The establishment ofRhyzobius forestieri [Col.: Coccinellidae] in greece and its efficiency as an auxiliary control agent against a heavy infestation ofSaissetia oleae [Hom.: Coccidae]

Introduction releases of the exotic coccinellid predatorRhyzobius forestieri Mulsant were made in 22 localities throughout Greece. The releases were made on olive, citrus, fig and almond trees infested with differentCoccidae scales. In 9 of these localities,R. forestieri was recovered 2–5 months later. The most important factor for the successful establishment ofR. forestieri seems to be an abundance of scales on the trees. To study the ability ofR. forestieri to enhance overall predation, 3 releases were made in an olive grove heavily infested withSaissetia oleae Olivier on Chios island during 1982 and 1983. The experiment began in June 1982. By April 1983, theS. oleae infestation was clearly in the process of being controlled by the coccinellid. A native coccinellid,Exochomus quadripustulatus L., contributed little during this period because of its obligatory estival diapause. The other main coccinellid,Chilocorus bipustulatus L., made an appreciable contribution toward achieving control during the summers of 1982 and 1983, but it was affected from July onward by increasing parasitism of its larvae. Both species are quiescent during the winter months. The introduced speciesR. forestieri was readily established in the olive grove and multiplied quickly. One month after the initial release,R. forestieri larvae made up most of the coccinellid larval population in the field. Thereafter until April 1983,R. forestieri larvae and adults comprised the dominant coccinellid population in the olive grove. During the winter months,R. forestieri remains active as long as temperature exceeds 8 °C. The important increase inR. forestieri's population size between July 1982 and April 1983 coincided with the increased rate of predation onS. oleae. This suggests thatS. forestieri played a key role in bringing theS. oleae infestation under control during this period. After April 1983, however, theR. forestieri population diminished rapidly andC. bipustulatus became the dominant coccinellid in the olive grove. It is believed that scarcity of prey was the cause of this reversal: by April 1983, the density ofS. oleae in the olive grove had already been reduced by about 100 times.     

Distribution of the spider community in the olive grove agroecosystem (Portugal): potential bioindicators

1. Spiders are successful natural enemies in different crops. Research on the role of spiders as natural enemies within agroecosystems needs to address the distribution of their communities across different spatial scales, as well as the dominant species.
2. We studied the spatial distribution of the community of spiders of the olive agroecosystem in Northeastern Portugal and investigated potential species that could be used as bioindicators of agricultural management in the olive grove.
3. We found nine functional groups (ambushers, foliage runner hunters, ground hunters, orb‐web builders, sheet web builders, sensing web‐builders, space web builders, stalkers and wandering sheet/tangle weavers) encompassing a community that changed significantly across the horizontal and vertical gradient.
4. We propose Thanatus vulgaris Simon, 1870 as potential bioindicator for the ground of the olive grove central area and Ozyptila pauxilla (Simon, 1870) for the ground of the olive grove peripheral area.
5. Adjacent shrubland areas could play an important role in biological control of pests, allowing the exchange of species and individuals with the olive crop. The role of agrobiont species as indicators of agricultural managements deserves further investigation towards the enhancement of the effectiveness of spiders within low‐impact crop management in arable landscapes.

     

Selective toxicity of some pesticides to Pullus mediterraneus Fabr. (Coleoptera: Coccinellidae), a predator of Saissetia oleae Bern. (Homoptera: Coccoideae)

• 1 To contribute to the development of IPM strategies in olive groves, the selectivity of several insecticides to Pullus mediterraneus Fabr. (Coleoptera: coccinellidae) was investigated in the laboratory. The study assessed the toxicity of seven chemical pesticides and one bacteriological insecticide to adult P. mediterraneus.
• 2 The LC₅₀ was estimated by applying the pesticides on the dorsal side of adults. Lambda‐cyhalothrin, methomyl and cypermethrin resulted in the highest toxicity followed, in decreasing order of toxicity, by malathion, fenthion and dimethoate. Parathion had the least effect on the coccinellid.
• 3 Consumption of Bacillus thuringiensis bacteria (applied as a commercial formulation), over a period of 10 consecutive days, resulted in low mortality of adult P. mediterraneus.
• 4 The results of these laboratory experiments indicate that the most widely used chemical pesticides were toxic to P. mediterraneus. Their use in olive groves must take account of the activity period of this predator. In contrast, B. thuringiensis seemed to be a suitable candidate to be included in pest management systems.

     

Wax covers in larvae of two Scymnus species: do they enhance coccinellid larval survival?

