The Hemiptera (Insecta) communities of tropical rain forest in Sulawesi

The structure and composition of Hemiptera communities of tropical rain forest in Dumoga-Bone National Park, Sulawesi, Indonesia were investigated over a 1-year period. The aim was to investigate the extent to which insect samples, obtained using six different techniques, were representative of the whole community, and to explore temporal and spatial variation in Hemiptera community composition. Sampling techniques employed were Rothamsted light trapping, canopy fogging, malaise trapping at both ground and canopy level, flight interception trapping and yellow water pan trapping. Overlap between faunas collected using different techniques was surprisingly low emphasizing the limitations of using any single method to sample and thereby describe the Hemiptera community. Differences were observed at the species, family and suborder levels. Similarly, there were major differences in faunal composition between sites and diversity appeared to peak at elevations between 600–1000 m. Seasonal changes were also significant but generally lower than between methods or sites. Results are discussed in relation to factors such as food availability and host specialization and the efficacy of each sampling method is reviewed in relation to the biology of the different Hemiptera groups and the composition of the samples obtained.     

Foraging behaviour influences the outcome of predator–predator interactions

Abstract.  1. Interactions among predators may influence the total efficiency of a predator complex. The effect of intra- and interspecific interactions of the generalist predators Orthotylus marginalis (Heteroptera: Miridae) and Anthocoris nemorum (Heteroptera: Anthocoridae) was investigated in a laboratory experiment. Outcomes of the interactions were determined by comparing predation rates on eggs and larvae of the blue willow beetle Phratora vulgatissima of single individuals with those of two individuals of the same or different species.
2. A non-additive, antagonistic effect on predation rates due to intraspecific interactions was found between individuals of A. nemorum . No such effect was found in O. marginalis . These results are as expected as a consequence of differences in behaviour of the two predator species: A. nemorum is a much more active and mobile predator than O. marginalis .
3. Contrary to expectation, interspecific interactions between A. nemorum and O. marginalis did not affect the total predation rate.
4. An observation from the field corroborated the results obtained in the laboratory study; there was no negative relationship between the densities of the two predator species, indicating that the two species do not interact negatively in the field at their natural densities.
5. It is concluded that the additive effect of multiple predator species is of potential value in biological control.     

Relative impacts of mortality factors in field populations of the waterstrider Gerris buenoi Kirkaldy (Heteroptera: Gerridae)

Summary Impacts of predators, food levels and cannibalism on population growth of G. buenoi were studied in two experiments using field exclosures. In the first experiment, experiments using field exclosures. In the first experiment, impacts of (1) predation by freshwater invertebrates and (2) food limitation on gerrid populations were considered in a 2 x 2 factorial design, using food supplements and elimination of predators as the experimental treatments. In the second experiment, the possible contribution of intraspecific predation to fitness of gerrid cannibals was assessed.Presence of invertebrate predators decreased egg-adult survivorship 2–3 fold and decreased the range of juvenile development times. The main predators noted in this study were fishing spiders (Dolomedes), backswimmers (Notonecta), larvae of predaceous diving beetles (Dytiscus), and dragonfly naiads (Aeshna). Food supplements, at 50–200% (by weight) of average natural surface fall, did not significantly effect survivorship but were associated with decreases in mean development time and with increases in whole body dry mass of teneral adults. Increases were greater for females than for males, suggesting that females are more likely to be protein limited under field conditions. Absence of predators was associated with smaller body size among teneral adults of G. buenoi, suggesting that screening out aquatic predators also had significant impact on food available to semi-aquatic bugs.Results of the second experiment demonstrate that the food cache hypothesis (Polis 1980) does not hold for G. buenoi. Neither survival to the adult stage nor dry mass of teneral males differed significantly between groups with or without access to early stages as potential prey. Dry mass of teneral females with access to younger stages during their own development was significantly less than for those without access to gerrid prey, suggesting that competition among stages for food was more important than cannibalism in, this experiment.A more comprehensive version of a paper presented at the XVII Int Cong Entomol, Hamburg, Federal Republic of Germany as part of a symposium entitled Phylogeny, Bionomics and Ecology of Waterstriders (Hemiptera, Gerridae)     

