Anthocoris Nemorum Research Articles

Development and emergence of Sitotroga cerealella (oliver) on stored yellow maize genotypes as affected by physical factors and grain quality

Angoumois Grain Moth, Sitotroga cerealella (Olivier) (Lepidoptera:Gelechiidae) is a serious primary pest of stored grain in many parts of the world. A study was carried out in the laboratory to investigate the effects of grain physical and intrinsic properties, temperature, relative humidity, and grain moisture content on the development and emergence of S. cerealella. The experiment was arranged in completely randomized design with three replicates for each maize genotypes used. Daily temperatures and relative humidity were recorded at 8:00 and 16:00 GMT with a Temperature and Humidity Sensor, which was embedded in the polypropylene bag containing six maize genotypes and tied after each reading to prevent emerging insects from escaping. The number of S. cerealella that emerged was observed weekly. Angoumois grain moth emergence on stored husked maize ears began in the 3rd week through to the 6th week in storage. The moth emergence was higher in the season with higher percentage grain moisture content. A significant (P<0.05) difference was observed in percentage grain moisture within almost all the same genotypes during both major and minor seasons. Aburokokoo, Ahoodzin, and Obatanpa had significantly (P<0.05) higher mean numbers of the emerged moth from the 4th to 6th week. The grain physical and intrinsic characteristics such as surface area and weight of Aburokokoo, Ahoodzin, and Obatanpa were statistically different (P<0.05) from the other three genotypes. A significant positive relationship was observed between grain surface area, grain weight, density and total S. cerealella emerged. Abontem, Honampa, and GH2354 with smaller grain surface area and lower grain weight had smaller mean number of the moth emerging. Anthocoris nemorum (L.) an important generalist agricultural pest predator was observed to be associated with the moth when its population was high (13-63) but none when the moth population was very small (0-4) in store. The association between mean daily temperatures and relative humidity during the 6 weeks storage in both seasons was inversely proportional. About 88.25% of the variation in relative humidity depends on temperature. Key words: Maize, insect pest, grain hardness, predator, Anthocoris nemorum

<i>Anthocoris nemorum</i> (Heteroptera: Anthocoridae) as predator of cabbage pests – voracity and prey preference

Laboratory experimentswere performed with adult female Anthocoris nemorum (Linnaeus) (Heteroptera: Anthocoridae) at 20°C ± 1°C, L16:D8, 60–70% RH to determine voracity and preference on cabbage aphids (Brevicoryne brassicae L.) (Hemiptera: Aphididae), diamondback moth larvae (Plutella xylostella L.) (Lepidoptera: Plutellidae) and Western flower thrips (Frankliniella occidentalis Pergande) (Thysanoptera: Thripidae) (model species for cabbage thrips (Thrips angusticeps Uzel) (Thysanoptera: Thripidae)). When offered individually, A. nemorum readily accepted all three species with no significant differences in consumption. When aphids and moth larvae were offered simultaneously, A. nemorum showed preference for the latter (numbers eaten and biomass consumed). When aphids and thrips were offered together, A. nemorum preferred thrips in terms of numbers eaten but preferred aphids in terms of biomass consumed. The results showed that A. nemorum is a voracious predator of B. brassicae, P. xylostella and F. occidentalis and can therefore be considered as a potential candidate for biological control in cabbage.

Generalist predator contributions to the control of Tetranychus urticae in strawberry crops documented by PCR-based gut content analysis.

The contribution of generalist insect predators to the control of the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), an herbivorous pest of many crops, is poorly understood. One of the common insect predators in strawberries is the generalist predatory bug Anthocoris nemorum L. (Hemiptera: Anthocoridae), which has the potential to contribute to the control of pest populations. The feeding of adult A. nemorum on T. urticae was assessed by sampling individuals from an organic strawberry field in Denmark, and using PCR gut content analysis to detect remains of T. urticae within their gut. In the lab, we assessed that the DNA half-life detectability was 21.5h. Significant numbers of field-collected A. nemorum tested positive for T. urticae prey DNA, with very high numbers in June (62.8%) and August (38.8%). This study presents conclusive evidence that the generalist predator A. nemorum can contribute to the decrease of T. urticae densities in strawberry fields, although the actual contribution in the present study is probably limited because predator populations were relatively low compared to T. urticae. The abundance of T. urticae did not increase significantly during the period of sampling, suggesting that a complex of natural enemies can achieve biological control of T. urticae in protected strawberries.

