Adalia Bipunctata Research Articles

Life histories of an invasive and native ladybird under field experimental conditions in a temperate climate

AbstractAmong characteristics that are thought to determine the success of invasive species, life‐history traits feature prominently. However, in most cases, these have been determined under laboratory conditions. Here, we use a field set‐up to determine immature development time and survival of invasive Harmonia axyridis (Pallas) and native Adalia bipunctata L. (both Coleoptera: Coccinellidae). On caged Tilia × europaea L. cv. Pallida trees (Malvaceae) with ample amounts of aphid food, we introduced freshly hatched larvae of a single or of both ladybird species and followed their development until emergence of adults. Under the condition of ample prey availability, both ladybird species apparently hardly interacted and intraguild predation did not cause significant mortality. Development time of both species is in line with data from laboratory tests under controlled conditions. Immature survival can reach high levels, but is considerably higher for H. axyridis (44–100%) than for A. bipunctata (11–77%), resulting in faster increase of H. axyridis populations, which is one of the factors that may explain its invasion success.

Natural enemy composition rather than richness determines pest suppression

Natural enemy (NE) biodiversity is thought to play an important role in agricultural pest suppression. However, the relative importance of the number of NE species (species richness), versus the particular combinations of species (species composition), in determining aphid suppression and ultimately crop yields, remains poorly understood. We tested the effects of NE richness and composition on pea aphids Acyrthosiphon pisum (Harris) and broad bean plants Vicia faba (Linn.). We used the larvae of two predator species, the ladybird Adalia bipunctata (Linn.) and the green lacewing Chrysopa carnea (Stephens), and the parasitic wasp Aphidius ervi (Haliday) as enemies. NEs generally reduced aphid density but did not increase final plant biomass, despite a significant negative correlation between aphid density and plant biomass. Among NE treatments, species richness had an inconsistent effect on aphid density. The composition of NEs within richness levels also affected final aphid density: the ladybird was a key species among the treatments in controlling aphid density and was especially effective in combination with the parasitoid. This ladybird/parasitoid combination also appeared to drive the higher level of suppression observed at the two, relative to three, species richness levels. Although these three species of aphid NEs are commonly used in aphid control, this is the first study, to our knowledge, that simultaneously examined these three species and highlighted the composition effect between the A. bipunctata and A. ervi. In conclusion, increasing NE species richness had an inconsistent effect on aphid density. Meanwhile, the presence of a key species (the ladybird) and its combination with a parasitoid was an important determinant of aphid biological control.

The influence of microsporidian pathogens from commercially available lady beetles on larval development of the green lacewing, Chrysoperla carnea, in the absence of infection.

In North America, more than 70 species of natural enemies are available for pest control, including the aphid predators, Adalia bipunctata L. (two-spotted lady beetle) and Hippodamia convergens Guérin-Méneville (convergent lady beetle), and the generalist predator Chrysoperla carnea Stephens (green lacewing). The two lady beetle species are known to host microsporidian pathogens: Nosema adaliae was originally described from Adalia bipunctata and Tubulinosema hippodamiae from H. convergens. Microsporidia are spore-forming pathogens that typically produce chronic, debilitating disease. Because the spores of both pathogens are transovarially transmitted through beetle eggs, the predation behavior of lacewing larvae provides an opportunity for the transmission of these pathogens when infected lady beetles and lacewings share the same local environment. In this study, uninfected and microsporidia-infected eggs from A. bipunctata and H. convergens were offered to C. carnea larvae. The development of larvae that consumed N. adaliae-infected eggs was not affected, but larval development was prolonged by almost 3 days for those that consumed two or more T. hippodamiae-infected eggs. Prolonged larval development is considered to be costly because larvae remain vulnerable to cannibalization by sibling larvae or other predators. Longevity did not differ significantly between sexes of C. carnea, and the sex ratio of newly eclosed adults did not differ from the previously reported sex ratio of 1♂: 1♀. Upon examination by light microscopy at the end of the trial, two C. carnea larvae were infected with N. adaliae and none were infected with T. hippodamiae, suggesting that T. hippodamiae influenced lacewing larval development without establishing an infection.