We tested the protective function of larval wax covers in the two ladybird beetle species, Scymnus nigrinus and S. interruptus, against cannibalism, predation and ant aggression, and its importance for the distribution of both species in the field. Cannibalism was generally very low and not influenced by the presence or absence of the wax cover, or by larval size. Fourth-instar larvae of three ladybird species, Adalia bipuncata, Exochomus quadripustulatus and Harmonia quadripunctata, consumed Scymnus larvae-which are much smaller-regularly, independent of the presence or absence of waxes. By contrast, first-instar larvae of the three species had generally little success when attacking Scymnus spp. larvae. Wax-covered S. interruptus larvae survived significantly more attacks by the predacious carabid beetle Platynus dorsalis than larvae without wax cover. Wax-covered S. interruptus larvae and S. nigrinus larvae survived attacks by workers of the ant species, Lasius niger and Formica polyctena, respectively, significantly more often than larvae without wax covers. We show that, in the field, Scymnus larvae have higher densites in ant-attended resources than in unattended ones and conclude that both Scymnus species benefit from the ability to feed in ant-attended aphid colonies by a reduced predation risk.     

Effects of an invading coccinellid on native coccinellids in an agricultural landscape

Seven native coccinellid species inhabited alfalfa, corn, and small grain fields in eastern South Dakota prior to invasion and establishment of Coccinella septempunctata L. Six species occurred in all crops, however, Adalia bipunctata (L.) occurred only in corn. The structure of native coccinellid communities differed significantly for years prior to compared with years after establishment of C. septempunctata in fields of the three agricultural crops. Differences in community structure were accounted for mainly by reduced abundance of two species, C. transversoguttata richardsoni Brown and Adalia bipunctata (L.). Annual abundance of C. transversoguttata richardsoni averaged 20–32 times lower during post-invasion years than in years prior to invasion, depending on crop; while annual abundance of A. bipunctata averaged 20 times lower in corn after invasion. Addition of C. septempunctata to the community did not result in a significant increase in total abundance of coccinellids in the crops. Coccinellid abundance in agricultural crops may be limited by the total abundance of prey or by the availability of other requisites in the landscape as a whole. Therefore, introduction of a new species, while resulting in reductions in native species populations, may not increase total coccinellid abundance, and may therefore have no net effect on biological control of aphid pests.     

Evaluating potential sugar food sources from the olive grove agroecosystems for Prays oleae parasitoid Chelonus elaeaphilus

Chelonus elaeaphilus Silvestri (Hymenoptera: Braconidae) is a host-specific parasitoid of the olive moth, Prays oleae (Bernard), that can cause parasitism rates of up to 80% in Mediterranean olive groves. A laboratory study was carried out to assess the potential of sugars provided by wild plant species in olive grove agroecosystem to enhance the fitness of C. elaeaphilus. Insects were reared in a climate-controlled chamber at 25?±?2°C, 60?±?5% relative humidity (RH) with a photoperiod of 16:8 (L:D) h. Five naturally occurring wild plant nectar sugars (sucrose, fructose, glucose, maltose and mannose) were tested for their effect on insect longevity. The nectar sugar content of sucrose, fructose and glucose in 12 selected olive grove agroecosystem plant species was analysed and categorised on the basis of sugar ratios. Female insect longevity was increased when they were fed on both sucrose and glucose compared to either maltose or fructose, suggesting that sucrose-dominant nectars would bene?t this parasitoid. Sucrose was predominant in the nectar of five of the studied plant species (Silene gallica, Borago officinalis, Echium plantagineum, Lavandula stoechas and Lonicera hispânica). The results are discussed in terms of potential enhancement of the biological control of P. oleae.     

Detecting seasonal variation in composition of adult Coccinellidae communities

1. Following its recent global spread, Harmonia axyridis (Coleoptera: Coccinellidae), an aphid predator of East Palearctic origin, dominated local coccinellid communities. While long‐term trends in this change are well documented, little is known about seasonal changes. 2. Seasonal changes in communities of adult Coccinellidae were investigated in central Europe (Prague), from April to November in 2010–2014. The beetles were collected at 2‐weekly intervals by net‐sweeping particular stands of trees (Tilia spp., Acer spp. and Betula sp.). The numbers of beetles caught were recalculated per unit effort, and average species abundance and community richness, dominance and diversity were calculated for each 2‐week period. 3. Frequencies of 21 established species varied throughout the vegetative season and general trends in this variation were similar in each of the 5 years of this study. In May–June the abundant species was Adalia decempunctata, which was later replaced by Harmonia axyridis as the most abundant species in late summer. Coccinella septempunctata colonized trees occasionally in summer. This sequence of species substitution occurred every year and was reset during winter. Species richness decreased and dominance increased during the course of each vegetative season. The diversity of the coccinellid community (Shannon index H′) significantly decreased during the course of the vegetative season. This was caused by a gradual increase in the dominance of H. axyridis, the abundance of which explained 88% of variation in H′. 4. The existence of a significant seasonal difference indicates that it is important to take this into consideration when comparing coccinellid communities.     