Plant sex effects on insect herbivores and biological control in a Short Rotation Coppice willow

In the wild, plant sex can affect plant-herbivore interactions and higher trophic levels, including natural enemies of the herbivores. However, the possibility of manipulating plant sex to improve biological control and reduce herbivory in domesticated dioecious crops remains unexplored. The dioecious bioenergy crop, Salix viminalis, is often planted in monoclonal, and thus monosexual, fields. We investigated whether using plant clones of either sex, or mixing plants of both sexes, reduced the performance and abundance of the herbivorous pest insect Phratora vulgatissima and its main natural enemy, Anthocoris nemorum, and whether predation was affected. The herbivore laid more eggs, and the predator survived longer, on female plants in the lab. However, these effects did not translate into differences in predation rates in laboratory experiments or differential insect abundances on plants of either sex or plantation sex composition in the field. Plant genotype did have a significant effect on insect abundances, but this was due to plant traits other than sex. The results indicate that manipulating plant sex will not lead to improved biological control or reduced insect herbivory in S. viminalis energy forestry, but suggest that a focus on plant genotypic differences offers promise for improving management practices.

Predator hunting mode and host plant quality shape attack‐abatement patterns of predation risk in an insect herbivore

AbstractGroup formation reduces individual predation risk when the proportion of prey taken per predator encounter declines faster than the increase in group encounter rate (attack‐abatement). Despite attack‐abatement being an important component of group formation ecology, several key aspects have not been empirically studied, that is, interactions with the hunting mode of the predator and how these relationships are modified by local habitat quality. In 79 cage trials, we examined individual egg predation risk in different‐sized egg clutches from the blue willow beetle Phratora vulgatissima for two predators with different hunting modes (consumption of full group [Orthotylus marginalis] vs. part group [Anthocoris nemorum]). Because these predators also take nutrients from plant sap, we could examine how the quality of alternative food sources (high‐ vs. low‐quality host plant sap) influenced attack‐abatement patterns in the presence of different hunting strategies. For the O. marginalis predator, individual egg predation risk was largely independent of group size. For A. nemorum, egg predation risk clearly declined with increasing group size. However, approximately one‐third of the grouping benefit was lost to an increase in group detectability. There were clear differences in attack‐abatement patterns between plants with high‐ vs. low‐quality sap. When O. marginalis was the predator, there was no clear change in attack‐abatement in relation to host plant quality. However, for A. nemorum there was a clear reduction in overall predation risk and a stronger attack‐abatement pattern with increasing group size when plant sap quality increased. This implies that the relative benefits of prey grouping behavior for any species might show diurnal or seasonal changes as other aspects of resource/habitat quality change for the focal predator. Modulation of attack‐abatement by bottom‐up effects such as plant‐based food resources is yet to be incorporated into general theory, despite the ubiquity of omnivorous predators and with omnivory being important for shaping food webs, ecosystem functions, and in biological control. Thus, ongoing refinement of attack‐abatement theory by focusing on bottom‐up vs. top‐down processes could have significant impacts on many important contemporary fields of study.

Plant‐sex‐biased tritrophic interactions on dioecious willow

Plant sex effects on herbivores are well studied, but little is known about these effects on predators and predator–herbivore dynamics. Here we take a holistic approach to study, simultaneously, plant sex effects on herbivore and predator preference and performance, as well as population densities and predation pressure in the field. For dioecious Salix cinerea (grey willow) we found that male plants represented higher host plant quality than females for an omnivorous predator (Anthocoris nemorum, common flower bug), while host plant quality for its herbivorous prey (Phratora vulgatissima, blue willow beetle) was not sex‐biased. The herbivore strongly preferred the host plant sex (female) that was suboptimal for the predator, which in turn followed its prey to female plants, leading to plant‐sex‐biased predation. These results provide new insight into the far‐reaching effects of plant sex on insect communities, and open up novel opportunities for improving biocontrol of the herbivore in Salix short rotation coppice.

