In insects, allometries of exaggerated traits such as horns or mandibles are often considered species specific and constant during a season. However, given that constraints imposed by the advancing season affect the developmental processes of organisms, these allometries may not be fixed, and the switch point between morphs may vary between populations and within populations during a season. The hypothesis of such a seasonal variation in exaggerated traits was tested using the dimorphic males of the beetle Lucanus cervus. The remains of specimens killed by predators were collected along forest tracks from mid May to late August 2008 in a protected lowland forest in northern Italy. The largest beetles were collected in mid May and average size thereafter decreased. Males collected early in the season mostly had large mandibles (i.e. they belonged to the major morph). In contrast, late in the season the probability of finding males with large mandibles was very low. The threshold body size determining morph expression also shifted during the season. Early in the season, the threshold pronotum width for a 50% chance of developing into the major morph was 1.74 cm, whereas later in the season it was 1.90 cm. This shift in the threshold body size was interpreted as the effect of phenotypic plasticity in a population exposed to constraints imposed by the advancing season. and Sönke Hardersen, Anna L.M. Macagno, Roberto Sacchi, Ilaria Toni.
Laboratory experiments were conducted to examine the effects of photoperiod and temperature on the pupation behaviour of the parasitoid, Microplitis mediator (Haliday) (Hymenoptera: Braconidae), parasitizing larvae of Mythimna separata Walker (Lepidoptera: Noctuidae). A combination of long photoperiod (14 + h L) and warm temperatures (20–24°C) caused parasitized caterpillars to climb to upper plant parts where the parasitoid produced a green, non-diapausing cocoon on a green leaf, initially retaining the dying caterpillar host as a protective covering. In contrast, short photoperiod (8–10 h L) and low temperature (16–18°C) induced host caterpillars to descend the plant where the parasitoid produced a brown, diapausing cocoon either hanging by silk from a senescing leaf or simply lying on the soil, but without any continued association with the host. These findings illustrate the potential for seasonal environmental cues to simultaneously mediate diapause induction, cocoon polymorphism, and alternate forms of host behaviour modification in a hymenopterous parasitoid., Shu Ping Luo ... [et al.]., and Obsahuje seznam literatury
Species in the carnea complex of the common green lacewing are predators of the common pistachio psylla, Agonoscena pistaciae in both cultivated pistachio plantations and on wild pistachio plants in Iran. The seasonal occurrence of common green lacewings was monitored in pistachio orchards from 2007 to 2008. In addition, the effect of different temperature regimes on preimaginal development, survival and prey consumption of the predatory lacewing Chrysoperla lucasina fed on A. pistaciae nymphs were studied under controlled conditions. The adults of common green lacewings first appeared on pistachio trees in mid April and were most abundant in early July, decreased in abundance in summer and increased again in October. The relative density of common green lacewings was higher in pistachio orchards where the ground was covered with herbaceous weeds than in those without weeds. In the laboratory females of C. lucasina laid an average of 1085 eggs over 60 days at 22.5°C. The maximum prey consumption occurred at 35°C when the larvae consumed 1812 fourth instar psyllid nymphs during their larval period. The intrinsic rate of natural increase (rm) was 0.11. The total development (egg-adult) required 385 degree-days above the theoretical lower developmental threshold of 9.6°C. and Fatemeh KAZEMI, Mohammad Reza MEHRNEJAD.
The populations of the firebug Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae) in Europe exhibit three kinds of host plant associations: feeding on seeds of (1) Tilia spp. (Tiliaceae), (2) Malvaceae (s. str.), and (3) Robinia pseudacacia (Fabaceae). The three host plant taxa often grow in different habitats and localities. We have tested the hypothesis that P. apterus forms on different host plants specialised "trophic populations" which also influence its food preference. We have collected P. apterus from localities with Tilia platyphyllos, Malva neglecta or Robinia pseudacacia as host plants and tested their preferences in a multiple choice test involving seeds of Tilia cordata, T. platyphyllos, Althaea officinalis, Alcea rosea and Robinia pseudacacia. The original host plant of P. apterus population had no influence on food preferences. However, the preferences differed between adults and the third instar larvae. The adults preferred seeds of Robinia pseudacacia followed by Althaea officinalis, while the preferences of larvae were less pronounced and ranked in order Althaea officinalis, Robinia pseudacacia, and Tilia platyphyllos. Existence of trophic populations of P. apterus was not confirmed by our experiment. Durations of feeding were longer on preferred species of seeds in both adults and larvae. and Marta Kristenová, Alice Exnerová, Pavel Štys.
Larvae of the butterfly, Battus polydamas archidamas (Papilionidae: Troidini) feed exclusively on aristolochic acid (AAs)-containing Aristolochia species (Aristolochiaceae). The distribution of sequestrated AAs in the tissues (body, integument and osmeterial secretions) of B. polydamas archidamas larvae during their development, when fed on a meridic diet containing either a higher or lower concentration of AAs (AAI and AAII) than occurs naturally in the aerial tissues of their host plant, was determined. Accumulation of AAs in the body and integument was proportional to the weight of larvae and greater in the larvae that fed on the diet containing the higher concentration of AAs. Phenolic AAs (AAIa and AAIVa) not present in the diets were found in all larval tissues examined. Integument and body extracts had a higher AAI/AAII ratio than in the original diet and also a relatively high AAIa/AAIVa ratio, suggesting a preferred AAII to AAIa transformation in those larval tissues. In the osmeterial secretion, the value of the AAI/AAII ratio was similar to that in the diets and the AAIa/AAIVa ratio close to 1, which suggests that hydroxylation of AAI to AAIVa and of AAII to AAIa occur to similar extents. The higher accumulation of AAs and the relatively higher proportion of AAI, one of the most toxic AAs, in the integument, suggest that their role is to deter attacks by natural enemies. and Carlos F. PINTO, Alejandro URZÚA, Hermann M. NIEMEYER.
