A novel prospect for an oviposition attraction of Chrysoperla carnea (Steph.) (Neuroptera: Chrysopidae) for its population upsurge

Common green lacewings (Chrysoperla carnea species complex) are important predators of several insect pests, particularly aphids. Due to their potential in biological control, several efforts have been made to find means to retain common green lacewing adults or even to increase their numbers at a given site. In the course of field experiments conducted in Hungary and Norway, we tested the effect of a known ternary bait (phenylacetaldehyde, methyl salicylate, acetic acid) on oviposition and overwintering site choice of common green lacewings. In an orchard in Hungary, overwintering chambers were set up with and without baits. For the experiment on oviposition in Norway, a number of lacewing eggs were compared on trees with and without baits in selected sectors of the canopy. With the ternary bait, more common green lacewings could be attracted to overwintering chambers, and also significantly more eggs were found in the vicinity of baits than in other selected parts of the canopy, suggesting that this bait has the potential to manipulate both overwintering site choice and oviposition site choice of these important beneficial insects.

Gulløyelarver (green lacewing larvae, Chrysoperla carnea) is a product for biological control. The application is for use against aphids in green-houses and tunnels.
 Gulløyelarver was used in Norway from 1985-1993. An assessment in 2001 concluded however that the use of products with Chrysoperla carnea could represent an environmental risk since it was not known if the species in the products were the same as the ones with natural occurrence in Scandinavia.
 In this regard, The Norwegian Food Safety Authority would like VKM to perform an assessment of possible risks related to health and environment in light of possible new data.
 VKM’s conclusions are as follows:
 Health:
 The larvae of Chrysoperla carnea have hollow jaws through which they can inject digestive enzymes into their prey. In contact with humans, the larvae are capable of delivering painful bites which may cause local swelling. Such bites are however not considered dangerous, and can be avoided with preventive measures.
 Allergic asthma and rhino conjunctivitis has been reported in persons working in the production of biological agents with Chrysoperla carnea, but it is the opinion of VKM that such effects are not likely to be relevant for users of the agents.
 Environment:
 A previous assessment in 2001 concluded that the use of products with Chrysoperla carnea represented an environmental risk because of the risk of genetic interference with natural populations of the species in Norway.
 Lacewings belonging to the Chrysoperla carnea complex are considered established and indigenous in Norway, and a recent study by the Norwegian Institute for Agricultural and Environmental Research (Bioforsk) strongly suggests that the lacewings in the commercial products belong to the same cryptic species complex as individuals sampled in Norway. In case the species in the products is different from those present in Norway, any genetic interference with local populations in Norway is prevented by differences in duetting songs.
 If an invertebrate biological control agent is indigenous and has limited direct or indirect effect on the environment, it is the opinion of VKM that it could be authorized for release in greenhouses or plastic tunnels.
 Chrysoperla carnea is polyphagous and cannibalistic. They prefer aphids, but may also consume other insects and mites. It is however the opinion of VKM that the environmental risk from this will be minimized in greenhouses and tunnels where the release will be in a contained environment and directed against aphid colonies.
 Establishment, host range and dispersal ability should be carefully reviewed, even if the species is indigenous. Chrysoperla carnea may establish in the greenhouse and plastic tunnels and may also possess the ability to disperse and survive in the field. However, it is the opinion of VKM that the direct and indirect effects of this are at most moderate, although it cannot be completely excluded that Chrysoperla carnea species in the products might also have properties that have not been reviewed.

