Natural enemies of the South American moth, Tuta absoluta, in Europe, North Africa and Middle East, and their potential use in pest control strategies

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided.     

Artificially applied plant volatile organic compounds modify the behavior of a pest with no adverse effect on its natural enemies in the field

The use of volatile organic compounds (VOCs) derived from plants to manipulate insect pest behavior can be applied in an integrated pest management strategy (IPM) using a combination of attractive and repulsive stimuli. The “push–pull” strategy was developed on this idea in order to disturb and modify the distribution and abundance of pests to protect crops and reduce the use of agrochemicals. This field experiment investigates, in a “push–pull” context using broccoli as a target crop and Chinese cabbage as a pull component, the stimulo-deterrent effect of five synthetic VOCs (dimethyl disulfide, linalool, geraniol, eucalyptol and citronellol) on the oviposition of the cabbage root fly Delia radicum. With the exception of linalool, all compounds tested had a significant effect in the field and eucalyptol showed the most promising results, reducing oviposition on broccoli by 45 %. Moreover, eucalyptol was the only VOC able to reduce the final infestation of D. radicum, i.e., the number of pupae. The other VOCs reduced oviposition by 20–30 %. No adverse effect of the treatments was found on major parasitoids (Trybliographa rapae and Aleochara bipustulata) and potential predators of D. radicum. This study highlights the potential of VOCs as deterrent stimuli against agricultural pests in the field.     

Evaluating trap cropping strategies for insect pest control through simulation models

Trap cropping is a habitat management strategy where the aim is to reduce damage to the crop of interest by mixing it with other plants that are highly attractive to insect pests. However, despite its potential, the application of this strategy has been limited mainly due to a lack of consistent effectiveness. Here, we developed an individual-based spatially explicit model that accounts for reproduction, movement and mortality of insects within a mixed crop system. This model was used to evaluate the effects of varying trap crop spatial configurations (border, stripes and patches), cover (2, 4 and 10 %) and supplemental management strategies (early harvest and pesticide application) to gain insight into the best control options offered by trap cropping. As a case study, we considered Liriomyza huidobrensis, a world known leafminer pest. Our results showed a maximum reduction of about 34 % in the pest population of the main crop when using trap plants. The supplemental management strategy had a stronger effect than other factors, with pesticide use being the best option. A sensitivity analysis showed that demographic parameters were more relevant than the behavioral ones in determining the success of the method. Our model suggests that trap cropping is only suitable for controlling L. huidobrensis if a pesticide application is added to the trap crop. Individual-based models, which are cheaper and less laborious than direct field testing, might provide an important tool to help define management schemes for the control of herbivorous pests.     

Do the interactions among natural enemies compromise the biological control of the whitefly Bemisia tabaci?

The whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a worldwide pest which has become one of the main pests in tomato crops. The predators Macrolophus pygmaeus (Rambur) and Nesidiocoris tenuis Reuter (Hemiptera: Miridae) and the parasitoid Eretmocerus mundus (Mercet) (Hymenoptera: Aphelinidae) have shown their efficacy at controlling B. tabaci populations when used as biological control agents. Intraguild predation (IGP) between natural enemies can affect their effectiveness at controlling pests. In the present study, the interaction of these three natural enemies and their effect on B. tabaci was studied on tomato plants by combining morphological observations and molecular analysis of trophic interactions. Under the conditions used in the present study, no IGP was detected between M. pygmaeus and N. tenuis by either counting dead predators or by PCR using prey-specific cytochrome c oxidase I primers. However, predation on B. tabaci decreased when they coexisted on the same plant, which could compromise the biological control of this pest. Although PCR analyses using E. mundus-specific primers showed predation on B. tabaci-parasitized nymphs in 27 % of M. pygmaeus and 17 % of N. tenuis, B. tabaci control was improved when both predators coexisted on the same plant with the parasitoid. The combined use of E. mundus and M. pygmaeus/N. tenuis is therefore recommended in order to improve B. tabaci control in conservation biological control strategies.     

Birds as predators of cork and holm oak pests

The recent decline of Mediterranean oak woodlands in SW Iberian Peninsula is related to insect pests which affect both cork oak (Quercus suber) and holm oak (Quercus rotundifolia). We identified twenty-six bird species as potential regular predators of twenty major pests by reviewing the diet of breeding, wintering and resident species in this ecosystem. Foraging guilds are strongly associated with predation at distinct stages of the pests’ life-cycle: ground-foragers prey on overwintering pupae and larvae of seed-borers, tree-foragers prey on eggs, larvae and pupae of defoliating and wood-boring pests, and aerial-sweepers prey on airborne imagines. Bird predation can cover the complete life-cycle of pest species because different species may be complementary due to a dissimilar exploitation of foraging niches and periods. Small generalist tree-foraging passerines are important pest predators given their high densities and widespread distribution in Mediterranean oak woodlands, but management practices can have a significant negative effect in their populations.     