Hmyz sající krev svých hostitelů často přenáší i původce různých, více či méně závažných onemocnění, čímž představuje hrozbu, ale současně poskytuje dokonalou ukázku biologické adaptace a evolučního závodu s obranou hostitele i s triky přenášených patogenů. Článek stručně představuje vybrané zástupce krevsajícího hmyzu (např. blechy, vši, ovády, kloše, štěnice, komáry) z území České republiky i vyskytující se v různých částech světa, jejich způsob života a jimi přenášené původce onemocnění., Insects sucking the blood of their hosts often transmit the agents of various serious diseases, which pose a threat, but which at the same time provide a perfect example of biological adaptation and the endless evolutionary race against the host's defences with tricks involving transmitted pathogens. This article briefly presents some selected representatives from these blood-sucking insects (e.g. fleas, lice, horseflies, bedbugs, keds and mosquitoes) in the Czech Republic and occurring elsewhere in various parts of the world, their way of life and the aetiological agents which they transmit., and Jan Votýpka.
The correlation between dorsal wing colours and spectral sensitivity of the compound eyes of 13 species of thecline butterflies, consisting of 8 sexually monomorphic and 5 dimorphic species, was investigated. Spectral reflectance of the dorsal surfaces of the wings was measured using a spectrophotometer and spectral sensitivities using electroretinography. All 13 species examined showed a common basic pattern of spectral sensitivity with a primary peak at a wavelength of 440–460 nm. Detailed analyses of the deviations in sensitivity from the basic pattern revealed a correlation in monomorphic species with conspicuous wing hues, especially in males., Michio Imafuku., and Obsahuje seznam literatury
Ants are the most abundant group of soil arthropods in olive groves where they are involved in various trophic relationships of great importance for crops. The system of soil management is one agricultural practice that has a great effect on ants, so the objective of this study was to compare ant populations in organic olive orchards with a ground cover of natural vegetation and others where this natural vegetation is mechanically removed at the beginning of June. Ants were sampled using pitfall traps at 14, 30, 70 and 90 days after the removal of the ground vegetation. Overall, ant biodiversity did not change. However, changes were observed in the abundance of ant species, in particular, in those species that build shallow nests in the soil, both between the rows of trees and under the canopy of olive trees. In contrast, deep nesting species, such as Messor barbarus, were not affected. The response also differed between the various genera: the abundance of Cataglyphis increased, due to there being more of the species C. rosenhaueri, while there was a significant fall in Aphaenogaster, due to the decline in abundance of A. senilis. Thirty days after the removal of vegetation, the response of most of the genera was clearly noticeable, due to the increased activity of workers, and in some cases there were still differences after 90 days. and Mercedes Campos, Luisa Fernández, Francisca Ruano, Belén Cotes, Manuel Cárdenas, Juan Castro.
Some ethological aspects of the interrelations between ants and the larvae of Blasticotoma filiceti Klug, 1834 were investigated in the Altai Republic and Novosibirsk Region in 2006-2008. The interactions of ants with the larvae of this sawfly are determined by the concealed way of life style of B. filiceti. The majority of the ant-sawfly encounters occurred near holes in fern fronds at the moment when larvae excreted liquid or left their tunnels before descending to the soil prior to overwintering. Sawfly larvae visited by more aggressive ants, such as Formica s. str., leave the fern fronds slowly, which enables them to avoid inciting attacks by ants. The behaviour of the ants while collecting the larval excretion is similar to their behaviour at sugar troughs. The organisation of the collecting larval excreta by ants was investigated in detail in the cases of Formica polyctena Förster, 1850 and Myrmica rubra Linnaeus, 1758. The individual fern plants with sawfly larvae are attended by relatively constant groups of foragers in both cases. However, the highly social red wood ants interact with sawfly larvae in a more complex way. While the working groups of M. rubra tending sawfly larvae consist only of non-aggressive "unspecialized" foragers, those of F. polyctena include also a few "on duty" ants that protect the trophobionts, at least from the other ants. and Tatiana A. NOVGORODOVA, Olga B. BIRYUKOVA.
The factors that affect oviposition and consequently spatial distribution of the galls of many gall makers are poorly understood. Knowledge of these factors could result in a better understanding of the mechanisms that initiate and regulate the development of galls. We tested the hypotheses that, regardless of tree height, galls of Cynips quercusfolii L. produced agamically are distributed randomly in the crowns and on the veins of leaves of oak trees. This study was done in Poland on 15 pedunculate oak (Quercus robur) trees of various heights. We measured the areas of 1659 leaves, including 192 leaves with galls, and the distances along a vein from a gall to the petiole and from gall to leaf edge. The number of galls did not depend on tree height but depended on the position of the leaf within the crown (upper or lower). Regardless of the position in the crown, leaves with galls were significantly larger than those without galls. We conclude that galls were located at a fixed distance from the edge of leaves irrespective of leaf size, but the distance from the gall to the leaf petiole depended significantly on leaf size. We conclude that agamic females of C. quercusfolii prefer large leaves and choose the site on a leaf on which to deposit their eggs. This probably ensures that the developing gall obtains the required amount of nutrients and assimilates., Marian J. Giertych, Andrzej M. Jagodzinski, Piotr Karolevski., and Obsahuje seznam literatury