The effects of mating,exogenous juvenile hormone and a juvenile hormone analogue on pheromone titre,calling and oviposition in the omnivorous leafroller moth (Platynota stultana)

Mating in Platynota stultana resulted in the termination of calling, the gradual reduction of pheromone in the pheromone glands to non-detectable levels (<0.1 ng/♀) within 14 h, and oviposition of the first batch of eggs 20–24 h after copulation. Decapitation of virgin females resulted in a similar decline in pheromone titre, and also eliminated oviposition and calling. Pheromone production appears to be controlled via the head. Mating probably terminates neural or hormonal input required for pheromone production and/or removes neural or hormonal inhibition of pheromone degradation. A juvenile hormone analogue (ZR-512) and juvenile hormones I, II and III applied exogenously to virgin females elicited oviposition comparable to mated females and terminated calling within 48 h. The juvenile hormone analogue also appeared to block pheromone production in virgin females. These results suggest that juvenile hormone may be involved in the switch from virgin to mated behaviour in this species.     

云南壮异蝽属及娇异蝽属新种记述(半翅目:异蝽科)

云南地区的壮异蝽属(Urochela Dallas)和娇异蝽属(Hrostylis Westwood)截止到目前共记录23种。本文记述了在该省西部地区发现的5新种,现描述如下。模式标本保存于天津南开大学生物系。 钩壮异蝽Urochela hamata,新种(图1,2) 体黄褐色,具黑褐色花斑及黑色刻点。触角第4节中部及第5节基半部为淡黄色;     

Nutrition et élevage du prédateur polyphageMacrolophus caliginosus [Heteroptera,Miridae] sur milieux artificiels

La possibilité de nourrir la punaiseMacrolophus caliginosus Wagner à l'aide de milieux artificiels a été testée. En l'absence de végétal, les témoins nourris avec des ?ufs d'Ephestia kuehniella Zeller ont une survie médiocre et fournisent 33% d'adultes. Avec le meilleur milieu artificiel la survie est comparable à celle des témoins et 21 % d'adultes sont obtenus. Avec ce même milieu, mais en présence de feuille de géranium, la production d'adultes atteint 62%. Les compositions en acides aminés des punaises élevées avec le milieu montrent des écarts inférieurs à 20% par rapport aux témoins. Le développement complet deM. caliginosus nourri à l'aide de milieu artificiel a été obtenu. Le végétal joue un rôle important dans la biologie de ce prédateur.     

Ontogenetic change in effectiveness of chemical defence against different predators in Oxycarenus true bugs

Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa – spiders and birds – to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators.     

Oviposition preference of Anthocoris nemorum and A. nemoralis for apple and pear

Anthocoris nemorum L. and Anthocoris nemoralis Fabricius (Heteroptera: Anthocoridae) are important predators of insect pests in pome fruit. Females insert their eggs in leaf tissue. The females’ choice of oviposition site is important for the subsequent distribution of nymphs on host plants. Oviposition preference for apple and pear leaves was tested in the laboratory in four experiments (experiments 1–4). In three experiments it was tested whether simulated insect damage to leaves (experiments 5 and 6) or the presence of prey (experiment 7) influenced oviposition preference. The effect of the presence of prey was only tested for A. nemorum on apple leaves. There was a highly significant anthocorid species × plant interaction for the number of eggs laid on apple and pear leaves. Anthocoris nemorum laid more eggs on apple than on pear leaves, while A. nemoralis preferred pear. Anthocoris nemorum's preference for apple increased over the 6‐week period in which experiments 1–4 were performed, from 66% to 91% eggs laid on apple leaves. No change over time in preference was found for A. nemoralis. Across experiments 1–4, the majority of A. nemorum eggs were laid near leaf margins, whereas eggs of A. nemoralis were more commonly found in the leaf centre, 5 mm or more from the margin, with a highly significant leaf region × species interaction. There was no significant difference in preference for leaf side between A. nemorum and A. nemoralis, but there was a highly significant plant × leaf side × experiment interaction. Thus, more eggs were laid on the ventral than on the dorsal side of pear leaves in experiment 4, while significantly more eggs were laid on the dorsal side of apple leaves in experiments 3 and 4. Choice tests between damaged and healthy leaves showed that A. nemorum laid significantly more eggs on the damaged leaves, while A. nemoralis preferred healthy leaves. Anthocoris nemorum showed a near‐significant preference for ovipositing on leaves with eggs of Operophtera brumata (Lepidoptera: Geometridae). The oviposition preferences found correspond to the natural distribution of these predators in apple and pear orchards. The preference of A. nemorum for leaf margins, and of A. nemoralis for the leaf centre as an oviposition site, supports earlier observations. A preference for leaf side for oviposition site has not been reported earlier. Preference for damaged leaves could help A. nemorum to locate prey in a field situation.     