Invasive Egg Predators and Food Availability Interactively Affect Maternal Investment in Egg Chemical Defense

Invasive species commonly predate the offspring of native species and eggs are the life stage most vulnerable to this predation. In many species with no maternal care, females can alter the phenotype of eggs to protect them, for instance through chemical defence. In ladybirds egg alkaloids deter predators, including invasive predatory species of ladybirds, but conversely may attract cannibals who benefit from the consumption of eggs with higher alkaloid levels. Invasive predators tend to be more abundant where resources are also abundant, but in high resource environments the maternal fitness benefits of sibling cannibalism are low. Consequently this presents a conflict for female ladybirds between the different factors that influence egg alkaloid level, as protecting her eggs from predators might come with the cost of inadvertently encouraging within-clutch cannibalism under circumstances where it is not beneficial. We investigated how the ladybird Adalia bipunctata addresses this trade-off experimentally, by measuring the quantity of alkaloids in eggs laid by ladybirds in environments that differed in levels of resource availability and perceived predation risk from an invasive predator Harmonia axyridis. Females did lay eggs with higher egg alkaloid levels under poor resource conditions, but only when predator cues were absent. The resulting negative correlation between egg number and egg alkaloid level under poor resource conditions indicates a trade-off between these two attributes of maternal investment, mediated by female response to offspring predation risk. This implies that selection pressures on mothers to adaptively adjust the risk of siblicide may outweigh the need to protect offspring from interspecific predation. Our results demonstrate that maternal effects are an important aspect of species’ responses to invasive predators, and highlight the value of studying maternal effects in the context of the multifaceted environments in which they occur.

Lecanicillium muscarium and Adalia bipunctata combination for the control of black bean aphid, Aphis fabae

The predator Adalia bipunctata (Coleoptera: Coccinellidae) and the entomopathogenic fungus Lecanicillium muscarium, have been considered as potential biological control against aphids. While it can be difficult to achieve a high control level of Aphis fabae Scopoli (Hemiptera: Aphididae) using only a single beneficial agent, the research presented here aimed to determine the interaction between L. muscarium and A. bipunctata potential for control against A. fabae. Lecanicillium muscarium was found to cause about 30% mortality in A. bipunctata and with a reduction in feeding by about 15%. However, co-application of A. bipunctata and L. muscarium can cause an addititive effect in reducing aphid populations, resulting in about 90% reduction in aphid populations compared with control treatment. Thus, these two biocontrol agents have the potential to be complementary. This research study demonstrates that it is possible to combine A. bipunctata with L. muscarium to provide a sustainable method for management of A. fabae on broad bean cropping system and that field studies are required.

Distribution and Some Biological Features of Invasive Species Harmonia axyridis in the Crimea

We present data on the distribution of an invasive species Asian ladybird Harmonia axyridis in the Crimea, the presence in Crimean populations of different morphological types of H. axyridis, and the population ratio of the two most numerous species of Coccinellidae, namely, Harmonia axyridis and Adalia bipunctata, in connection with their possible competition.

THE IMPORTANCE OF PREDATORS IN CEREAL CROP AGROBIOCENOSIS IN LESKOVAC

The monocultural way of grain crop production may cause the massive emergence and development of both harmful and useful organisms in agrobiocenosis. Predators as natural enemies give a significant contribution to the reduction of pest population. The aim of the research was to monitor the biodiversity of predators and establish the differences in their faunistic composition, with regard to the agrobiocenosis of both spring and winter crops. The following standard entomological methods were used throughout the research: visual inspection, examination of above-ground parts of a plant, the sweep net method and laboratory processing of gathered material. The research was carried out from 2011 to 2013 on the experimental plot of the Agricultural High School in Leskovac. The research shows that the diversity maintenance and natural bioregulatory mechanisms are the basic rule in preservation of the grain agrobiocenosis against harmful insects. The predatory activities towards aphids were registered among the following five species of ladybirds belonging to the family of Coccinellidae: Coccinella septempunctata L., Adalia bipunctata L., Hippodamia variegata Goeze, Propylea quatourdecimpunctata L. and Calvia quatourdecimpunctata L. and 2 predators of family Chrysopidae: Chrysopa perla L. and Chrysopa carnea Steph. The research results showed similarity among ogranisms present in respective agrobiocenoses of spring and winter crops that were compared.

Do Bioflavonoids in Juniperus virginiana Heartwood Stimulate Oviposition in the Ladybird Coleomegilla maculata?