Simple SummaryBacteria have occupied a wide range of habitats including insect hosts. There they can strongly affect host physiology and ecology in a positive or negative way. Bacteria living exclusively inside other organisms are called endosymbionts. They often establish a long-term and stable association with their host. Although more and more studies focus on endosymbiont–insect interactions, the group of Neuroptera is largely neglected in such studies. We were interested in the common green lacewing (Chrysoperla carnea), a representative of Neuroptera, which is mainly known for its use in biological pest control. We asked ourselves which endosymbionts are present in these lacewings. By screening natural and laboratory populations, we found that the endosymbiont Rickettsia is present in all populations but the symbiont Sodalis only occurred in laboratory populations. We were curious whether both endosymbionts affect reproduction success. Through establishing and studying green lacewing lines carrying different endosymbionts, we found that Rickettsia had no effect on the insect reproduction, while Sodalis reduced the number of eggs laid by lacewings, alone and in co-infections with Rickettsia. The economic and ecological importance of green lacewings in biological pest control warrants a more profound understanding of its biology, which might be strongly influenced by symbionts.Endosymbionts are widely distributed in insects and can strongly affect their host ecology. The common green lacewing (Chrysoperla carnea) is a neuropteran insect which is widely used in biological pest control. However, their endosymbionts and their interactions with their hosts have not been very well studied. Therefore, we screened for endosymbionts in natural and laboratory populations of Ch. carnea using diagnostic PCR amplicons. We found the endosymbiont Rickettsia to be very common in all screened natural and laboratory populations, while a hitherto uncharacterized Sodalis strain was found only in laboratory populations. By establishing lacewing lines with no, single or co-infections of Sodalis and Rickettsia, we found a high vertical transmission rate for both endosymbionts (>89%). However, we were only able to estimate these numbers for co-infected lacewings. Sodalis negatively affected the reproductive success in single and co-infected Ch. carnea, while Rickettsia showed no effect. We hypothesize that the fitness costs accrued by Sodalis infections might be more tolerable in the laboratory than in natural populations, as the latter are also prone to fluctuating environmental conditions and natural enemies. The economic and ecological importance of lacewings in biological pest control warrants a more profound understanding of its biology, which might be influenced by symbionts.

Immature development of the common green lacewing, Chrysoperla (= Chrysopa ) carnea Stephens, requires 20.5, 21.6, and 24.9 d at 27°C, with a photoperiod of 16:8 (L:D), when fed Ostrinia nubilalis (Hubner) (European corn borer) eggs, Agrotis ipsilon Hufnagel (black cutworm) eggs, and A. ipsilon neonates, respectively. Twenty-six to 40% of the individuals died when reared on eggs, 65% died when reared on A. ipsilon neonates, and all died when fed O. nubilalis neonates. Mortality of Chrysoperla carnea larvae on O. nubilalis neonates was due to entanglement in the silk produced by these larvae. An average of 377 ± 7 O. nubilalis eggs, 641 ± 43 A. ipsilon eggs, and 2,056 ± 148 A. ipsilon neonates were preyed upon by Chrysoperla carnea during larval development. Chrysoperla carnea and Chrysopa oculata Say first instars were unable to survive on stalk borer, Papaipema nebris (Guenee), eggs. More than 80% of Chrylsopa oculata larvae, reared on corn leaf aphids, Rhopalosiphum maidis (Fitch), as first and second instars and then switched to P. nebris eggs died as third instars, whereas only 30% of similarly reared Chrysoperla carnea third instars died. The most suitable prey, resulting in the fastest development with highest survival, for Chrysoperla carnea were O. nubilalis and A. ipsilon eggs; R. maidis was most favorable for Chrysopa oculata .

Seven spot ladybird beetle, (Coccinella septempunctata) is a widely distributed natural enemy of soft-bodied insect pests especially aphids worldwide. Both the adult and larvae of this coccinellid beetle are voracious feeders and serve as a commercially available biological control agent around the globe. Different techniques are adopted to enhance the mass rearing and storage of this natural enemy by taking advantage of its natural ability to withstand under extremely low temperatures and entering diapause under unfavorable low temperature conditions. The key objective of this study was to develop a cost effective technique for enhancing the storage life and predatory potential of the larvae of C. septempunctata through cold storage in conjunction with the use of nuclear techniques, gamma radiations. Results showed that the host eating potential of larvae was enhanced as the cold storage duration was increased. Gamma irradiation further enhanced the feeding potential of larvae that were kept under cold storage. Different irradiation doses also affected the development time of C. septempuntata larvae significantly. Without cold storage, the lower radiation doses (10 and 25 GY) prolonged the developmental time as compared to un-irradiated larvae. Furthermore, the higher dose of radiation (50GY) increased the developmental time after removal from cold storage. This study first time paves the way to use radiation in conjunction with cold storage as an effective technique in implementation of different biological control approaches as a part of any IPM programs

