caterpillar Dendrolimus tabulaeformis is an important destructive leaf borer in boreal coniferous forests in China. This species overwinters in the larval stage. Changes in supercooling capacity and physiological-biochemical parameters of D. tabulaeformis larvae from a natural population were evaluated at different stages during the overwintering period. Cold hardiness of overwintering larvae collected in January was significantly greater than that of larvae collected in other months. January larvae survived for 15 days at -10°C and for approximately 2 days at -15°C. By contrast, larvae collected in September survived for no more than 4 h at -5°C and those in November and March no more than 1 day at -15°C. Supercooling point gradually decreased from -5.9 ± 0.3°C in September to a minimum of -14.1 ± 1.0°C in November, then gradually increased to the original value with the advent of spring. Water content gradually decreased from September to November, remained at approximately 74.5% until March and then gradually increased to levels similar to those in September. The lipid content gradually decreased from September to November, remained stable at approximately 3.2% until March and then gradually increased to levels similar to those in September. Glycogen content increased to a peak in November and then decreased. The concentrations of several metabolites showed significant seasonal changes. The most prominent metabolite was trehalose with a seasonal maximum in November. Glucose levels were highest in January and then gradually decreased until in May they were at levels similar to those in September. Glycerol levels remained relatively stable during winter but increased significantly in May. This study indicates that D. tabulaeformis is a freeze-avoidant insect. Larvae increase their supercooling capacity by regulating physiological-biochemical parameters during overwintering., Yuying Shao, Yuqian Feng, Bin Tian, Tao Wang, Yinghao He, Shixiang Zong., and Obsahuje bibliografii
We studied a population of the regionally endangered marsh fritillary butterfly Euphydryas aurinia inhabiting a system of loosely connected dry calcareous grasslands in sub-Mediterranean Slovenia. Our goal was to set the basis for a long-term monitoring of this butterfly in four meadows using mark-release-recapture (MRR). We determined its demographic parameters, dispersal, behaviour and utilization of nectar plants in different quality patches. Total population size was estimated to be approximately 347 males (95% confidence interval: 262-432) and 326 females (95% confidence interval: 250-402), with an unbiased sex ratio. The average lifespans were 6.3 and 8.6 days, respectively. Daily population sizes followed a parabola with marked protandry. Both sexes were relatively highly mobile with both occasionally moving over half a kilometre. The spatial distribution of animals seemed to be associated with patch size, host plant densities and nectar sources, resulting in much higher population densities in the largest patch. Adult behaviour differed between the sexes, with females resting more and flying less than males. Behaviour also changed during daytime and with the progression of the season. Adults were confirmed to be opportunistic feeders, since as many as ten nectar sources were detected. We conclude that demographic parameters differ greatly among regions and habitats, thus conservation aims should be planned accordingly. Although the population studied is apparently in good condition, there are threats that may hamper the long-term persistence of the species in this area: succession, intensification of mowing and overgrazing., Jure Jugovic, Costanza Uboni, Sara Zupan, Martina Lužnik., and Obsahuje bibliografii
Estimating the spatial dispersion of pest arthropods is crucial for the development of reliable sampling programs and one of the main components of integrated pest management. The natural spatial distribution of a population of a species may be random, uniform, or aggregated and can be so classified based on calculation of variance to mean relations and related dispersion indices. In this work some classical density-invariant dispersion indices and related regression models are used for the first time to quantify the spatial dispersion of an important peach pest Anarsia lineatella Zeller (Lepidoptera: Gelechiidae) and construct fixed precision sequential sampling schemes. Taylor's power law, Iwao's patchiness regression and Nachman's model were used to analyse the damage to peaches caused by A. lineatella. All three regression models fit the data well, although the results indicate that Iwao's patchiness model provides a better description of the relationship between variance and mean density. Taylor's b and Iwao's b regression indices were both significantly smaller than 1, indicating that the distribution of individuals was uniform rather than random or aggregated. According to Green's and Kuno's models, the minimum sample size at the precision level of 0.2 varies from 3 samples, when total population density is more than 3 larvae/sample, to 10 samples, when population density is between 1 and 2 larvae/sample. Kuno's fixed sampling plan indicates that a small number of samples (i.e., 3-10 branches with fruit) is sufficient to estimate the mean population density of A. lineatella larvae with a precision of 0.2. The Resampling for validation of sampling plans (RVSP) method confirmed that the average level of precision of the fixed sequential plans matched the desired precision in most cases. The sampling plan presented here provides a level understanding of A. lineatella spatial ecology suitable for pest manage, Petros Damos., and Obsahuje bibliografii
