Range shifts are among the most conspicuous effects of global warming. Marked changes in distribution are recorded both for highly mobile species of insects, which are capable of flight, and wing-dimorphic species with predominantly short-winged individuals. One of these species is the bush-cricket Metrioptera roeselii, which occasionally produces long-winged individuals. However, there is little known about the locomotory behaviour of wing-dimorphic insects. Yet to be able to predict potential range shifts it is necessary to know the dispersal potential of macropters. Therefore, an experiment was conducted in which individually marked M. roeselii were released at four sites. Different movement parameters, such as daily movement, activity radius, dispersal range, net displacement and crowding rate, were calculated. The statistical analyses showed that the movement of long-winged and short-winged individuals did not differ, but the percentage of individuals that were not seen again was twice as high for long-winged bush-crickets. These results suggest that most of the long-winged individuals that were seen again did not fly; i.e., they had the same basic mobility as the short-winged individuals. However, the comparatively low number of long-winged individuals that were seen again suggests that at least some macropters are long-distance dispersers, which is relevant for the dispersal process. The comparison of sexes showed that males were significantly more mobile than females. This sex-specific locomotory behaviour in M. roeselii might depend on a complex series of social interactions and physiological conditions. and Dominik Poniatowski, Thomas Fartmann.
A new genus and species of Hemiptera: Heteroptera: Enicocephalomorpha: Aenictopecheidae: Aenictopecheinae, Ulugurocoris grebennikovi gen. et sp. n., based on micropterous females from Tanzania, Uluguru Mts, Budunki, is described and differentiated. The males are probably macropterous. Some general aspects of morphology of U. grebennikovi are discussed in a broader context, such as presence of cephalic trichobothria (suggested to be a groundplan character of Heteroptera), presence of “gular sulci” (suggested to have an ecdysial function), lack of cephalic neck (symplesiomorphy with other Hemiptera), presence of posterior lobe of pronotum associated with the epimeroid (a new term for so called “proepimeral lobe”), and presence of notopleural sulcus on the propleuron. Diagnostic characters of the Aenictopecheinae are summarized and distribution of their seven genera is reviewed. Ulugurocoris grebennikovi is the first representative of the basal family Aenictopecheidae in the Afrotropical Region. The type locality is situated in the Eastern Arc Mountains (Tanzania), a recently identified hotspot of Afrotropical diversity characterized by a high degree of endemism caused by high rates of speciation combined with low rates of extinction. A brief characterization of the area is provided., Pavel Štys, Petr Baňař., and Obsahuje seznam literatury
Velia currens (Fabricius, 1794) and V. gridellii Tamanini, 1947 are two South European species of Veliidae, whose ecology and behaviour are poorly known. The aims of this study were to investigate their life histories, quantify occurrence of wing polymorphism and gather information on their degree of co-occurrence. Nine different populations were regularly surveyed from April to November 2010. Furthermore, a dataset containing information on the occurrence of the two species and the presence of winged morphs at 294 sites was compiled from museum collections, private collections and published literature. No evidence for multivoltinism was detected in either species. However, oviposition and and/or hatching were protracted in time so that early-instar nymphs and adults co-occurred up to midsummer. Although their distributional ranges completely overlap at a large spatial scale, the two species co-occurred only rarely at the same sites and the degree of co-occurrence was lower than expected by chance. Winged specimens were rarely recorded. At least in V. gridellii, the numbers of winged individuals were inversely related to the altitudes of the sites. During the summer, when some of the streams surveyed dried up, several specimens were found in an apparent state of lethargy, under stones. It is hypothesized that the ability to aestivate, coupled with the ability to walk from one site to another may reduce the advantage associated with producing winged forms and account for the low rate of occurrence of macropterism in these species., Fabio Cianferoni and Giacomo Santini., and Obsahuje seznam literatury
