REVIEW

With the recent publication of the second report of the Intergovernmental Panel on Climate Change the evidence has become more convincing that not only is world climate changing but that these changes are likely to be caused by human activities. Climate change will have important implications for insect conservation and pest status. Under these circumstances it may be time to put more effort into investigating actual climate induced changes. The types of evidence required and available for such studies are discussed, with particular reference to the Lepidoptera. Preliminary results are presented on moth phenology from the Rothamsted Insect Survey which suggest that changes, consistent with climate change, can already be detected.     

Nectar sugar composition in angiosperms from Chaco and Patagonia (Argentina): an animal visitor's matter?

 We relate nectar sugar composition with floral visitors in samples from two biogeographic regions from Argentina: Chaco (99 spp. from its southern region) and Patagonia (48 spp. from its central region), using our own data published in earlier papers. The variables to be compared were sugar ratio and sucrose percentage. Differences in the sugar composition were observed when comparing both regions. Bee- and butterfly-visited Patagonian species showed lower sucrose percentages and sugar ratios than Chaquean species; i.e., a convergence in sugar composition was not verified. Moth-visited species showed a wide range of sucrose proportions and sugar ratios in both regions with no significant differences between them. As the differences found in sugar ratio between Chaco and Patagonia, according to the predominant pollinator guilds, may have been influenced by the sample size, we searched for similarities in sugar ratios between plants with the same visitor type in a comparative way, comparing our data pooled together against data by Baker and Baker's (1983a). Our data do not agree with theirs, i.e., no trends can be drawn for bees, moths, and butterflies sugar preferences. The exceptions were the hummingbird-visited species that showed a similar pattern in both cases, i.e., there is a convergence among plants offering nectar with a predominance of sucrose. To evaluate whether closely related species within a family have similar nectar composition and flower visitors, regardless of their region, sugar proportions were compared in several families. Hexose nectars were predominant in Asteraceae, Fabaceae, Solanaceae, and Verbenaceae, while sucrose nectars prevailed in Bromeliaceae and Onagraceae. Nectar composition seems to be a more conservative trait than flower morphology. This may be a reason to explain the absence of a convergence in sugar composition between plants growing in different biogeographical regions that share the same animal visitor guilds. Received August 27, 2002; accepted December 17, 2002 Published online: June 2, 2003     

Unlocking the potential of historical abundance datasets to study biomass change in flying insects

1. Trends in insect abundance are well established in some datasets, but far less is known about how abundance measures translate into biomass trends. Moths (Lepidoptera) provide particularly good opportunities to study trends and drivers of biomass change at large spatial and temporal scales, given the existence of long‐term abundance datasets. However, data on the body masses of moths are required for these analyses, but such data do not currently exist.
2. To address this data gap, we collected empirical data in 2018 on the forewing length and dry mass of field‐sampled moths, and used these to train and test a statistical model that predicts the body mass of moth species from their forewing lengths (with refined parameters for Crambidae, Erebidae, Geometridae and Noctuidae).
3. Modeled biomass was positively correlated, with high explanatory power, with measured biomass of moth species (R² = 0.886 ± 0.0006, across 10,000 bootstrapped replicates) and of mixed‐species samples of moths (R² = 0.873 ± 0.0003), showing that it is possible to predict biomass to an informative level of accuracy, and prediction error was smaller with larger sample sizes.
4. Our model allows biomass to be estimated for historical moth abundance datasets, and so our approach will create opportunities to investigate trends and drivers of insect biomass change over long timescales and broad geographic regions.

     

Role of host-plant stimuli in sexual behaviour of small ermine moths (Yponomeuta)

ABSTRACT. 1. Studies involving experiments with olfactometers and field experiments have shown that the release of sex-pheromone by females of Yponomeuta spp. is stimulated by the presence of host plants.
2. While in Y.evonymellus L. less females emitted pheromone in the absence of host plants, in Y.padellus L. the initiation of pheromone release was delayed.
3. Females of Y.evonymellus, Y.cagnagellus Hüb., Y.padellus and Y.plumbellus D. & S. all preferred a place with host-plant odour to one with non-host odours for sex-pheromone release.
4. Male preference for host-plant odour was demonstrated in the laboratory only for Y.cagnagellus.
5. Trap catches in the field indicated a reinforcement of female attractiveness by host-plant stimuli.     

Otoacoustic emissions from insect ears having just one auditory neuron

Sensitive hearing organs often employ nonlinear mechanical sound processing which produces distortion-product otoacoustic emissions. Such emissions are also recorded from insect tympanal organs. Here we report high frequency distortion-product emissions, evoked by stimulus frequencies up to 95 kHz, from the tympanal organ of a notodontid moth, Ptilodon cucullina, which contains only a single auditory receptor neuron. The 2f1–f2 distortion-product emission reaches sound levels above 40 dB SPL. Most emission growth functions show a prominent notch of 20 dB depth (n = 20 trials), accompanied by an average phase shift of 119°, at stimulus levels between 60 and 70 dB SPL, which separates a low- and a high-level component. The emissions are vulnerable to topical application of ethyl ether which shifts growth functions by about 20 dB towards higher stimulus levels. For the mammalian cochlea, Lukashkin and colleagues have proposed that distinct level-dependent components of nonlinear amplification do not necessarily require interaction of several cellular sources but could be due to a single nonlinear source. In notodontids, such a physiologically vulnerable source could be the single receptor cell. Potential contributions from accessory cells to the nonlinear properties of the scolopidial hearing organ are still unclear.     

Types of oreal and oreotundral disjunctions in the western Palearctic

The cyclic changes of the Pleistocene between cold and warm periods resulted in antagonistic responses within two different groups of organisms: one expanding during the warm periods and retracting during the cold phases and another with opposed responses. The latter group is composed of so-called arctic and alpine species. These species have recently become the focus of phylogeographical research. However, we still lack a comprehensive characterization of the different types of alpine and arctic-alpine disjunctions in the western Palearctic. Such an overview might facilitate the selection of different model species to test the different patterns of disjunctions for congruences revealing their past distribution. Therefore, we list all alpine and arctic-alpine disjunction types of the western Palearctic using butterflies and moths as a model group. We distinguish between (1) endemics of the Alps (α) with strongly restricted and (β) with broader distributions; (2) alpine disjunct species (α) with perialpine disjunctions and (β) with a wide western Palearctic distribution; (3) oro-Mediterranean species; and (4) arctic-alpine disjunct species. These types of distributions and further subtypes are exemplified using chorological data of butterfly and moth species. In this context, we discuss the intraspecific differentiation and the differentiation among sibling-species within and among disjunct parts of the distribution area. We also formulate hypotheses of the distribution patterns during the last ice age which might best explain the actual patterns. Finally, we suggest some case studies of genetic analyses to test the above mentioned hypotheses.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 415–430.