True bugs (Hemiptera, Heteroptera) as psyllid predators (Hemiptera, Psylloidea)

Data on natural enemies of psyllids are rare and can usually be found in papers about economically significant species. During an investigation of psyllid fauna in Serbia, natural enemies were investigated, too. True bugs were the most numerous among them. From 28 psyllid species, 21 species of true bugs from families Anthocoridae and Miridae were reared. Seven species of Anthocoridae were identified: Anthocoris amplicollis (Horváth, 1839), Anthocoris confusus Reuter, 1884, Anthocoris nemoralis (Fabricius, 1794), Anthocoris nemorum (Linnaeus, 1761), Orius majusculus Reuter, 1884, Orius minutus (Linnaeus, 1758) and Orius niger Wolff, 1811. The following 14 species of Miridae were identified: Atractotomus mali Meyer-Dür, 1843, Campylomma verbasci (Meyer-Dür, 1843), Deraeocoris flavilinea (A. Costa, 1862), Deraeocoris ruber (Linnaeus, 1758), Deraeocoris lutescens (Schilling, 1836), Heterocordylus genistae (Scopoli, 1763), Hypseloecus visci (Puton, 1888), Malacocoris chlorizans Panzer, 1794, Miris striatus (Linnaeus, 1758), Orthotylus marginalis Reuter, 1884, Psallus assimilis Stichel, 1956, Psallus quercus Kirschbaum, 1856, Psallus flavellus Stichel, 1933 and Pseudoloxops coccinea (Meyer-Dür, 1843). The aim of the research was to provide list of true bugs recorded as predators of psyllids in order to preserve their diversity and significance, especially on cultivated plants.

Constitutive and herbivore-induced systemic volatiles differentially attract an omnivorous biocontrol agent to contrasting Salix clones

While carnivores are known to be attracted to herbivore-induced plant volatiles, little is known about how such volatiles may affect the behaviour of omnivorous predators that may use both plants and herbivores as food. Here, we examine how systemically produced plant volatiles, in response to local herbivore damage, differentially attract a key omnivorous predator, Anthocoris nemorum (Heteroptera: Anthocoridae), to single clones of three species of Salix: S. viminalis, S. dasyclados and S. cinerea. The profiles of the plant volatiles produced were found to vary among Salix clones and between herbivore-damaged and intact plants. Anthocoris nemorum was attracted to the volatiles released from undamaged plants of all three species, but most strongly to a native S. cinerea clone. Plants damaged by the herbivorous leaf beetle Phratora vulgatissima (Coleoptera: Chrysomelidae) were generally more attractive than undamaged plants, with A. nemorum responding to systemic changes in the damaged plants where the experimental design specifically excluded volatiles released from the actual site of damage. When comparing damaged plants, the S. dasyclados clone was more attractive to A. nemorum than the S. viminalis clone-a somewhat surprising result since this Salix clone is considered relatively resistant to P. vulgatissima, and hence offers a limited amount of prey. Our experiments highlight that both constitutive and induced plant volatiles play a role in omnivore attraction, and this emphasizes the importance of considering odours of released volatiles when cropping and breeding Salix for increased resistance to herbivores.