Effective biological control of an invasive mealybug pest enhances root yield in cassava

Insects provide critical ecosystem services to humanity, including biological control of pests. Particularly for invasive pests, biological control constitutes an environmentally sound and cost-effective management option. Following its 2008 invasion of Southeast Asia, biological control was implemented against the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) through the introduction and subsequent release of the host-specific parasitoid Anagyrus lopezi (Hymenoptera: Encyrtidae) in Thailand. In this study, we quantify yield benefits of mealybug biological control in Thailand’s cassava crop by using two different types of manipulative field trials: i.e., ‘physical exclusion’ cage trials and field-level ‘chemical exclusion’ assays. In cage trials with two popular cassava varieties, root yield and total dry matter (or ‘biological yield’) were a respective 4.0–4.2 times and 3.5–3.9 times higher in the presence of biological control. Extrapolating results from cage trials, biological control thus ensured an approximate yield gain of 5.3–10.0 T/ha for either variety. Under chemical exclusion trials, P. manihoti populations attained levels of 3266?±?1021 cumulative mealybug-days (CMD) over a 10-month time period, and no longer impact yields. Moreover, under effective P. manihoti control, both root yield and biological yield increased with season-long CMD measures, and pest management interventions-including insecticide sprays-led to notable reductions in yield. This study is the first to show how biological control effectively downgrades the globally invasive P. manihoti to non-economic status and restores yields in Thailand’s cassava crop. Our work emphasizes the economic value of biological control, reveals how current P. manihoti populations do not necessarily cause yield penalties, and underlines the central importance of nature-based approaches in intensifying global agricultural production.     

A review of Sorghum insect problems in Australia

The insect pests attacking grain sorghum in Australia are reviewed. For easy handling the insects are grouped according to the stages in plant growth which they attack, e. g. pests of the planting and seedling stages, pests of the vegetative stage, pests of flowering stage and pests of the maturity stage. Reference is made to the importance of storage pests. The adoption of minimum tillage practices in Australian summer cropping areas, the importance of soil insects during establishment stage of the crop is expected to increase. The sorghum midgeContarinia sorghicola (Coquillet) no doubt is the most damaging pest species.Heliothis armigera (Hübner) is second in importance to sorghum midge as a pest of sorghum. Damage and control methods of this and other pests are discussed. Economic injury levels are also discussed.     

Predation of lowbush blueberry insect pests by ground beetles (Coleoptera: Carabidae) in the laboratory

Agriculture relies on ecosystem services, such as biological control of pests, for economic success and sustainability. Commercially managed lowbush blueberries are an important crop in eastern North America, but pest control by natural enemies has not been well studied. In this paper we address questions about consumption of two blueberry pests by ground beetles (Carabidae) that are common in blueberry fields. In the first experiment, a Poecilus l. lucublandus, Carabus nemoralis, or Pterostichus mutus beetle was placed with two blueberry spanworm larvae, Itame argillacearia, in a simple (cup only or cup + soil) or more complex (cup + soil + blueberry sprigs) treatment arena. In most cases, probability of spanworm consumption reached 100 % in simple arenas by the end of the experiment (48 h) but was 25–50 % lower in more complex arenas. In a second experiment, a male or female Pterostichus melanarius or Harpalus rufipes beetle was placed in a plastic container with saturated or dry soil into which mature blueberry maggots, Rhagoletis mendax, dropped from blueberries to pupate. Approximately 40–80 and 35 % fewer pupae were recovered when a P. melanarius and H. rufipes beetle was present, respectively, but soil moisture and beetle sex were not significant factors. Our results demonstrate that ground beetles can prey upon important blueberry pests, but suggest that consumption may be influenced by microhabitat structure.     