Results of studies on prey suitability for generalist predators are important for efficient mass rearing and implementing Integrated Pest Management Programmes (IPM). The green lacewing, Chrysoperla sinica (Tjeder), is a polyphagous natural enemy attacking several pests on various crops in China. We investigated the effect of feeding it different species of prey on its pre-imaginal development, survival, adult longevity and fecundity under laboratory conditions. The prey species tested were nymphs of Aphis glycines Matsumura, cotton aphid Aphis gossypii Glover, peach aphid Myzus persicae Sulzer, corn aphid Rhopalosiphum maidis Fitch and cowpea aphid Aphis craccivora Koch, and eggs of the rice grain moth, Corcyra cephalonica Stainin. None of these species of prey affected the pre-imaginal survival or percentage survival of the eggs of the predator. However, eggs of C. cephalonica and nymphs of M. persicae and A. glycines were the best of the prey species tested, in that when fed on these species the pre-imaginal developmental period of C. sinica was shorter and its adult longevity, fecundity and percentage survival greater than when fed the other species of prey. In contrast, when fed nymphs of A. craccivora the pre-imaginal development period was longer, adult longevity shorter and fecundity lower. These findings could be helpful in defining more optimum conditions for the mass rearing of C. sinica for use in integrated pest management (IPM) programmes for various crops., Niaz Hussain Khuhro ... [et al.]., and Obsahuje seznam literatury
Age of host eggs can be a limiting factor for egg parasitoids. It is expected that old eggs are less preferred by egg parasitoids, which can discriminate between eggs of different ages by using chemical cues. The objective of this study was to determine the preference, development and arrestment of Telenomus remus Nixon (Hymenoptera: Scelionidae) parasitizing Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) eggs of different ages. This egg parasitoid preferred to parasitize 1- and 2-day-old eggs rather than 3-day-old eggs in choice and no-choice assays. However, although the percentage emergence of parasitoids is significantly lower from 2- and 3-day-old eggs, the sex ratio and developmental time are unaffected. Parasitoids spent longer searching substrates impregnated with extracts of 1- and 2-day old eggs than 3-day-old eggs. Our results reveal that T. remus is able to distinguish the most suitable (1-day-old) from the least suitable (3-day-old) host eggs, but unable to recognize the unsuitability of intermediate aged eggs. Egg arrestants may be responsible for the preference of T. remus for ovipositing in 1- and 2-day old eggs., Maria Fernanda Gomes Villalba Penaflor ... [et al.]., and Obsahuje seznam literatury
The effect of different host plants on Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) body size was investigated. Thrips from three different populations, from the Netherlands, Italy, and USA, achieved greater body sizes when reared on cucumber than on bean. The same thrips grew larger when reared on susceptible than on resistant cucumber. On the latter, reproduction was reduced, suggesting that smaller thrips have a lower reproduction. However, no evidence was found for a correlation between size and reproduction in experiments with thrips from four different populations, from the Netherlands, New Zealand, France, and USA that differed significantly in body size. Also when individual thrips from the four populations were tested, there was no correlation between size and reproduction. It is concluded that resistant cucumber affects both size and reproduction of F. occidentalis. However, lower reproduction in general is not associated with smaller body size., Willem Jan de Kogel, Domenico Bosco, Marieke van der Hoek, Chris Mollema, and Lit
Although the effects of host plant quality on the performance of polyphagous herbivores are largely uniform across insect taxa, there are various exceptions to this rule. In particular, there are scattered reports of cases in which the relative quality of different hosts differs among larval instars of a single insect species. Such cases are explained either in terms of differences in the susceptibility of different aged larvae to plant defences or, alternatively, age-specific nutritional demands. Here we report the results of experiments that show that young larvae of the polyphagous common heath moth Ematurga atomaria (Lepidoptera: Geometridae) consistently attain higher weights on common heather Calluna vulgaris than bilberry Vaccinium myrtillus, whereas the rank order of these host plants is reversed in the final larval instar. Phytochemical analyses showed that differences in nutrient content of these plants are not likely to explain the observed pattern. Instead, the results are more consistent with the idea that the greater chemical defence of bilberry has a relatively stronger influence on young than old larvae., Helen Vellau, Siiri-Lii Sandre, Toomas Tammaru., and Seznam literatury