Potential spatial interaction of the invasive species Harmonia axyridis (Pallas) with native and endemic coccinellids

Biological invasions represent a serious menace to local species assemblages, mainly due to interspecific relationships such as competition and predation. One important invasive species worldwide is Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), which has invaded many regions of the world, threatening the native and endemic coccinellid assemblages due to negative interspecific interactions. These interactions have been widely studied at a local scale, but have been less studied at regional scales. Our aim was to estimate and analyse the potential spatial interaction associated with the co‐occurrence of H. axyridis with native and endemic species in Chile, considering bioclimatic and land cover variables. First, we created species distribution models (SDM) for H. axyridis, native and endemic coccinellids and six representative coccinellid species using maximum entropy technique. Then, we overlapped each SDM with land cover types to estimate the bioclimatic suitability within each land cover type. Finally, we identified the co‐occurrences of organisms according to the SDM and the land cover types, estimating in what land covers H. axyridis and the other coccinellids are more likely to co‐occur. Our results show that the suitable area for H. axyridis occurs from 30° to 42°S in Chile, while for native and endemic species this area is greater. The six selected species are mainly concentrated in central Chile, but differ in their potential suitable areas; Adalia angulifera Mulsant and Scymnus bicolor (Germain) have the largest range, and Mimoscymnus macula (Germain) has the most restricted one. The highest level of potential spatial interactions with H. axyridis occurs in central Chile, specifically in croplands and scrublands, and the lowest in primary native forest for all the species. Our results provide a spatially explicit baseline for coccinellid conservation and management of this invasive species.     

Exploring the effect of soil management intensity on taxonomic and functional diversity of ants in Mediterranean olive groves

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Toxicity of plant essential oil vapours to aphid pests and their coccinellid predators

The comparative toxicity of five essential oil vapours was tested against four aphid species, the black bean aphid Aphis fabae, the pea aphid Acyrthosiphon pisum, the chrysanthemum aphid Macrosiphoniella sanborni, the green peach aphid Myzus persicae and on two of the most common coccinellid predators, the seven-spotted ladybird Coccinella septempunctata and the two-spotted ladybird Adalia bipunctata. All essential oils were highly toxic to the aphid species tested with LC₅₀ and LC₉₉ values ranging between 0.17 and 1.92 and 0.44 and 4.83 µL/L air, respectively, depending on the aphid species and on the essential oil. Coccinellid predators were also highly susceptible to the essential oil vapours and the selective toxicity ratio varied depending on aphid species, coccinellid predator and essential oil. The possibilities for the utililization of essential oils as aphicides, especially in IPM programmes in glasshouses are discussed with regard to the present findings.     

Defensive behaviour of the wheat aphid,Schizaphis graminum (Rondani) (Hemiptera: Aphididae), against Coccinellidae

An account is given of the behaviour of the wheat aphid, Schizaphis graminum, in response to attacks by two coccinellid predators Scymnus morelleti and Exochomus concavus. Various responses are described and their influence on predator efficiency is investigated.     

Diversity and abundance of coccinellids (Coleoptera: Coccinellidae) on trees in parks and tree rows of Belgrade

Harmonia axyridis is an invasive coccinellid species that was first recorded in Serbia in 2008. In order to establish whether after its arrival it became the dominant coccinellid species, we investigated the diversity and abundance of coccinelids on trees in parks and tree rows of Belgrade during 2015 and 2016. Thirteen coccinellid species were recorded in these investigations. Frequently occurring among them were Adalia bipunctata, A. decempunctata, Coccinella septempunctata, Exochomus quadripustulatus, Harmonia axyridis, H. quadripunctata, Oenopia conglobata, and Popylea quatuordecimpunctata. All of them had different dynamics of appearance during the vegetation. As a result of this, the values of their dominance in the coccinellid community constantly changed. However, only in the cases of H. axyridis, O. conglobata, and C. septempunctata were those values high enough for us to be able to say that they were dominant in terms of abundance during a certain period. Although the amounts of summer precipitation in Serbia were very different during 2015 and 2016, the trends of changes in the diversity of coccinellids throughout the growing season in these two years were similar.     