Plant preference in relation to life history traits in the zoophytophagous predator Dicyphus hesperus

Dicyphus hesperus Knight (Heteroptera: Miridae) is an omnivorous predator used to control pests of greenhouse vegetables. Plant preferences and life history traits were studied using nine plant species: Lycopersicon esculentum Mill. (Solanaceae), Capsicum annuum L. (Solanaceae), Verbascum thapsus L. (Scrophulariaceae), Nepeta cataria L. (Lamiaceae), Stachys albotomentosa (Lamiaceae), Nicotiana tabacum L. (Solanaceae), Vicia sativa L. (Fabaceae), Zea mays L. (Gramineae), and Chrysanthemum coronarium L. (Asteraceae). Plants were selected from among potential target crops, natural hosts, plants used for mass rearing, and plants on which D. hesperus has not been reported. Plant preference was measured by multi‐choice host plant selection and oviposition assays. Development and reproduction were measured on each of the plant species on both a plant diet alone and on a plant diet supplemented with Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. Dicyphus hesperus females and nymphs expressed a preference for some plants over others. Plant preference ranged from low preference plants, such as Z. mays, V. sativa, C. coronarium, and C. annuum, to high preference plants such as V. thapsus, N. tabacum, and S. albotomentosa. When E. kuehniella eggs were supplied, there were few differences in the development time and fecundity of D. hesperus among plants, with the exception of corn and broad bean, where fecundity was lower. On a plant diet alone, nymphs were able to complete their development on V. thapsus, C. annuum, and N. cataria. However, mortality and development time were much lower on V. thapsus than on C. annuum and N. cataria. On most of the plant species D. hesperus did not lay any eggs when fed on a plant diet alone. On V. thapsus, females laid a few eggs and lived longer than when fed on prey. Dicyphus hesperus females tended to prefer host plants on which nymph survival without prey was greatest.     

Tubular inclusions within polyploid nuclei ofGerris najas do not react with a monoclonal anti-β-tubulin antibody

Summary Variable aggregates, composed of tubules with a mean diameter of 19 nm, were found exclusively within polyploid nuclei of the midgut, Malpighian tubes, cyst cells, testis epithelium, and trophocytes ofGerris najas. The nuclear inclusions are always in direct contact with the nucleoplasm, and no other structures are associated with them. They appear most abundant within degenerating nuclei of the midgut surface epithelium, where they form paracrystalline bodies or spindle-shaped inclusions with tapered ends. Smaller fusiform inclusions occur in younger epithelial nuclei but not in the diploid nuclei of regenerative cells. In other tissues, mainly spindle-shaped inclusions can be observed, the longest (4.5 m) in cyst cell nuclei. The mean diameter of the tubules determined from transverse sections, resembles that of cytoplasmic microtubules and was verified statistically. The inclusions within trophocyte nuclei failed to react with monoclonal anti--tubulin antibody, although the antibodies could penetrate the nuclei after extensive lysis of the cells.