a1_There is little systematic research on the effect of transgenic maize expressing Bacillus thuringiensis (Bt) toxins on insect survival and the response in vivo of their detoxification enzymes. Results of laboratory bioassays indicate that the whorl leaves of transgenic maize lines G03-2396 and G03-2739 significantly affected the survival of neonate and third instar larvae of the Asian corn borer, Ostrinia furnacalis (Güenée). Neonate mortality two days after being fed on G03-2739 was 72.5% and exceeded 92.5% four days later. The percentage mortality of third instar larvae six days after being fed whorl leaves from G03-2396 exceeded 65%. The resistance of whorl leaves to insect attack was greater than that of maize-ears, but less effective against attacks by third instar larvae. Neonate development was more prolonged when they were fed on whorl leaves of both the transgenic maize lines. In contrast, low pupation (<80% of that recorded in the controls), ecolosion and fecundity were recorded following ingestion of maize-ears, with pupal weights 10-14 mg lower than that of controls. The growth rates of third instar larvae recorded three and six days after feeding on whorl leaves were lower, but food utilization, conversion and relative metabolism were not significantly affected. Relative food ingestion, relative growth rate and other nutritional indicators of third instar larvae were significantly lower six days after the ingestion of ears and that of fifth instar larvae after three days. In vivo activity of carboxylesterase was decreased to a greater degree after three days when the larvae were fed on whorl leaves than ears, with no significant effect on fifth instar larvae. Furthermore, in vivo activity of glutathione S-transferase (GST) of third instar larvae was significantly affected following the ingestion of whorl leaves. These results are discussed in the context of the literature on the resistance, a2_of transgenic plants and of improving the resistance of plants to attack by the different larval stages of insects., and Min Juan Shi, Pei Ling Lu, Xiao Li Shi, Yi Zhong Yang.
The occurrence of melatonin is known in nearly all organisms, but nothing is known exactly about its function outside of vertebrates. Long-term perifusions as well as short-term batch incubations of brains and moulting glands of the cockroach Periplaneta americana were used to identify the effect of melatonin on the release of prothoracicotropic hormone, a glandotropic neuropeptide in the brain, which stimulates the production of the moulting hormone ecdysone in the moulting gland. This is the first experimental evidence of a neurohormonal releasing effect of melatonin in the insect nervous system., Klaus Richter, Elmar Peschke, Dorothee Peschke, and Lit
Reduced oviposition by ladybirds in the presence of tracks of fourth instar larvae owing to the presence of oviposition deterring pheromones is well established across many genera. However, deterrence, if any, by other life stages has not been well investigated, in particular the effect of conspecific presence. The present study investigates the effects of conspecific presence and semiochemicals of conspecific life stages (eggs, fourth instar larvae, pupae, adult males and females) on oviposition by five ladybird (Coleoptera: Coccinellidae) species, viz. Coccinella septempunctata, Coccinella transversalis, Cheilomenes sexmaculata, Propylea dissecta and Anegleis cardoni. Results reveal that the presence of life stages inhibits oviposition and the inhibition is density-dependent, although the degree of inhibition is species-specific. Surface semiochemicals of eggs and larval and adult tracks also show density-dependent inhibitory effects. Moreover, the semiochemicals in tracks (oviposition deterring pheromones) and egg surface semiochemicals are not similar, indicating semiochemical parsimony. Of all species tested, C. transversalis and C. septempunctata were the most and the least responsive to both conspecific presence and semiochemicals, respectively., Geetanjali Mishra ... [et al.]., and Obsahuje seznam literatury