Maximizing the reproductive potential of ladybird beetles fed factitious foods or artificial diets, in lieu of natural prey, is a major challenge to cost-effective mass rearing for augmentative biological control. In this study, we tested the hypothesis that compounds in redcedar, Juniperus virginiana, stimulate oviposition in the ladybird Coleomegilla maculata. We also tested the prediction that several bioflavonoids, identified in heartwood fractions, elicited this behavioral response. Phenolic compounds were extracted from J. virginiana heartwood sawdust, separated into several fractions, then presented to adult beetles, in a powdered, pure form, in the laboratory. Females preferentially oviposited within 1 to 2 cm of fractions B, C, D, and E, but not A or the unfractionated extract, at the base of test cages. Chemical analysis identified bioflavonoids in heartwood fractions and subsequent bioassays using several identified in fractions C, D, and E confirmed that quercetin, taxifolin, and naringenin (to a lesser extent) stimulated oviposition. All tested fractions and bioflavonoids readily adhered to the chorion of freshly laid eggs but did not reduce egg hatch. This study demonstrates that several bioflavonoids stimulate oviposition by C. maculata and could be useful for mass rearing programs.

Thiamethoxam seed treatments reduce foliar predator and pollinator populations in sunflowers (Helianthus annuus), and extra-floral nectaries as a route of exposure for seed treatments to affect the predator, Coleomegilla maculata (Coleoptera: Coccinellidae)

Neonicotinoid seed-treatments are used frequently in sunflower production to prevent early-season herbivory, and have been implicated in declines in non-target species. Over three site-years, both insecticide treated (Cruiser®, rate: 0.25 mg a.i. (thiamethoxam)/seed) and untreated sunflower (Helianthus annuus [Family: Asteraceae]) fields were planted in Eastern and Central South Dakota. Foliar and subterranean predatory arthropod communities and pollinator populations were compared among the two treatments. A greenhouse study was performed to collect and quantify toxins in extra-floral nectar from treated and untreated sunflowers. A laboratory assay was performed to examine the effect of an artificial nectar diet laced with thiamethoxam or clothianidin on survival, fecundity and mobility of Coleomegilla maculata (De Geer [Coleoptera: Coccinellidae]). Seed-treated fields had significantly fewer above-ground natural enemies and pollinators than untreated fields, while subterranean predators were unaffected. Beetle flip-over times increased as concentration of thiamethoxam in diet increased, but clothianidin showed no effect. Neither toxin affected number of eggs oviposited by beetles, or size of developing oocytes. However, there was a negative correlation between increasing thiamethoxam concentration and number of developing eggs. Extra-floral nectar (EFN) collected from treated greenhouse-grown plants contained thiamethoxam (range: 1.23 ± 0.09 ppb to 4.83 ± 0.63 ppb), but no clothianidin. Toxin-laden EFN was identified as a potential route of exposure between beneficial arthropods and seed-applied neonicotinoids. Risks of neonicotinoid seed treatment use are discussed in the light of additional exposure pathways being confirmed.

Behavioral and Immunological Features Promoting the Invasive Performance of the Harlequin Ladybird Harmonia axyridis

The harlequin ladybird Harmonia axyridis is now established as a model to test hypotheses explaining why some species become successfully invasive, while others, even closely related ones, do not. In this review, we evaluate behavioral and immunological features that may play a role in the invasive performance of this model species. We discuss the behavioral traits and associated semiochemicals that promote the invasive success of H. axyridis. In particular, we consider (1) the aggregative behavior and the particular role of long-chain hydrocarbons; (2) the importance of sex pheromones and non-volatile chemicals in mate location and selection; (3) the use of allelochemicals for prey location; and (4) the nature of chemicals that protect against natural enemies. We also highlight the superior immune system of H. axyridis, which encompasses a broader spectrum of antimicrobial peptides (and higher inducible expression levels) compared with native ladybird beetles such as Adalia bipunctata and Coccinella septempunctata. The chemical defense compound harmonine and the antimicrobial peptides are thought to confer resistance against the abundant microsporidia carried by H. axyridis. These parasites can infect and kill native ladybird species feeding on H. axyridis eggs or larvae, supporting the hypothesis that intraguild predation plays a role in the ability of H. axyridis to outcompete native ladybird species in newly-colonized areas.

Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines

In the last two decades a huge amount of research has focused on the invasive harlequin ladybird, Harmonia axyridis, particularly on potential or actual deleterious effects that have arisen after it has colonised new regions. A focus of this work has been real or anticipated declines in native ladybird abundance since the introduction of H. axyridis, for which it is deemed responsible. Scientists have generally painted a very bleak picture of the effects of H. axyridis on native species: in this paper I argue that the picture painted is often too bleak. I use the case of the 2-spot ladybird, Adalia bipunctata, the species most often invoked as threatened by H. axyridis, to illustrate my point. While there is little question that H. axyridis has led to a decline in A. bipunctata populations in Europe, it seems likely that prior to the invasive ladybird's arrival A. bipunctata occurred in artificially high numbers in the urban environments in which it was typically studied. Pollution in towns and cities led to enhanced numbers of prey aphids on plants there which initially favoured A. bipunctata, and later H. axyridis. Thus one species, A. bipunctata, that has benefitted from an association with humans has been replaced by another, H. axyridis, just as brown rats replaced black rats in Europe and North America. Viewed with a longer perspective, A. bipunctata has more likely declined back to pre-industrial levels: the artificially high level from which it has declined recently was not a 'natural' one, and thus its decline from this level does not imply that it is now threatened or endangered. More broadly, we need a wider perspective, encompassing other ladybirds, longer timeframes and better comparisons with other (non-ladybird) invasive species to more clearly assess whether H. axyridis really poses as much of a threat as is often proposed.

Lethal and Sub-lethal Effects of Four Insecticides on the Aphidophagous Coccinellid Adalia bipunctata (Coleoptera: Coccinellidae).

Conventional insecticide assays, which measure the effects of insecticide exposure on short-term mortality, overlook important traits, including persistence of toxicity or sub-lethal effects. Therefore, such approaches are especially inadequate for prediction of the overall impact of insecticides on beneficial arthropods. In this study, the side effects of four modern insecticides (chlorantraniliprole, emamectin benzoate, spinosad, and spirotetramat) on Adalia bipunctata (L.) (Coleoptera: Coccinellidae) were evaluated under laboratory conditions by exposition on treated potted plants. In addition to investigation of acute toxicity and persistence of harmful activity in both larvae and adults of A. bipunctata, demographic parameters were evaluated, to provide a comprehensive picture of the nontarget effects of these products. Field doses of the four insecticides caused detrimental effects to A. bipunctata; but in different ways. Overall, spinosad showed the best toxicological profile among the products tested. Emamectin benzoate could be considered a low-risk insecticide, but had high persistence. Chlorantraniliprole exhibited lethal effects on early instar larvae and adults, along with a long-lasting activity, instead spirotetramat showed a low impact on larval and adult mortality and can be considered a short-lived insecticide. However, demographic analysis demonstrated that chlorantraniliprole and spirotetramat caused sub-lethal effects. Our findings highlight that sole assessment of mortality can lead to underestimation of the full impact of pesticides on nontarget insects. Demographic analysis was demonstrated to be a sensitive method for detection of the sub-lethal effects of insecticides on A. bipunctata, and this approach should be considered for evaluation of insecticide selectivity.

Native ladybird decline caused by the invasive harlequin ladybird Harmonia axyridis: evidence from a long‐term field study

Abstract Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is regarded as an invasive non‐native species in Europe, where it has been spreading rapidly since the early years of the 21st century. This study examines changes in ladybird communities at four sites (two lime tree sites, one pine tree site and one nettle site) in East Anglia, England, over an 11‐year period (2006–2016) following invasion by H. axyridis. Overall, H. axyridis represented 41.5% of all ladybirds sampled [varying from a low of 0.2% (1 of 520 ladybirds at three sites) in 2006 to a high of 70.7% (724 of 1024 at four sites) in 2015] and was over three times more abundant than the second commonest species, Coccinella septempunctata L. The proportion of native ladybirds declined from 99.8% (520 of 521 ladybirds at three sites) in 2006 to 30.7% (383 of 1248 at four sites) in 2016, but H. axyridis dominated only at the lime tree sites and not at the pine or nettle sites. There was a significant negative relationship between H. axyridis and Adalia bipunctata (L.) (Coleoptera: Coccinellidae) adults at the lime tree sites, but not between H. axyridis and adults of any of the other main ladybird species sampled. Adalia bipunctata adults and Adalia spp. larvae were the only native ladybirds that significantly declined. Our study shows a clear change in the ladybird community on lime trees over an 11‐year period in which H. axyridis invaded England. Intraguild predation is hypothesised to be an important driver of the changes observed.

A selective insecticidal protein from Pseudomonas mosselii for corn rootworm control.