Intraguild predation by Harmonia axyridis (Coleoptera: Coccinellidae) on native insects in Europe: molecular detection from field samples

Intraguild predation (IGP) is a potential mechanism of negative effects on native species populations by invasive non‐native species such as Harmonia axyridis. Molecular techniques (polymerase chain reaction) were used to probe for the presence of various insect (coccinellid, syrphid and chrysopid) prey DNA in the guts of 177 H. axyridis larvae field‐collected in England, France, Germany, Slovakia and the Czech Republic in 2010. Three of the four target prey species were detected in the guts of H. axyridis at the following rates: Adalia decempunctata 9.6%, Adalia bipunctata 2.8% and Episyrphus balteatus 2.8%. IGP on Chrysoperla carnea was not detected. IGP detection of at least one target species was made in England, France, Slovakia and the Czech Republic, but not in Germany. These results strengthen the evidence that H. axyridis is a very generalist predator. Results are discussed in the context of their ecological significance.     

Searching by Adalia bipunctata (L.) (Coleoptera: Coccinellidae) and escape behaviour of its aphid and cicadellid prey on lime (Tilia×vulgaris Hayne)

• 1 The paper describes the behavioural interactions between searching larvae of Adalia bipunctata and its aphid and cicadellid prey on lime (Tilia×vulgaris Hayne).
• 2 The frequency with which the predator achieves contact with cicadellid nymphs of differing ages is related to direction of predator approach and predator perception by the cicadellid.
• 3 The success of a coccinellid in contacting and capturing its aphid prey is related to the predator's size and direction of approach, the perception of the predator by an aphid and the latter's ability to escape, the effectiveness of which is discussed.

     

The invasive alien leaf miner Cameraria ohridella and the native tree Acer pseudoplatanus: a fatal attraction?

• 1 The horse‐chestnut leaf miner Cameraria ohridella is an invasive moth in Europe and a serious pest of horse‐chestnut Aesculus hippocastanum. The moth also occasionally attacks sycamore maple Acer pseudoplatanus, when situated beside infested horse‐chestnuts.
• 2 The main objective of the present study was to provide an overview of the relationship between C. ohridella and A. pseudoplatanus and to determine whether C. ohridella has the potential to shift to this native tree.
• 3 In the field, females oviposit on different deciduous tree species. Although less frequently attacked than A. hippocastanum, A. pseudoplatanus was clearly preferred for oviposition over 12 other woody species investigated.
• 4 Surveys in Europe demonstrated that the majority of A. pseudoplatanus trees found beside infested A. hippocastanum had mines of C. ohridella, even though more than 70% of the larvae died within the first two instars. Attack rates and development success greatly varied from site to site. Attack levels on A. pseudoplatanus were not always correlated with those on A. hippocastanum, and mines on A. pseudoplatanus were sometimes observed beside weakly‐infested A. hippocastanum.
• 5 Field observations, experimental exposure of A. pseudoplatanus saplings and rearing trials in a common garden study showed that individual trees may vary in their susceptibility to C. ohridella, whereas there was no evidence that C. ohridella populations vary in their performance on A. pseudoplatanus.
• 6 To date, there is little evidence that C. ohridella represents a major risk for A. pseudoplatanus.

     

Did the parasitoid Pnigalio mediterraneus (Hymenoptera: Eulophidae) track the invasion of the horse chestnut leafminer?

How communities of natural enemies, such as parasitoids, adapt to the range expansion of their hosts or the arrival of a novel invasive host is an important question in invasion biology. Do parasitoids track the expansion of their hosts from their shared native range? Do they locally adapt both behaviorally and physiologically to the arrival of a novel species by shifting hosts? Few studies have addressed those questions, yet they are important to develop efficient methods to manage invasive species. Here we focus on Pnigalio mediterraneus Ferriére and Delucchi (Hymenoptera: Eulophidae), an important parasitoid of two major agricultural and ornamental pests, the olive fruit fly Bactrocera oleae Rossi (Diptera: Tephritidae) and the horse chestnut leafminer Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae). C. ohridella recently invaded Europe starting from the Southern Balkans, whereas B. oleae has been associated since the Quaternary with wild olives in the Mediterranean, where it largely spread after the domestication of cultivated olives. We used two markers, the ribosomal spacer ITS2 and the mitochondrial gene COI. Although the ITS2 dataset provided little variation and no phylogeographic signal, analysis of mtDNA of 188 individuals of P. mediterraneus from 54 European localities allowed us to identify 53 haplotypes. Both nucleotide and haplotype diversity were higher for Mediterranean samples, and from samples reared from B. oleae. The statistical parsimony network identified one haplotype as the most frequent, ancestral and mainly associated with C. ohridella. Our findings suggest that P. mediterraneus locally host switched to C. ohridella from other hosts in the Balkans and later tracked the horse chestnut leafminer invasion over Europe. Therefore both host-tracking and ecological sorting could explain the current distribution of P. mediterraneus haplotypes.     