This note aims to put on record a hitherto unreported function of caterpillar setae supplementary to those already known. When woolly bear caterpillars of the moth Lemyra imparilis (Butler) have their body hairs removed and are dropped into a bucket of water from a height of 30 cm, they sink immediately. Caterpillars, however, with an intact coat of hairs usually float. This hitherto unreported role of caterpillar setae as life-rafts should depend on a high contact angle θe, and thus on the position, density and dimensions of the hairs. An SEM examination of the surface structure of the setae revealed a system of fine grooves and small distally pointing barbs on the hair shaft, which can trap air to support the weight of the insect. Insect setae generally and body hairs of caterpillars in particular are known to possess many functions, but a role as life-rafts for caterpillars in danger of drowning can now be added to the list of possible uses of body hairs., V. Benno Meyer-Rochow., and Obsahuje bibliografii
A new species of Lymanopoda Westwood, a cloud forest Neotropical genus of Satyrinae, is described from the páramo grasslands on an isolated, peripheral massif in the Colombian Central Cordillera of the Andes: L. flammigera Pyrcz, Prieto & Boyer, sp. n. The genus Lymanopoda is species-rich (approx. 65 species) and its alpha taxonomy is relatively well researched. Relationships within the genus using molecular data have also been explored. The new species is outstanding for its golden yellow colour in males, not found in any other neotropical Satyrinae. Cladograms were constructed based on COI sequences of 47 species of Lymanopoda (~ 70% of the known species) including 17 from Colombia. The new species segregates in the "tolima" clade, which comprises four other high altitude Colombian species, as well as two from Ecuador. However, it is the comparative analysis of male genitalia, in particular the superuncus and valvae, which identified its closest relatives, thus confirming that genital characters can help refine molecular phylogenies. In addition to identifying species using mitochondrial DNA (mtDNA barcodes), nucleotide sites with unique fixed states used to identify nine species of Lymanopoda from Colombia are also presented., Tomasz W. Pyrcz, Carlos Prieto, Pierre Boyer, Jadwiga Lorenc-Brudecka., and Obsahuje bibliografii
The potato tuberworm, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is a major pest of potato, Solanum tuberosum L. (Solanales: Solanaceae), both in the field and storehouses. The rate of development and survival of P. operculella, reared on potato tubers cv. Spunta at eight constant temperatures (17.5, 20, 22.5, 25, 27.5, 30, 32.5 and 35°C), were studied in the laboratory. The duration of development of the immature stages was recorded. Adult longevity was also recorded under the same conditions. Developmental time decreased significantly with increase in temperature within the range 17.5-32.5°C. No development occurred at 35°C. Survival (%) from egg to adult was higher at temperatures within the range 17.5-27.5°C than at either 30 or 32.5°C. Linear and a non-linear (Logan I) models were fitted to our data in order to describe the developmental rate of the immature stages of P. operculella as a function of temperature and estimate the thermal constant (K) and critical temperatures (i.e., lower developmental threshold, optimum temperature for development, upper developmental threshold). Lower developmental threshold and optimum temperature for development ranged between 12.5-16.2 and 31.7-33.8°C, respectively. The estimated upper developmental threshold for total immature development was 35.0°C. Thermal constant for total development was 294.0 degree-days. Adult longevity was significantly shorter at high (30 and 32.5°C) than at low temperatures (17.5-27.5°C). Our results not only provide a broader insight into the thermal biology of P. operculella, but also can be used as an important tool in planning an effective pest control program both in the field and storehouses., Stefanos S. Andreadis, Christos G. Spanoudis, Georgia Zakka, Barbara Aslanidou, Sofia NoukariI, Matilda Savopoulou-Soultani., and Obsahuje bibliografii