SummaryThe coleopteran insect western corn rootworm (WCR, Diabrotica virgifera virgifera) is an economically important pest in North America and Europe. Transgenic corn plants producing Bacillus thuringiensis (Bt) insecticidal proteins have been useful against this devastating pest, but evolution of resistance has reduced their efficacy. Here, we report the discovery of a novel insecticidal protein, PIP‐47Aa, from an isolate of Pseudomonas mosselii. PIP‐47Aa sequence shows no shared motifs, domains or signatures with other known proteins. Recombinant PIP‐47Aa kills WCR, two other corn rootworm pests (Diabrotica barberi and Diabrotica undecimpunctata howardi) and two other beetle species (Diabrotica speciosa and Phyllotreta cruciferae), but it was not toxic to the spotted lady beetle (Coleomegilla maculata) or seven species of Lepidoptera and Hemiptera. Transgenic corn plants expressing PIP‐47Aa show significant protection from root damage by WCR. PIP‐47Aa kills a WCR strain resistant to mCry3A and does not share rootworm midgut binding sites with mCry3A or AfIP‐1A/1B from Alcaligenes that acts like Cry34Ab1/Cry35Ab1. Our results indicate that PIP‐47Aa is a novel insecticidal protein for controlling the corn rootworm pests.

Lethality of the Entomogenous FungusBeauveria bassianaStrain NI8 onLygus lineolaris(Hemiptera: Miridae) and its Possible Impact on Beneficial Arthropods

Abstract Bioassays were conducted to examine the pathogenicity of the fungus Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales), strain NI8, against Lygus lineolaris (Palisot de Beauvois) and its impact on beneficial arthropods including Apis mellifera L., Crysoperla rufrilabris Burmeister, Orius insidiosus Say, Hippodamia convergens Guerin-Meneville, Harmonia axyridis (Pallas), Coleomegilla maculata De Geer, and field-collected Aranea spiders Salticidae and Thomisidae. Insects were treated with four concentrations of NI8 (3.9 × 104, 2.3 × 105, 4.2 × 106, and 1.5 × 107 spores/ml) directly via topical spray. Median lethal concentration (LC50), sporulation response, and resistance ratio were estimated for all species except for the two groups of spiders. No significant differences in mortality (10 d after application) were observed among L. lineolaris, A. mellifera, and C. rufilabris, and all three species were highly affected when exposed to the highest concentrations of B. bassiana with 99.0...

Differences in Flight Activity of Coleomegilla maculata and Hippodamia convergens (Coleoptera: Coccinellidae) Following Emergence, Mating, and Reproduction.

The flight activity of Coleomegilla maculata DeGeer and Hippodamia convergens Guerin-Meneville (Coleoptera: Coccinellidae) was examined by observing tethered beetles in the laboratory. C. maculata were fed eggs of Ephestia kuehniella Zeller, as were larval H. convergens, whereas adult H. convergens were fed Melanaphis sacchari (Zehntner) to induce egg maturation; adults of both species received water and diluted honey. A spot of magnetic paint was applied to one elytrum of each beetle, which then adhered to a small neodymium magnet attached to a thread. Beetles were permitted 1 h flight opportunities daily for 3-d periods, first as virgins on their fifth day of adult life, secondly after mating, thirdly after females began oviposition, and fourthly after prey were withheld and egg maturation and oviposition ceased. Both species exhibited low flight activity as virgins, and whereas C. maculata females increased their activity after mating, H. convergens females did not. Flight activity in C. maculata did not change with onset of oviposition, whereas it increased in H. convergens males, but not females. In contrast, H. convergens females increased their flight activity after cessation of oviposition, whereas C. maculata females did not. Female flight activity when either virgin or mated correlated weakly with fecundity in C. maculata, but not in H. convergens. Species differences are discussed in the context of nutritional ecology; H. convergens usually enters diapause immediately following emergence, and is more dependent on aphids for reproduction, whereas C. maculata develops and reproduces on a wider range of foods and is not so constrained.

No nutritional benefits of egg cannibalism for Coleomegilla maculata (Coleoptera: Coccinellidae) on a high-quality diet.

Egg cannibalism serves various functions in the Coccinellidae. Here we examined the fitness consequences of egg cannibalism by neonates, fourth instar larvae, and prereproductive adults of Coleomegilla maculata DeGeer, with beetles fed a diet of Ephestia kuehniella Zeller eggs. Cannibalism of two eggs by neonates had no effect on development, and cannibalism of five eggs by fourth instars did not benefit any aspect of reproduction, but delayed pupation slightly. Cannibalism of eggs by pre-reproductive adults had no effect on reproductive success in any combination of reciprocal crosses of cannibals and non-cannibals. Females did not recognize, nor avoid consuming, their own clutches, and cannibalism propensity did not change following mating and onset of oviposition in either sex. These results contrast with those for more strictly aphidophagous species in which larvae gain developmental benefits, and females may recognize and avoid filial egg clusters while using cannibalism to interfere with conspecific females, whereas males reduce egg cannibalism after mating because they cannot recognize filial clusters. Egg cannibalism may confer developmental benefits to C. maculata when diet is suboptimal, as previously shown, but no such benefits were evident on the high-quality E. kuehniella egg diet. Female C. maculata do not require aphids to reproduce and distribute their eggs broadly in the environment, given that larvae can develop on pollen and non-aphid prey. Thus, C. maculata is not subject to the intraspecific competition that selects for cannibalism in more aphidophagous species, and also lacks many secondary adaptations associated with the behaviour.