Paper presents a larval cannibalism of green lacewings (Chrysoperla carnea), which was observed during the laboratory bioassay on non-target effect of entomopathogenic nematodes against green lacewings larvae. The most probable reason for larval cannibalism were undersized Petri dishes in which the bioassay was performed. Due to large number of larvae per surface unit, frequent crossing of green lacewings larvae appeared and this consequently lead to cannibalism. In most cases larger, elder larvae consumed smaller, younger larvae. Cannibalism increased with temperature rise and was the most intensive at 25 °C. At this temperature the larval mortality was 22.0 % after two days, while after four days the larval mortality reached 31.0 %.

Paper presents a larval cannibalism of green lacewings (Chrysoperla carnea), which was observed during the laboratory bioassay on non-target effect of entomopathogenic nematodes against green lacewings larvae. The most probable reason for larval cannibalism were undersized Petri dishes in which the bioassay was performed. Due to large number of larvae per surface unit, frequent crossing of green lacewings larvae appeared and this consequently lead to cannibalism. In most cases larger, elder larvae consumed smaller, younger larvae. Cannibalism increased with temperature rise and was the most intensive at 25 °C. At this temperature the larval mortality was 22.0 % after two days, while after four days the larval mortality reached 31.0 %.

Simple SummaryBaculoviruses (BV) infect several lepidopteran pests of economic importance, such as the beet armyworm Spodoptera exigua. The joint use of microbiological and macrobiological strategies may improve the efficacy of control. Laboratory bioassays were developed to evaluate the interactions between two BVs: the multiple nucleopolyhedroviruses of S. exigua (SeMNPV) and Autographa californica (AcMNPV), and the predator Chrysoperla carnea. The excretion products of the predator’s larvae (drops) and adults (meconia) were microscopically examined after the ingestion of BV-infected S. exigua larvae. For both types of excreta and BVs, viral occlusion bodies (OBs) (resistance forms) were observed. These OBs were infective to healthy S. exigua larvae when applied in water suspension and in direct deposition. The virulence of meconia was higher in suspensions (higher viral load), while larval drops were more virulent in direct application due to their liquid nature and their easiness of consumption. The fitness of C. carnea was slightly affected by the consumption of both BV-infected prey. No preference was shown between healthy and BV-infected S. exigua, and both were preferred vs. the aphid Macrosiphum euphorbiae. Our findings present C. carnea, and particularly its larvae, as a promissory candidate for BV dispersion in the field.Baculoviruses (BV) are highly effective against lepidopteran pests of economic importance such as Spodoptera exigua. The combined use of entomopathogens and macrobiological control agents requires the study of their relationships. Laboratory bioassays were developed to evaluate the interactions between the multiple nucleopolyhedroviruses of S. exigua (SeMNPV) and Autographa californica (AcMNPV), and the predator Chrysoperla carnea. The microscopic examination of predator’s excreta (larval drops and meconia) after the ingestion of BV-infected S. exigua revealed the presence of viral occlusion bodies (OBs). The reinfection of S. exigua larvae with BVs-contaminated excreta by using OBs water suspensions or by direct application both yielded high mortality values but different speed-of-kill results. Meconia killed before in suspensions due to their higher viral load and larval excretion drops did so in direct application due to their liquid nature and their easiness of consumption. The prey-mediated ingestion of SeMNPV and AcMNPV triggered slight effects in C. carnea, which were probably derived from the food nutritional quality. Chrysoperla carnea larvae did not discriminate between healthy and BV-infected S. exigua, while a preference was shown for S. exigua (healthy or infected) vs. Macrosiphum euphorbiae. Our findings present C. carnea, and particularly its larvae, as a promissory candidate for BV dispersion in the field.