Biogeographical Origin and Speciation of theAnthocoris nemorumGroup

The Anthocoris nemorum group belongs to the Anthocoridae (Hemiptera), and is an important group of predators of agricultural pests. A phylogeny was constructed in conjunction with dispersal-vicariance analysis of the Anthocoris nemorum group species in order to discern the relationships between the phylogeographical structuring of A. nemorum group species, and the effects of the Qinghai-Tibet plateau uplift. The divergence times were estimated using Bayesian inference as implemented in BEAST. A portion of the mitochondrial COI gene (1406 bp) and 16S rDNA (932 bp) were chosen as molecular markers to reconstruct evolutionary relationships among 10 species in this group. The combined approach, based on phylogeny, estimation of node dates, and dispersal-vicariance analyses, indicated that the phylogeographical structuring of A. nemorum has been primarily shaped by the two main periods of the Qinghai-Tibet plateau uplift. The DIVA optimal reconstructions suggest that A. nemorum diversified from the Miocene to the Pleistocene from a center of origin in the Hengduan Mountains. The rapid uplift of Mountain ranges associated with the uplift of the entire Qinghai-Tibet plateau may have promoted rapid divergence in the A. nemorum group. Vicariance and dispersal were both essential in shaping the present distribution patterns of A. nemorum.

Plant defence: Feeding your bodyguards can be counter-productive

Insect predators often utilize plant cues to locate herbivores and plant food for sustenance when prey is scarce. The capacity of many plants to attract and support predators has sometimes been interpreted as an indirect plant defence system, which has evolved because it reduces the plants’ exposure to detrimental herbivores. In accordance with this hypothesis, plant breeders have begun to select for crop varieties that attract and support biocontrol agents. We have tested whether predator proneness to consume herbivores is affected by variation in the plant food quality provided by different Salix (willow) varieties. Plant suitability as food for the important biocontrol agent Anthocoris nemorum (Common Flower Bug) varied widely between the tested Salix varieties. The proneness of Anthocoris to consume eggs of the detrimental herbivore Phratora vulgatissima also varied between the varieties, consuming eggs at much lower rates on those that provided high quality plant food. The results suggest that plants that provide too good plant food may satiate their “bodyguards”, thereby reducing their motivation to hunt for herbivorous prey. Thus, the capacity of plants to support predators may sometimes result in a partially enemy-free space for herbivores – an outcome conflicting with the notion of “indirect defence”.

Spatial distribution of interacting insect predators: Possible roles of intraguild predation and the surrounding habitat

Predator foraging behaviour affects the outcome of enemy–enemy interactions. Using a combination of fieldwork and laboratory experiments, we show that intraguild predation may be important in the field distribution of generalist predators that share a common prey: the eggs (and larvae) of the leaf beetle Phratora vulgatissima, a major insect pest in coppicing willow plantations. We focused on a species from the hoverfly genus Parasyrphus (Syrphidae), which may exhibit large temporal and spatial variation in density. Predator and prey densities were quantified in 40 field plots in willow plantations. The likelihood of finding hoverfly eggs declined with increasing densities of two predatory mirids, Orthotylus marginalis and Closterotomus fulvomaculatus, which exhibit less mobile behaviour similar to that of hoverfly larvae. The density of a more mobile predatory bug species, the anthocorid Anthocoris nemorum, was not associated with hoverfly occurrence. These results corroborate the hypothesis that less mobile predators should be stronger intraguild predators than mobilepredators. Further partial support for this hypothesis was obtained in the laboratory study where individual predators were presented with clutches of P. vulgatissima eggs containing one hoverfly egg: the less mobile C. fulvomaculatus and O. marginalis tended to consume the hoverfly egg more readily than the more mobile A. nemorum. However, most individuals of all three bug species consumed the egg of the potential competitor – the syrphid – within 24 h. The field study also showed that hoverfly occurrence was positively associated with the density of their prey and with the presence of nearby forests. We conclude that intraguild predation, abundance of prey and the surrounding habitat affect the distribution of hoverflies in this system and should be considered when developing biological control methods.

