32,548 research outputs found
Expansion of the winter moth outbreak range : no restrictive effects of competition with the resident autumnal moth
No full text1. Both direct and indirect competition can have profound effects on species abundance and expansion rates, especially for a species trying to strengthen a foothold in new areas, such as the winter moth (Operophtera brumata) currently in northernmost Finland. There, winter moths have overlapping outbreak ranges with autumnal moths (Epirrita autumnata), who also share the same host, the mountain birch (Betula pubescens ssp. czerepanovii). Competitive interactions are also possible, but so far unstudied, are explanations for the observed 1–3 years phase lag between the population cycles of the two moth species. 2. In two field experiments, we studied host plant-mediated indirect inter-specific competition and direct interference/exploitation competition between autumnal and winter moths. The experimental larvae were grown either with the competing species or with the same number of conspecifics until pupation. Inter-specific competition was judged from differences in pupal mass (reflecting lifespan fecundity), larval development time and larval survival. 3. Larval performance measurements suggested that neither direct nor indirect interspecific competition with the autumnal moth reduce the growth rate of winter moth populations. Winter moths even had a higher probability of survival when reared together with autumnal moths. 4. Thus, we conclude that neither direct nor indirect inter-specific competition is capable of suppressing the spread of the winter moth outbreak range and that both are also an unlikely cause for the phase lag between the phase-locked population cycles of the two moth species
Disputatio inauguralis de pleuritide legitima
No full textquam ... pro summis in arte medica honoribus, insignibus & privilegiis doctoralibus, rite ac legitime assequendis & obtinendis ... publice examinandam proponit Paulus Moth Flensburgo-Holsatus. Anno ... M DC XXXVII. die ... Mensis SeptembrisDatum auf Titelblatt hs. ergänzt und geändert: Anno ... M DC XXXVII. die 4. Mensis OctobrisEnth. 50 ThesenDiss. med. Basel, 163
Optimization of moth-eye antireflection schemes for silicon solar cells
No full textNanostructured moth-eye antireflection schemes for silicon solar cells are simulated using rigorous coupled wave analysis and compared to traditional thin film coatings. The design of the moth-eye arrays is optimized for application to a laboratory cell (air–silicon interface) and an encapsulated cell (EVA-silicon interface), and the optimization accounts for the solar spectrum incident on the silicon interface in both cells, and the spectral response of both types of cell. The optimized moth-eye designs are predicted to outperform an optimized double layer thin film coating by approximately 2% for the laboratory cell and approximately 3% for the encapsulated cell. The predicted performance of the silicon moth-eye under encapsulation is particularly remarkable as it exhibits losses of only 0.6% compared to an ideal AR surfac
Reversed impacts by specialist parasitoids and generalist predators may explain a phase lag in moth cycles : a novel hypothesis and preliminary field tests
No full textAmong cyclic populations of herbivores, inter-specific temporal synchrony has been attributed to both climatic factors and trophic interactions. In northern Europe, winter and autumnal moths undergo regular 9–11 year population cycles. The winter moth cycle has typically been phase-locked with that of the autumnal moth, but with a 1–3- year phase lag. We examined potential effects of natural enemies on this phase lag using field experiments and observational data. We found that larval parasitism was significantly higher in autumnal than in winter moths. Conversely, pupal predation by generalist invertebrates was clearly greater in winter than in autumnal moths. The difference in parasitism rates may contribute to the earlier collapse of the autumnal moth cycle. In addition, the phase lag may be strengthened by higher pupal mortality in winter moths in the early increase phase of the cycles. As a consequence, we put forward a hypothesis on reversed effects of natural enemies, providing a potential explanation for phase-lagged population cycles of these moth species
Larval parasitism of the autumnal moth reduces feeding intensity on the mountain birch
No full textPlants respond to grazing by herbivorous insects by emitting a range of volatile organic compounds, which attract parasitoids to their insect hosts. However, a positive outcome for the host plant is a necessary precondition for making the attraction beneficial or even adaptive. Parasitoids benefit plants by killing herbivorous insects, thus reducing future herbivore pressure, but also by curtailing the feeding intensity of the still living, parasitised host. In this study, the effect of parasitism on food consumption of the 5th instar larvae of the autumnal moth (Epirrita autumnata) was examined under laboratory conditions. Daily food consumption, as well as the duration of the 5th instar, was measured for both parasitised and non-parasitised larvae. The results showed that parasitism by the solitary endoparasitoid Zele deceptor not only reduced leaf consumption significantly but also hastened the onset of pupation in autumnal moth larvae. On the basis of the results, an empirical model was derived to assess the affects on the scale of the whole tree. The model suggests that parasitoids might protect the tree from total defoliation at least at intermediate larval densities. Consequently, a potential for plant–parasitoid chemical signalling appears to exist, which seems to benefit the mountain birch (Betula pubescens ssp. czerepanovii) by reducing the overall intensity of herbivore defoliation due to parasitism by this hymenopteran parasitoid
Shifting body weight-fecundity relationship in a capital breeder : maternal effects on egg numbers of the autumnal moth under field conditions
No full textIn the literature, various environmental factors are described as being capable of influencing the reproductive output of insect females irrespective of their body size. Still, female body size or weight is widely used as a proxy for fecundity. In the present study, a seven-year data set on the autumnal moth, Epirrita autumnata (Borkhausen) (Lepidoptera: Geometridae), was used to analyze whether the body weight-fecundity relationship in this capital breeding, cyclic forest defoliating lepidopteran is constant across years. Ambient temperature conditions and density of conspecifics during larval development, the length of the pupal period, as well as moth densities in the parent generation were examined as factors capable of modifying the body weight-fecundity relationship. While the regression slope of potential fecundity (total egg numbers per female) on pupal mass was constant across years, the mean total egg number per given body weight (the regression intercept) was significantly different between years. This residual variance in egg numbers after controlling for the effect of pupal mass was best explained by the pooled geometrid density (autumnal and winter moths) in the parent generation. The total egg number per given body weight decreased with increasing density of geometrid moths in the parent generation. Thus, maternal density effects on offspring fecundity were found in this system. Their rather weak nature suggests, however, that this maternal effect alone does not have the potential of causing cyclic population dynamics in the autumnal moth
Differential sperm expenditure reveals a possible role for post-copulatory sexual selection in a lekking moth
No full textCordes N, Yiğit A, Engqvist L, Schmoll T. Differential sperm expenditure reveals a possible role for post-copulatory sexual selection in a lekking moth. Ecology and Evolution. 2013;3(3):503-511
Manual versus automatic moth sampling at equal light sources – a comparison of catches from Mt. Kilimanjaro.