Insect pest problems in tropical agroforestry systems: Contributory factors and strategies for management

Agroforestry trees are attacked by a wide spectrum of insects at all stages of their growth just like other annual and perennial crops. Pest management in agroforestry has not received much attention so far, but recent emphasis on producing high value tree products in agroforestry and using improved germplasm in traditional systems, and emergence of serious pest problems in some promising agroforestry systems have increased awareness on risks posed by pests. Insects may attack one or more species within a system and across systems in the landscape, so pest management strategies should depend on the nature of the insect and magnitude of its damage. Although greater plant diversity in agroforestry is expected to increase beneficial arthropods, diversity by itself may not reduce pests. Introduction of tree germplasm from a narrow genetic base and intensive use of trees may lead to pest outbreaks. In simultaneous agroforestry systems, a number of factors governing tree—crop—environment interactions, such as diversity of plant species, host range of the pests, microclimate, spatial arrangement and tree management modify pest infestations by affecting populations of both herbivores and natural enemies. Trees also affect pest infestations by acting as barriers to movement of insects, masking the odours emitted by other components of the system and sheltering herbivores and natural enemies. In sequential agroforestry systems, it is mostly the soil-borne and diapausing insects that cause and perpetuate damage to the common hosts in tree—crop rotations over seasons or years. An integrated approach combining host-plant resistance to pests, exploiting alternative tree species, measures that prevent pest build up but favour natural enemies and biological control is suggested for managing pests in agroforestry. Species substitution to avoid pests is feasible only if trees are grown for ecological services such as soil conservation and low value products such as fuelwood, but not for trees yielding specific and high value products. For exploiting biological control as a potent, low cost and environmentally safe tool for pest management in agroforestry, research should focus on understanding the influence of ecological and management factors on the dynamics of insect pest-natural enemy populations. Scientists and policy makers in national and international institutions, and donors are urged to pay more attention to pest problems in agroforestry to harness the potential benefits of agroforestry.This revised version was published online in November 2005 with corrections to the Cover Date.     

Abies religiosa forests harbor the highest species density and sporocarp productivity of wild edible mushrooms among five different vegetation types in a neotropical temperate forest region

More than 300 wild edible mushrooms are consumed in Mexico. They have been reported mainly from temperate forests in the center and southeast of the country. However, these valuable non-timber forest products are under-utilized because a lack of knowledge on their ecology and productivity. The objectives of this work were to compare the richness and fruit body production of wild edible mushrooms in temperate forests with a distinct vegetation composition in Amanalco, to describe species availability, and to test a new sampling approach in a heterogeneous environmental context. We designed a sampling method with random transects rather than traditional fixed sampling sites. Our method permits the acquisition of data from the highest number of environmental conditions. In 2009 and 2010, we collected and counted mushrooms in 248 transects distributed in five vegetation types (Abies, Abies–Pinus, Pinus, Pinus–Quercus and Quercus). We calculated the ecological importance value of each species as a function of its relative abundance and relative spatial frequency and relative temporal frequency. Abies religiosa pure stands and A. religiosa–Pinus forests had the greatest richness of edible fungi (43.1 and 21.3 species ha^?1, respectively) and produced most of the fruit bodies (1,160 and 820 ha^?1, respectively). The most abundant species in Amanalco region (combining all the vegetation types), Clavulina cinerea, Clitocybe gibba and Russula brevipes, also had the highest ecological importance value (0.2312, 0.1709 and 0.1516, respectively). These temperate forests maintain a considerable diversity of valuable wild edible mushrooms that are heterogeneously distributed according to the type of vegetation.     

Assessment of a commercial spider venom peptide against spotted-wing Drosophila and interaction with adjuvants

Chemical control of insect pests in food crops is dominated by broad-spectrum insecticides from a few classes, and there is an urgent need for alternative modes of action. We examined the efficacy of a spider venom peptide, GS-omega/kappa-Hxtx-Hv1a (hereafter, Hv1a) for control of spotted-wing Drosophila and evaluated the importance of phagostimulants and adjuvants for its efficacy. Topical and residual activity of Hv1a was low, with only 17.5% of exposed adult D. suzukii dying after 72 h. In contrast, 100% adult mortality was observed after 24 h when three adjuvants were added to Hv1a. Survival of eggs of D. suzukii oviposited into blueberries was also reduced by exposure to Hv1a combined with the same adjuvants, indicating that Hv1a activity against D. suzukii in the laboratory, but requires penetration of the insect cuticle for efficacy. In a field trial in blueberries, Hv1a gave comparable control to phosmet, and significantly reduced infestation in fruit. This biopesticide adds a new mode of action to the options available for integrated pest management of this and other insect’s pests.     

Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

Low-input farming is an alternative production system that provides a great opportunity to disentangle the natural mechanisms regulating crop pests, since neither pests nor their natural enemies are disrupted by pesticides. Here, we use a key apple pest in Europe, the apple blossom weevil (Anthonomus pomorum), as a model case to unravel the factors driving pest infestation and its biological control in a low-input context, namely the cider apple orchards of NW Spain. We applied a holistic approach based on the complete life cycle of the pest and combined large-scale observation (23 orchards) with small-scale experimental assessment. Weevil attack (0.4–37.4% of flowers) increased with the proportion on apple trees in the immediate orchard neighbourhood and with semi-natural woody habitat in the surrounding landscape and decreased with tree distance to orchard edge and apple bloom level. Thus, the prevalence of the pest depended on the availability of the various resources required for foraging, egg-lying and overwintering. Three types of natural enemies supplied complementary pest control by preying on weevils at different stages in their life cycle: seven parasitoid species attacked immature weevils (6.4–81.5%), while the additive effects of birds and crawling arthropods were evident in terms of the removal of adult weevils (31–44%). We conclude that the effective biological control of A. pomorum can be achieved in low-input systems to maintain the pest at non-harmful levels, through combined management of the pest, its habitat and its natural enemies.     

Influence of the surrounding landscape on the colonization rate of cereal aphids and phytovirus transmission in autumn

Ecological control has often focused on factors enhancing control of pests by their natural enemies, while factors reducing the colonization rate of crops by pests have been comparatively neglected. We present an approach to assess landscape influence on the intensity of wheat colonization by a major crop pest, the aphid Rhopalosiphum padi. We used trays containing wheat seedlings to monitor field colonization by R. padi and barley yellow dwarf viruses’ transmission in two areas in France in autumn. We assessed the influence of landscape components likely affecting aphid colonization, i.e. maize and grasslands as source of migrants on the number of aphids landing per tray, as well as the host plant of origin and the viruliferous potential of migrants. During the survey, maize was the main source of migrants. Virus transmission was detected in a few cases (4 % positive assays). Colonization was increased by the presence of maize, but reduced by the presence of grasslands at the landscape scale considered here (i.e. at a radius of 1000 m). Our study contributes to a better understanding of disease dynamics in agricultural landscapes. By identifying features of the landscape that surrounds fields and affects these dynamics, growers can develop more efficient crop protection strategies relying on habitat manipulation and rational use of pesticides.     

The molecular identification and genetic diversity of economically important wireworm species (Coleoptera: Elateridae) in Canada

Click beetle larvae (wireworms) are significant crop pests in Europe and North America. In Canada, there are ~30 economically important species which are morphologically difficult to identify, but for which sequence data are lacking. Accurate knowledge of damage-causing species and the population genetics and phylogeography of elaterids will provide insight into their sustainable management. Here, we use interspecific variation in mitochondrial 16S rRNA as a robust method of identification, consider the intra- and interspecific genetic variation of some important Canadian wireworm pests and assess the genetic structure and isolation by distance for a re-emerging major pest species, Hypnoidus bicolor Eschscholtz. Wireworms were sampled from Canada and the USA, identified as morphospecies, and sequenced at the 16S rRNA region (294–442 bp). Within some species unusually high intraspecific genetic distances between samples suggested the possibility of cryptic wireworm species or misidentifications, though this was <1 % for most species. Phylogenetic analyses gave some indication of the likely identity of these ambiguous samples. There was a significant correlation between genetic and geographic distance and significant genetic structuring within and between H. bicolor populations, which appeared to be composed of two species comprising several haplotypes. These data provide a starting point for determining the distribution of damage-causing species throughout Canada. The inclusion of data from other nuclear and mitochondrial loci, and use of sequence data from known adult samples, would further aid identification and relationships of wireworm species.     

MA-chitosan nanogel loaded with Cuminum cyminum essential oil for efficient management of two stored product beetle pests

Natural essential oils have received increased attention as alternatives to synthetic pesticides for pest management of foodstuffs. Recently, microencapsulation and other controlled release techniques are used to increase insecticidal efficiency and persistence of essential oils with slow and controlled release. In this study, the possibility of improving the insecticidal activity of plant essential oils was investigated for effective management of two stored product beetle pests. Self-assembly technique was used to prepare nanogels of myristic acid-chitosan loaded by essential oil extracted from cumin, Cuminum cyminum L. Fumigant toxicity of C. cyminum oil and oil-loaded nanogels (OLNs) were investigated at 4, 7, 10, 13, and 16 µL/L air against the granary weevil Sitophilus granarius L. and 8, 11, 14, 17, and 20 µL/L air for confused flour beetle Tribolium confusum Jacquelin du Val. Experiments were conducted at 27 ± 1 °C and 55 ± 5 % relative humidity in continuous darkness. Insecticidal bioassay revealed that OLNs were more toxic than C. cyminum oil against tested beetle pests. The persistence of the oil and OLNs was also evaluated against two tested species. Results indicated that C. cyminum oil completely lost its insecticidal activity after 12 days, whereas at the same period, the OLNs lost about 60 % of its activity when applied against S. granarius and 15% for T. confusum. Therefore, it could be concluded that encapsulation improved the persistence of the oil.     