Host-plant genotype mediates supply and demand of animal food in an omnivorous insect

1. Omnivorous predators can protect plants from herbivores, but may also consume plant material themselves. Omnivores and their purely herbivorous prey have previously been thought to respond similarly to host-plant quality. However, different responses of omnivores and herbivores to their shared host plants may influence the fitness, trophic identity, and population dynamics of the omnivores. 2. The aim of the present study was to show that an omnivorous heteropteran (Anthocoris nemorum L.) and two strictly herbivorous prey species respond differently to different genotypes of their shared host plant, Salix. Some plant genotypes were sub-optimal for the omnivore, although suitable for the herbivores, and vice versa. 3. The contrasting patterns of plant suitability for the omnivore and the herbivores highlight an interaction between plant genotype and omnivores' access to animal food. Plant genotypes that were sub-optimal for the omnivore when herbivores were experimentally excluded became the best host plants when herbivores were present, as in the latter situation additional prey became available. By contrast, the quality of plant genotypes that were intrinsically suitable for omnivores, did not improve when herbivores were present as these plant genotypes were intrinsically sub-optimal for herbivores, thus providing omnivores with almost no additional animal food. 4. The differential responses of omnivores and their prey to the same host-plant genotypes should allow omnivores to colonise sub-optimal host plants in their capacity as predators, and to colonise more suitable host plants in their capacity as herbivores. It may thus be difficult for Salix to escape herbivory entirely, as it will rarely be unsuitable for both omnivores and pure herbivores at the same time.

Uncoupling direct and indirect plant defences: Novel opportunities for improving crop security in willow plantations

Increased cropping security, i.e. minimized risk for detrimental stress events and hence improved yield stability, may be achieved by selecting resistant plant genotypes. However, strong direct defences against herbivores have been associated with negative effects on the natural enemies, resulting in weak indirect defences through these plant “bodyguards”. We compared the preference and performance of the most detrimental herbivore, the leaf beetle Phratora vulgatissima, and a biocontrol agent, the predatory bug Anthocoris nemorum, on four willow (Salix) genotypes used in short rotation coppicing. The biocontrol agent is omnivorous and survives on the plant in the absence of prey, without causing any apparent damage to the plant. Two of the genotypes intrinsically attracted and supported the bodyguard, and were at the same time partially capable of deterring and resisting the herbivore. In contrast, the third willow clone exhibited very limited direct and indirect resistance, while the fourth clone displayed intermediate levels of both. Thus, direct and indirect defence against herbivores need not be traded off in this system, but may be intertwined, resulting in “super plants” with higher probability of resisting detrimental herbivores, opening up novel possibilities for increased cropping security, without the use of insecticides.

Heteropteran fauna of apple orchards in South-East England

The heteropteran fauna in three apple orchards in Kent and East Sussex, England was surveyed in 2001, 2002, 2004 and 2006. As a result of intensive sampling, a total of 104 species were recorded. Ninety species were recorded in an experimental apple orchard at East Malling Research, Kent, which had replicated plots subject to different pesticide management regimes, while 43 and 38 species were recorded in two commercial organic apple orchards near Marden, Kent and Robertsbridge, East Sussex, respectively. In the canopy layer the abundant species, in decreasing order of their relative abundance, were Orius vicinus, Atractotomus mali, Anthocoris nemorum, Heterotoma planicornis, Phytocoris reuteri, Lygus rugulipennis, Phytocoris longipennis, Palomena prasina, Orthotylus marginalis, Blepharidopterus angulatus and Deraeocoris ruber . These 11 species comprised at least 80% of the total Heteroptera abundance in the canopy in each apple orchard. The composition of bug communities differed between years and between the plots subject to different insecticide regimes in the experimental orchard at East Malling. However, these differences were exceeded by the characteristic differences in species composition and relative abundances between the three different orchards.

Predators and parasitoids of Cacopsylla pyri (L.) (Hemiptera: Psyllidae) in Serbia