No full textNocturnal moth ensembles are frequently assessed using either catches from automatic light traps or manually collected samples at artificial light sources. Up to now, Few studies have compared the influence of these methodological differences on the samples. We compared such samples, attracted by identical light sources , using geometrid moths in the montane rainforest belt of Mt. Kilimanjaro, Tanzania, as an example. The average number of moths caught manually from 1900 h to 2200 h at a light tower - a reflective gauze cylinder with a lamp placed in the middle - was more than ten times higher than that caught in a light trap, with more than half of all spccies only recorded at the light tower. With regard to individuals sampled, catches were biased towards the subfamily Ennorninac in the traps (.51 % versus 30%) and towards Larentiinae in the manual samples (68% versus 44%). It remains to be tested whether the relatively higher representation of larger-sized Ennominae in the trap catches is due to later flight activity m SOlne behavioral differences related to body size. Diversity (measured as Fisher's alpha) oT light tower catches decreased from clearings (22.4) and secondary forest (21.7) to mature forest (11.0), whjle in the traps, values increased in the same order (Fisher's alpha: 6.0, 12.0, and 14.2). Species composition of trap samples taken in clearings and secondary forcst differed strongly from manual catches, while manual and automatic samples from mature forest were more similar to each other. Manual moth sampling at light towers proved superior to automatic light traps in many ways and is hence recommended as a very useful standard method to record nocturnal inseds if sufficient man-power is available
Male oriental fruit moth response to a combined pheromone-based attracticide formulation targeting both oriental fruit moth and codling moth (Lepidoptera: Tortricidae)
No full textAbstract: Combined attracticide formulations targeting Oriental fruit moth, Grapholita molesta (Busck), and codling moth, Cydia pomonella (L.), were tested in a field trapping experiment. Capture of male codling moths in traps baited with the combined formulation was reduced compared with traps baited with the codling moth formulation alone, whereas capture of male Oriental fruit moth was increased compared with traps baited with the Oriental fruit moth formulation alone. Subsequent wind tunnel experiments showed that a single locus of the mixed attracticide formulation or close parallel presentation of the two formulations enhanced source contact by male Oriental fruit moths but did not influence earlier behaviours. However, the two formulations presented in a serial arrangement to Oriental fruit moth rnales in the wind tunnel resulted in enhanced lock-on, upwind flight, and source contact behaviours. In addition, male Oriental fruit moths remained on mixed pheromone droplets of the paste matrix longer than on droplets of the Oriental fruit moth formulation alone. The increased time spent on the mixed droplet was correlated with a more rapid poisoning and a greater proportion of poisoned males compared with males exposed to the Oriental fruit moth attracticide alone. These results demonstrate that a combined attracticide formulation will have different effects on each of the targeted species. it is anticipated that, due to decreased attractiveness, a combined formulation would be less effective against the codling moth. However, a mixed formulation, due to increased attractiveness and toxicity, could be more effective against the Oriental fruit moth under field conditions
Floral to green: mating switches moth olfactory coding and preference
No full textMating induces profound physiological changes in a wide range of insects, leading to behavioural adjustments to match the internal state of the animal. Here, we show for the first time, to our knowledge, that a noctuid moth switches its olfactory response from food to egg-laying cues following mating. Unmated females of the cotton leafworm (Spodoptera littoralis) are strongly attracted to lilac flowers (Syringa vulgaris). After mating, attraction to floral odour is abolished and the females fly instead to green-leaf odour of the larval host plant cotton, Gossypium hirsutum. This behavioural switch is owing to a marked change in the olfactory representation of floral and green odours in the primary olfactory centre, the antennal lobe (AL). Calcium imaging, using authentic and synthetic odours, shows that the ensemble of AL glomeruli dedicated to either lilac or cotton odour is selectively up- and downregulated in response to mating. A clear-cut behavioural modulation as a function of mating is a useful substrate for studies of the neural mechanisms underlying behavioural decisions. Modulation of odour-driven behaviour through concerted regulation of odour maps contributes to our understanding of state-dependent choice and host shifts in insect herbivores
- …