Invasion by the chestnut gall wasp in Italy causes significant yield loss in Castanea sativa nut production

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Sexually transmitted disease in a promiscuous insect, Adalia bipunctata

Abstract.

• 1 Sexually transmitted diseases (STDs) have rarely been reported in insects and other invertebrates. The majority of those reported involve organisms where sexual transmission is augmented by either vertical (i.e. inherited) transmission, or horizontal transmission, independent of host sexual activity.
• 2 We here demonstrate the existence of an STD in the coccinellid beetle Adalia bipunctata. This species bears a parasitic mite of the genus Coccipolipus. We show that, like many other podapolipid mites, this mite is transmitted between host individuals at a high rate during copulation. It also appears to be transmitted at a low rate between non-copulating individuals.
• 3 We show that infected female A.bipunctata produced eggs at a reduced rate, and that the eggs produced by infected females have highly decreased viability. However, no effect of infection upon host longevity was observed.
• 4 The results are discussed in relation to the incidences of sexually transmitted disease in invertebrates in general, the causes of disease symptoms, and the importance of this disease in the evolution of A.bipunctata.

     

Abundance and biological parameters of psyllophagous coccinellids in pistachio orchards

The abundance of coccinellids on pistachio trees was monitored at both a cultivated pistachio plantation and a wild pistachio growing area in Rafsanjan, Iran. Eleven ladybird species were identified from planted pistachio trees with Adalia bipunctata (Linnaeus) and Oenopia conglobata contaminata (Menetries) the most abundant ladybirds. At the wild pistachio plantation site, 17 coccinellid species were collected, with Brumus undulatus Weise the most abundant ladybird, followed by A. bipunctata and O. conglobata contaminata. Three species of Coccinellidae were evaluated for their potential for biological control of the common pistachio psylla (CPP), Agonoscena pistaciae Burckhardt and Lauterer. Coccinella undecimpunctata aegyptica (Reiche), Exochomus nigripennis (Erichson) and Hippodamia variegata (Goeze) developed successfully on A. pistaciae nymphs and reproduced successfully. Development and reproduction of these ladybirds were also examined on an alternative prey, the cotton aphid Aphis gossypii Glover, the most abundant aphid species on herbal weeds in pistachio orchards. The highest intrinsic rate of natural increase (r_m value) was observed in C. undecimpunctata aegyptica, 0.22 and 0.23 when it was fed on A. pistaciae and A. gossypii Glover, respectively. In comparison, the lowest r_m values (0.12 and 0.13) were found in E. nigripennis on the CPP and cotton aphid diets, respectively. Exochomus nigripennis consumed the largest number of psyllid nymphs during larval period, while the adults consumed the lowest number of psyllid nymphs daily. Although eight psyllophagous coccinellid species were collected in colonies of the CPP on pistachio trees, they did not regulate psyllid numbers below damaging levels. At present, conservation should assume a central role in biological control strategies for this pest.     

Food consumption and utilisation by larvae of two coccinellid predators, Scymnus levaillanti and Cycloneda sanguinea, on cotton aphid, Aphis gossypii

This study was carried out under laboratory conditions at various temperatures to compare food consumption and efficiency of conversion of food to body mass for larvae of two coccinellid predators, Scymnus levaillanti Mulsant (Coleoptera: Coccinellidae) and Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), which differ in body size and feeding method. The consumption rate of each larval stage of both species increased with increasing temperature. The consumption rate for total development (from egg hatch to pupation) of S. levaillanti was found to be 22.9 aphids per day at 30°C. It was much higher for C. sanguinea (975.1 aphids per day at 25°C and 1066 aphids per day at 30°C). The larger species, C. sanguinea was more voracious at each temperature than the smaller species, S. levaillanti. The larvae of S. levaillanti, employing pre-oral digestion, were more efficient in converting food to body mass than larvae of C. sanguinea, which used chewing and sucking. The fourth instars of both species were less efficient in converting food to body mass than were their first three instars. It was concluded that body size and feeding method of coccinellid predators play an important role in food consumption and efficiency of conversion of food to body mass.