The presence of C. pyri and its natural enemies was studied in both treated and untreated pear orchards in Serbia from 2005 to 2009. Five parasitoid and 21 predator species were identified as present on a considerable number of sites. The following parasitoid species were found: Prionomitus mitratus (Dalman), Psyllaephagus procerus Marcet, Syrphophagus ariantes (Walker), Syrphophagus taeniatus (F?rster) and Tamarixia sp. In the study, the species Psyllaephagus procerus, Syrphophagus ariantes and Tamarixia sp. were for the first time identified as parasitoids of C. pyri and as new species in the Serbian fauna. Among the parasitoids determined, Prionomitus mitratus predominated. Of the predators, the following species in four orders were registered: Dermaptera [Forficula auricularia Linnaeus (Forficulidae)], Heteroptera [Anthocoris nemoralis (Fabricius), Anthocoris nemorum (Linnaeus), Orius (Heterorius) minutus (Linnaeus), Orius (Heterorius) niger Wolff (Anthocoridae), Campylomma verbasci (Mayer-D?r), Deraeocoris (Deraeocoris) ruber (Linnaeus) and Deraeocoris (Knightocarsus) lutescens (Schilling) (Miridae)], Neuroptera [Chrysopa pallens Rambur, Chrysoperla carnea (Stephens), Chrysopa sp. (Chrysopidae)], and Coleoptera [Coccinella septempunctata Linnaeus, Adalia bipunctata Linnaeus, Adalia decempunctata (Linnaeus), Hippodamia tredecimpunctata (Linnaeus), Hippodamia variegata (Goeze), Propylea quatuordecimpunctata (Linnaeus), Calvia (Anisocalvia) quatuordecimguttata (Linnaeus) (Coccinellidae), Cantharis rustica Fall?n, Rhagonycha fulva (Scopoli) and Rh. testacea (Linnaeus) (Cantharidae)]. Of the predators determined, 12 species were registered for the first time as predators of C. pyri in Serbia, while C. rustica, Rhagonycha fulva and Rh. testacea have so far been known neither in Serbia nor in the world as predators of pear suckers.

Seasonal development and ecology of anthocorids (Heteroptera, Anthocoridae)

Seasonal development and ecology of Anthocoridae are reviewed. Most of 500–600 species in the family are predacious or zoo-phytophagous, and a few other species are exclusively phytophagous or myrmecophilous. Some anthocorids are (and many others can potentially be) used as biological control agents in the Integrated Pest Management (IPM). Overwintering at the adult stage is typical of anthocorid bugs from the temperate zone (especially for the subfamily Anthocorinae). The known exceptions are the embryonic diapause in Tetraphleps abdulghanii, Temnostethus pusillus, and T. gracilis (Anthocorinae) and continuous development through all seasons (a homodynamic seasonal cycle) in Lyctocoris campestris and some species of Xylocoris (Lyctocorinae). In a number of species, especially in the genera Anthocoris and Orius, copulation occurs before overwintering and only females survive winter, a feature very unusual for Heteroptera and insects in general. Many anthocorid species are multivoltine in the temperate zone, producing several (up to 8 in some cases) generations per year. The number of generations typically decreases to 1 per year towards the north. Seasonal development of multivoltine species is chiefly controlled by daylength and temperature. All multivoltine anthocorids of the temperate zone studied to date have photoperiodic response of a long-day type: the females reproduce under the long-day conditions, but enter diapause under the short-day conditions. Towards the south, the photoperiodic response gradually becomes weaker: some populations do not enter diapause even under the short-day conditions, especially at higher temperatures. Termination of diapause is poorly understood in anthocorids, but a number of species require low-temperature treatment for a few weeks prior to the start of oviposition. Alary and color polymorphism are rare in the family, and they have never been shown to be seasonal or environmentally controlled. Pronounced seasonal migrations and aggregation behavior also have never been reported in Anthocoridae. Summer diapause appears to be very unusual for the family, having been reported only in Tetraphleps abdulghanii. The seasonal change of host plants, known in some populations of Anthocoris nemorum and A. nemoralis, is also a seasonal adaptation unusual for Heteroptera. Seasonality of tropical and subtropical species is poorly studied, but anthocorids developing without winter diapause are considered promising agents for the biological control of arthropod pests. Further studies of ecophysiology of Anthocoridae will optimize application and mass rearing of these predators in IPM programs.