Species-specific differences in the responses of egg-laying mosquitoes (Diptera: Culicidae) to the presence of fish exudates in oviposition sites in laboratory bioassays have been related to the likelihood of encountering mosquito-eating fish in natural oviposition sites. We examined the responses of egg-laying mosquitoes to the presence of larvivorous fish in oviposition sites to test this hypothesis in the field. The number of Culex tarsalis Coquillett egg rafts laid on mesocosms (15.5 m2; 8 m3) containing caged mosquitofish (0.066 Gambusia affinis per liter) was reduced by 84% relative to mesocosms lacking fish. Egg-laying Culex quinquefasciatus Say did not differentiate significantly between comparatively small (0.11 m2) oviposition sites containing water conditioned with mosquitofish (0.3 G. affinis per liter) versus aged reservoir water. Cx. quinquefasciatus egg rafts were not collected from the larger mesocosms, and Cx. tarsalis egg rafts were rarely collected from the smaller oviposition sites. Oviposition preferences for characteristics of aquatic habitats that lack fish (e.g., small size, semipermanence, and high levels of organic enrichment in which hypoxic conditions are prevalent) may limit the coexistence of immature stages of some mosquito species such as Cx. quinquefasciatus and insectivorous fish. Mosquito species such as Cx. tarsalis that also use comparatively large water bodies as developmental sites may have evolved the ability to detect the presence of predatory fish.

In this study, natural mortality factors of Citrus Leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) were investigated under field conditions. The studies were carried out in a lemon orchard in Adana, Turkey during 2007-2008. Ten trees were selected and weekly one shoot from each tree, and a total of ten shoots, were collected randomly during May-November. In the laboratory, the first 15 leaves were checked using a binocular microscope. All biological stages of the pest and the parasitoids, dead or infected individuals, and empty mines, were counted. According to the method and symptoms of predation, the mortality factors of the pest were recorded. In 2007 and 2008, large numbers of larvae were parasitized (46.25% and 48.12%, respectively). The larval parasitoid Citrostichus phyllocnistoides Narayanan (Hymenoptera: Eulophidae) was the abundant species in both years. The third instar of the host had the highest percent of parasitized individuals. In the first year, 15.33% of the pest were consumed by spiders, 10.07% by Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) and 3.14% by ants, whereas in the second year these ratios were 16.61%, 8.57% and 3.78%, respectively. Second instar larvae were the most preferred stage for predation. In 2007, in 13.66% of the mines no pests were recorded, whereas the mortality source of 5.19% of the larvae and pupae was not detected. In 2008, these ratios were 10.21% and 6.87%, respectively. It was determined that predators are as effective as the parasitoids in the biological control of the pest.

Greenhouse and nursery studies were conducted to determine an optimal release rate and efficacy of green lacewing (glw) larvae, Chrysoperla carnea (Stephens), for suppression of azalea lace bug (alb), Stephanitis pyrioides (Scott). In a greenhouse study, different densities of lace bugs (40 or 80 per plant) did not influence the percent mortality caused by green lacewings. However, greater numbers of green lacewing larvae released resulted in higher lace bug mortality (5 and 20 glw per plant resulted in an average lace bug mortality of 79% and 97%, respectively). Lacewing larvae released in a production nursery, at rates of 5/plant and 10/plant, and acephate (Orthene) significantly reduced lace bug populations, with green lacewings at 10/plant and acephate reducing lace bug densities more than green lacewings at 5/plant. In a second nursery trial, lacewing larvae released into production blocks of azaleas resulted in a 97% reduction in lace bugs. These studies suggest that augmentative release of green lacewing larvae may provide an alternative control tactic that can be integrated into lace bug pest management programs.