Using flower strips to promote green lacewings to control cabbage insect pests

Habitat management improves biological control by increasing the abundance and fitness of natural enemies through the provision of floral resources along field edges or between crops. Among the natural enemies reliant on flower resources, green lacewings often stand out due to their abundance, predation capacity and polyphagy. We evaluated the impact of tailored flower strips on the enhancement of natural enemies, especially green lacewings, in three organic cabbage (Brassica oleracea) farms in Southern Sweden. Insects were sampled from the flower strips, and cabbage pests and predators were visually recorded in the crop. In a laboratory assay, the pollen feeding preferences of Chrysoperla carnea (Stephens, 1836) were evaluated in a dual-choice test. The pollen consumed by the Chrysopidae was extracted from laboratory and field specimens, then quantified and identified. Flower strips were found to attract predators and parasitoids, whose abundance increased as flowers bloomed. Cabbage plants next to the flower strips showed lower pest infestation as compared to cabbage plant control, although no significant differences were observed in the number of predators. Chrysopidae used flower strips as feeding, reproduction and shelter sites and mainly consumed pollen from Phacelia tanacetifolia Benth. Under laboratory conditions, C. carnea showed a preference for P. tanacetifolia and Coriandrum sativum L. pollen over Borago officinalis L. and Fagopyrum esculentum Moench. We show that tailored flower strips could be an efficient tool for enhancing beneficial arthropods and should be considered in integrated pest management for cabbage crops.

     

Eco-label credibility and retailer effects on green product purchasing intentions

Eco-labels offer an identifiable marketing tool to convey a product's environmentally friendly and socially desirable characteristics to final consumers. Furniture offers a prime example of the opportunities and challenges to the expansion of green products. This study examined how eco-label credibility and retailer type affect green purchasing intentions (GPIs). Data from a sample of final consumers collected across 124 cities in China were analyzed using a Bayesian approach. Consumers who purchase furniture at supermarkets exhibited a lower GPI compared with consumers at other furniture retailers, ceteris paribus. Consumer perceived credibility of eco-labels, past green purchase, awareness of green furniture, level of education, and whether there is an elder family member in household were all found to positively affect consumers' GPI. Eco-labels may bring market opportunities for green furniture manufacturers but these are limited by effective communication and product outlets. It is intrinsic for green furniture manufacturers to choose retailers with a positive reputation among final consumers to improve credibility and potentially expand market share.     

Soil insect pests of cold temperate zones of East Asia,including DPR Korea: A review

Food crops have come under increasing threat from soil insect pests as a result of monotonous use of arable land and the unavailability or ban of soil insecticides. The development of new management strategies is hindered by the limited knowledge of the identity and biology of local soil pests. A literature survey was carried out focusing on the cold temperate zones of East Asia (north-eastern China, far south-eastern Russia, both Koreas). As for DPR Korea, field surveys were added. At least 53 soil insect species appeared to have wide-ranging importance. The highest diversity of soil pests attack maize (at least 29 species), cereals (27), soybean (19), potato (19), other beans (16), peanut (16), fruit tree nurseries (14), followed by cabbage, sorghum, cotton, grassland habitats, and sweet potato. Most belong to the Melolonthidae (21 %), Scarabeidae (15 %), Noctuidae (13 %) or Elateridae (11 %). Genera containing the most species were the melolonthid Holotrichia (at least five species), scarabeid Anomala (5), agromyzid Delia (4) and noctuid Agrotis, melolonthid Maladera, and gryllotalpid Gryllotalpa (each three). Below-ground damaging pests appeared widely problematic across the cold temperate zones, probably due to the limited variety of crops suitable for rotation or strip cropping, and efficient adaptation of pests to the soil environment as a result of long overwintering periods. This review will, as a result of making some of a vast repository of non-English language information available, help to better understand the soil pest community in these regions, and support the development of more effective control methods.     

Über landwirtschaftliche und soziologische Einflüsse auf das Auftreten und die Bekämpfung von Schädlingen in Saudi-Arabien

In former times there were only small cultivation areas in Saudi Arabia consisting of native crop varieties which were large resistant to pests and diseases. They showed an ecologic equilibrium. Since then modern technics and irrigation resulted in a considerable enlargement of these areas which are now attacked by many pests. The most important of the mite and insect pests are reviewed. In Agric. and Water Res. Center of Riyadh scientists are building up an extensive collection of all arthropods living in Saudi Arabia. For the purposes of pest control efforts are made to reach an integrated pest management. Studies are going to reduce the damages by help of cultivation measures.