Temperature effect on the predation rate of Anthocoris nemorum (Het.: Anthocoridae) on cabbage aphids (Hom.: Aphididae)

AbstractThe temperature‐dependent predation by Anthocoris nemorum L. (Het.: Anthocoridae) on second instar Brevicoryne brassicae L. (Hom.: Aphididae) at constant temperatures of 12, 15 and 20°C increased linearly with temperature with a mean (±SE) consumption of 6.9 (±0.8), 9.28 (±1) and 15.9 (±0.8) respectively. The estimated lower temperature threshold for predation (T0) was 6.4°C.

Predator foraging strategy influences prey population dynamics: arthropods predating a gregarious leaf beetle

We examined whether behavioural variation within an enemy complex attacking the willow leaf beetle, Phratora vulgatissima, influences the population dynamics of this gregarious prey. The most common enemies are three species of heteropteran arthropods: the two mirids Orthotylus marginalis and Closterotomus fulvomaculatus and the anthocorid Anthocoris nemorum. When attacking egg clusters on plants in the laboratory, the two mirids consumed a greater proportion of eggs within egg clusters than the anthocorid. The anthocorid visited and ate eggs from more egg clusters than both the mirids. The two foraging strategies have been characterized as ‘find and stay’ for the mirids and ‘run and eat’ for the anthocorid. By using a stochastic exponential growth model we showed that model prey experienced different temporal dynamics when exposed to predators that differ in the probabilities of finding prey aggregations and of consuming prey within aggregations. Model prey exposed to the find and stay type of predator was less likely to become established and to increase in abundance than model prey exposed to the run and eat type. In a field study, we found a correspondence between high abundance of find and stay mirids and low densities of leaf beetles. The results suggest that, even when average predation rate is constant, the foraging strategy of the predator can have population level consequences for the prey. The consumption of prey in dense patches seems to be important in the control of gregarious prey, especially in the early phase of prey population establishment.

Dispersal of Beauveria bassiana by the activity of nettle insects

Recent studies have shown that the entomopathogenic fungus Beauveria bassiana occurs naturally on the phylloplanes of several plants, including nettles. Insects could, by their activity, be contributing to this inoculum by dispersing it from other sites. The potential of nettle aphids Microlophium carnosum and their predator Anthocoris nemorum to disperse conidia of B. bassiana from soil to nettles and from sporulating cadavers in the nettle canopy was investigated in laboratory experiments. In petri dish assays, aphids showed potential to distribute B. bassiana from soil to nettle leaves. Predators dispersed inoculum from both soil and cadavers to nettle leaves in petri dishes. In microcosms, aphids did not disperse B. bassiana from the soil or from cadavers confined in the canopy, but A. nemorum were able to transfer inoculum from soil into the nettle canopy and to distribute conidia from cryptic cadavers. In some instances, infections were initiated in aphids and predators as a consequence of dispersal.

Experimental releases of Anthocoris nemoralis F. and Anthocoris nemorum (L.) (Heteroptera: Anthocoridae) against the pear psyllid Cacopsylla pyri L. (Homoptera: Psyllidae) in pear

We investigated the potential for control of pear psyllid, Cacopsylla pyri in pear orchards by Anthocoris nemoralis and Anthocoris nemorum in semi-field and field experiments. One adult A. nemorum or A. nemoralis female reduced C. pyri eggs and young nymphs in sleeve cages by almost a third and by half respectively after two days in an experimental infestation. In a natural infestation two A. nemorum, two A. nemoralis or both together reduced C. pyri eggs and nymphs by 72–90% compared to a control in two weeks. In a small field experiment, 5–6% of introduced C. pyri remained on branches where A. nemoralis eggs had been laid, while twice as many remained on untreated branches, reflecting a significant effect of anthocorids but also considerable natural mortality. Field releases of 10 or 30 A. nemoralis nymphs per tree in three orchards in early May and again two weeks later resulted in reductions of 31–40% in C. pyri with one exception: in the orchard that had the initially highest psyllid infestation, the treatment with releases of only 10 A. nemoralis nymphs was not significantly different from the control. In general, adult anthocorids as well as nymphs brought about considerable reductions in pest numbers. Field releases show promise for developing a practical release method.