Facultative diapause in the wax moth, Galleria mellonella, occurs in the final larval instar. Application of juvenile hormone analogs (JHAs) to the larvae of this species has similar effects to diapause, in terms of prolonged development of the larval stages and the arrest in the metamorphosis of internal organs. Here, we focus on testes development and spermatogenesis at the end of larval development in G. mellonella, how they are affected by diapause induced by an environmental decrease in temperature to 18°C and the application of a JHA (fenoxycarb) to larvae. Because neither testis development nor spermatogenesis are described in detail for this species, we examined them in individuals not in diapause during the period from the last larval instar to the newly emerged adult and present a timetable of changes that occur in the development of testes in this species. These observations have increased the very limited data on the course of spermatogenesis in pyralid insects. We then used these data for comparative analysis of testes in larvae from two experimental groups: individuals in diapause and those treated with fenoxycarb. The results on the general morphology testes revealed obvious degenerative changes caused by fenoxycarb (but not by diapause), including testicular wall hypertrophy and disarrangement of testicular follicles. Moreover, treatment with fenoxycarb finally resulted in the disintegration of nearly all testicular cyst-containing germ cells at different stages of spermatogenesis, a situation never previously described in the literature. In contrast, the main effect of diapause on testes was merely the degeneration of spermatocytes in the proximal regions of the testicular follicles. Finally, the TUNEL analyses, revealed that the degenerative changes in germ cells were apoptotic in character in the testes of both individuals in diapause and fenoxycarb-treated males., Piotr Bebas, Bronislaw Cymborowski, Michalina Kazek, Marta Anna Polanska., and Obsahuje bibliografii
We investigated the effect of the feeding behaviour of young larvae of Pieris rapae crucivora Boisduval (Pieridae) on parasitism by the parasitoid wasp, Cotesia glomerata (L.) (Braconidae). Young, 1st-3rd instar larvae used approximately three sites for feeding each day. When not feeding, they moved a short distance away from the feeding sites (= feeding marks) and rested. For first, second and third instar larvae, the distances from the new mark, made within 24 h, to larva at rest were, respectively, about 3.5 mm, 5 mm and more than 10 mm. To resume feeding, they moved back to one of the former feeding sites or a new site. The percentage of the feeding marks older than 24 h that attracted parasitoids was less than 50%. Time spent searching for hosts by a parasitoid was short. Larvae placed 5 mm or more from a feeding mark were less parasitized than the larvae placed near a mark. The number of feeding marks affected parasitism. When comparing single-marked and triple-marked leaves, the percentage parasitism of the larvae on the latter was significantly lower than that of the larvae on the former. On triple-marked leaves, parasitoids visited each mark unevenly. Accordingly, the time spent searching each mark differed significantly among the marks. Because of this confusing effect, hosts are considered to be reducing the risk of parasitism. Our results demonstrate that the feeding habits of young larvae of P. rapae crucivora are adaptive in terms of reducing the risk of parasitism by C. glomerata., Aya Nakayama, Keiji Nakamura, Jun Tagawa., and Obsahuje bibliografii
Climate change scenarios predict losses of cold-adapted species from insular locations, such as middle high mountains at temperate latitudes, where alpine habitats extend for a few hundred meters above the timberline. However, there are very few studies following the fates of such species in the currently warming climate. We compared transect monitoring data on an alpine butterfly, Erebia epiphron (Nymphalidae: Satyrinae) from summit elevations of two such alpine islands (above 1300 m) in the Jeseník Mts and Krkonoše Mts, Czech Republic. We asked if population density, relative total population abundance and phenology recorded in the late 1990s (past) differs that recorded early in 2010s (present) and if the patterns are consistent in the two areas, which are separated by 150 km. We found that butterfly numbers recorded per transect walk decreased between the past and the present, but relative population abundances remained unchanged. This contradictory observation is due to an extension in the adult flight period, which currently begins ca 10 days earlier and lasts for longer, resulting in the same total abundances with less prominent peaks in abundance. We interpret this development as desynchronization of annual cohort development, which might be caused by milder winters with less predictable snow cover and more variable timing of larval diapause termination. Although both the Jeseník and Krkonoše populations of E. epiphron are abundant enough to withstand such desynchronization, decreased synchronicity of annual cohort development may be detrimental for innumerable small populations of relic species in mountains across the globe., Martin Konvička, Jiří Beneš, Oldřich Čížek, Tomáš Kuras, Irena Klečková., and Obsahuje bibliografii