Effect of provision of apiaceous flowers associated to foods on the biology of Coleomegilla maculata

Coleomegilla maculata DeGeer is an omnivorous lady beetle that feeds on natural or alternative prey and artificial foods, which allows its laboratory rearing for use on augmentative biocontrol. In addition, C. maculata may supplement its diet with pollen and nectar, which helps in its conservation in agroecosystems. This study aimed to evaluate if Apiaceous flowers (Anethum graveolens L. and Coriadrum sativum L.), with and without alternative prey [eggs of Ephestia kuehniella (Zeller) or larvae of Drosophila melanogaster Meigen] or an artificial food (aqueous solution of honey), may guarantee the survival and complete development of the immature and adult stages of C. maculata in the laboratory. The immature stages developed only when Apiaceous flowers were offered with E. kuehniella eggs. The food with only one of the alternative prey (moth eggs or fly larvae) or moth eggs + honey solution resulted in fertile adults; however, the number of eggs/cluster was greater for the foods with E. kuehniella eggs + honey solution, A. graveolens flowers, or only D. melanogaster. Foods comprising only the two Apiaceous species, only the honey solution, or only water resulted in larval development up to a specific instar. Adults of C. maculata also survived on these foods, but there was no oviposition. The foods of the two Apiaceous species produced heavier adults only when associated with E. kuehniella eggs. The results indicate that the zoophytophagous habit of C. maculata should be considered in conservation biocontrol programs aimed at using this lady beetle to control crop pests.

Four species of lady beetles (Coleoptera: Coccinellidae) exhibit limited predation on Nezara viridula (Hemiptera: Pentatomidae) eggs and nymphs

The Coccinellidae (Coleoptera) co-occur in many habitats with many arthropods that are of suitable size as prey. The Pentatomidae (Hemiptera) are one such group of insects with eggs and early instars that could be susceptible to predation by Coccinellidae. The objective of this laboratory study was to examine if predation by adult and larval Coccinellidae occurred on the eggs and 1st instars of Nezara viridula (L.) (Hemiptera: Pentatomidae). We tested whether live eggs, live nymphs, or dead nymphs (recently frozen) would be fed on by Coleomegilla maculata, Harmonia axyridis, Hippodamia convergens and Olla v-nigrum (Coleoptera: Coccinellidae). Our results show that starved 4th instars and adults of all tested Coccinellidae cannot feed on N. viridula eggs. More feeding by larval lady beetles occurred on recently frozen, dead 1st instars than on live 1st instars. The exception to this was larval C. maculata which fed similarly on live and dead nymphs. Adult lady beetles did not feed on live 1st instar N. viridula. Observations indicated that in some instances, a live N. viridula nymph was capable of repelling a predator. From this study, it is unlikely that the Coccinellidae contribute to substantial predation of N. viridula eggs and nymphs.

Monitoring giant willow aphid (<i>Tuberolachnus salignus</i>) on apple trees in close proximity to infested willows


 
 
 The giant willow aphid, was first found in New Zealand in 2013 and is now established throughout the country. An orchardist in the Tasman district reported infestation of his commercial block of young ‘Envy’ apple trees after harvest in May 2016, adjacent to two large willow trees heavily infested with giant willow aphid. Regular observations commenced soon after to determine seasonal activity, apple tree infestation, timing and impact and any alternative host plants or possible natural enemies. Key observations since are that the giant willow aphids appear in late September on willow shoots near the base of the tree reaching low numbers before disappearing again in late November. At this time, a ladybird species (Adalia bipunctata), where observed in the willows and on other plants nearby. In late December the aphids reappeared on the willows and numbers built to a peak in late February and remained on the willows until leaf fall. The aphids were not seen on the apple trees in any signi cant numbers until February when infestation and feeding continued until late autumn. After two seasons of infestation, the apple trees closest to the infested willows are now visibly ‘sick’ with yellowing leaves, stunted growth, reduced fruit production and branches blackened with sooty mould.