Conservation biological control (CBC) is a promising tool for ecological intensification that aims to establish resilient natural enemy populations that contribute to pest management with reduced use of pesticides and at the same time support native biodiversity in agroecosystems. Yet the impact of natural enemies in CBC is often limited due to missing resources such as food, habitat, and hibernation shelters. Here, we studied a CBC strategy that incorporates these essential resources combined with semiochemicals, focusing on how the common green lacewing can enhance biological control of aphids.In a 4-year field study conducted at three locations in the region of East Norway, we developed a CBC strategy combining the three measures ATTRACT (a ternary attractant that increase lacewing egg laying), FOOD (floral buffer strips), and SHELTER (insect hotels for overwintering survival) to increase aphid biological control in spring barley. We recorded the number of lacewings, ladybirds, hoverflies, parasitized aphid mummies, and the two cereal aphid species Sitobion avenae and Rhopalosiphum padi. Our CBC strategy resulted in a significant increase in lacewing activity and significant aphid suppression. At all three locations and over the 4-year period, aphid infestation was below the economic damage threshold in the field plots using CBC measures. In contrast, during two of the years, the density of the aphid infestation in the control plots was significantly above the damage threshold. We found evidence that use of the ternary attractant supported green lacewings but led to loss of ladybirds, hoverflies, and parasitoids, even though flower strips were used as alternative resources.Our study shows a promising increase in lacewing activity in the agricultural landscape and high biological control of aphids in barley. Long-term field studies are needed to evaluate the impact on non-target species and the agroecosystem before practical application of this approach can be considered.

Influence of transgenic Bacillus thuringiensis corn-fed prey on prey preference of immature Chrysoperla carnea (Neuroptera: Chrysopidae)

BACKGROUND: Chemical pesticides are predominantly used for managing various pests on strawberries in California. Biological control is limited to the release of predatory mites against spider mites. Predominant use of chemical pesticides does not provide complete and satisfactory control of certain pests and interferes with biological control. Microbial control is an unexplored area in California strawberries. Limited pest control with current practices, risk of pesticide resistance, and concern for environmental safety associated with excessive use of chemical pesticides prompt the search for safer and effective alternatives. Entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin and a botanical pesticide, azadirachtin are active against most of the strawberry pests. Additionally, B. bassiana is known to endophytically colonize some plant species and provide protection against herbivore damage. Identifying non-chemical alternatives is a critical area in strawberry pest management. OBJECTIVE: Explore the potential of B. bassiana against strawberry pests and the ability to colonize strawberry plants. METHODS: Efficacy of reduced rates of chemical pesticides, B. bassiana, and azadirachtin against adult lygus bug, Lygus hesperus Knight were determined in laboratory assays. Greenhouse and laboratory studies were conducted to determine endophytic colonization potential of B. bassiana in strawberry plants. Efficacy of B. bassiana against L. hesperus was determined in small plot field trial in strawberries and against other pests in greenhouse strawberries was also studied. RESULTS: Certain combinations of chemical pesticides and B. bassiana at reduced rates improved L. hesperus mortality. Beauveria bassiana colonized and persisted in various strawberry tissues for up to 9 weeks after inoculation. No impact of the B. bassiana on L. hesperus numbers was seen in the field study, but was found effective, along with azadirachtin, against some pests in the greenhouse study. CONCLUSION: Non-chemical alternatives such as B. bassiana and azadirachtin have a good potential for strawberry pest management.

The utilization of olfactory responses of predators and ­parasitoids to the allelochemicals emitted by phytophagous arthropods and their host plants is becoming more important in biological pest control. The effects of three weed ­species, i. e. wormwood Artemisia vulgaris L., tansy Tanacetum vulgare L. and stinging nettle Urtica dioica L., which were planted as accompanying vegetations into a lettuce field, were examined for the predatory species Coccinella septempunctata L., Adalia bipunctata (L.), Propylea quatuordecimpunctata (L.) (Coleoptera, Coccinellidae) and Chrysoperla carnea (Steph.) (Neuroptera, Chrysopidae), as well as for aphids during the summer of 2000. The presence of weeds significantly increased the density of adults and larvae of the predators on the lettuce plants in relation to the control (lettuce field without weeds). However, the differences remained smaller for eggs and pupae. C. septempunctata tended to be the most abundant species, followed by P. quatuordecimpunctata. Remarkable differences among the attractiveness levels of the weeds in the 3 treatments were not observed. The increased populations of predators were accompanied by significantly reduced infestation rates with aphids in the treatments in relation to the control. Myzus persicae Sulzer was in general the most abundant aphid species followed by Nasonovia ribisnigri Mosley and Macrosiphum euphorbiae Thomas. The results of the present study are discussed with respect to the management of agroecosystems and the use of weeds in biological control.