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Abstract Background Macrolophus caliginosus Wagner is one of the most important polyphagous predatory mirid bug that attack many agriculture insect pests. Methods The present study was carried out to show the effect of different prey stages as Tuta absoluta (eggs and fourth larval stage), Bemisia tabaci (eggs and three nymph stages) and Aphids gossypii (1st nymph stage) on the life cycle and consumption rate of male and females of M. caliginosus as predator under laboratory condition. The experiments were started by collecting the first stage of M. caliginosus nymph and placed separately on acalypha plants situated on saturated cotton pads inside Petri dishes with an excess of each prey. Results The results showed that the developmental period of the total immature stages of M. caliginosus female are affected by type and stage of tested prey. So, the duration of larval stages of female was significantly recorded the longest in case of feeding on eggs of T. absoluta compare to 1st nymph of A. gossypii. In addition to extension the adult longevity of female M. caliginosus, which fed on the 1st nymphal instar of B. tabaci more than the other pests. The consumption rate of total immature stages and adult M. caliginosus female were fed on eggs of B. tabaci was more than the other test pests. While the consumption rate of total immature stages and adult of male M. caliginosus were fed on eggs of B. tabaci was higher than that of the other pests. Conclusions The search was given the highlight focus on ability of mirid bugs to consume different insect species “stages” that might be facilitate rear predatory bugs under laboratory condition.

Background: Macrolophus caliginosus Wagner is one of the most important polyphagous predatory mirid bug that attack many agriculture insect pests. Methods: The present study was carried out to show the effect of different prey stages as Tuta absoluta (eggs and fourth larval stage), Bemisia tabaci (eggs and three nymph stages) and Aphids gossypii (1st nymph stage) on the life cycle and consumption rate of male and females of M. caliginosus as predator under laboratory condition. The experiments were started by collecting the first stage of M. caliginosus nymph and placed separately on acalypha plants situated on saturated cotton pads inside Petri dishes with an excess of each prey. Results: The results showed that the developmental period of the total immature stages of M. caliginosus female are affected by type and stage of tested prey. So, the duration of larval stages of female was significantly recorded the longest in case of feeding on eggs of T. absoluta compare to 1st nymph of A. gossypii. In addition to extension the adult longevity of female M. caliginosus, which fed on the 1st nymphal instar of B. tabaci more than the other pests. The consumption rate of total immature stages and adult M. caliginosus female were fed on eggs of B. tabaci was more than the other test pests. While the consumption rate of total immature stages and adult of male M. caliginosus were fed on eggs of B. tabaci was higher than that of the other pests. Conclusions: The search was given the highlight focus on ability of mirid bugs to consume different insect species "stages" that might be facilitate rear predatory bugs under laboratory condition. [ABSTRACT FROM AUTHOR]

Abstract The present study was carried out in greenhouses, on sweet pepper crops, during the winter plantations 2015–2016 and 2016–2017 in a commercial farm located at Berkash district, Giza, Egypt. During the first season, three acariphagous biocontrol agent species, the predatory mite, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) (at a rate of 2 individuals/m2), and two of predatory insect, Macrolophus caliginosus Wagner (at a rate of 1 individual/m2) and Orius albidipennis (Reuter) (at a rate of 1/2 individual adults/m2), were applied to control Tetranychus urticae. The obtained results showed that T. urticae was controlled successfully using A. swirskii and O. albidipennis. Releasing of A. swirskii and O. albidipennis caused 26 and 24% yield increases, respectively, as compared to control treatment. During the second season of 2016–2017, the efficiency of O. albidipennis at a rate of 1/2 per m2 was compared to three recommended pesticides, for controlling T. urticae. The obtained results revealed that applying O. albidipennis proved to be the most efficient control method against T. urticae on sweet pepper, with the lowest remaining pest density of T. urticae (2.9 mites/leaf); while with chemical control, the remaining density of T. urticae reached 20.13 mites/leaf at the end of the season. Thus, results demonstrated that the released insect predator, O. albidipennis, was the most effective method to control T. urticae under greenhouse conditions for two reasons. On the one hand, it resulted in a 31.36% yield increase, and on the other hand, it could reduce the chemical application, to improve food safety and environmental pollution reduction.

Se presenta una revisión actualizada sobre heterópteros (Miridae) depredadores con potencial para el control biológico de mosquitas blancas, Macrolophus pygmaeus Rambur (anteriormente M. caliginosusWagner), y en particular Tupiocoris cucurbitaceus (Spinola) sobre la mosquita blanca Trialeurodes vaporariorum (Westwood) (Trialeurodidae) en plantas de tabaco y tomate de invernadero en la Región Metropolitana, Chile central.

Updated information has been revised and is presented on heteropteran (Miridae) predators with potential in biological control of whiteflies, Macrolophus pygmaeus Rambur (formerly M. caliginosus Wagner), and mostly on Tupiocoris cucurbitaceus (Spinola), which has been observed preying on the whitefly Trialeurodes vaporariorum (Westwood) (Trialeurodidae) on tobacco plants and greenhouse tomato in the Metropolitan region, central Chile. [ABSTRACT FROM AUTHOR]

Herbivore induced plant volatiles (HIPVs) can be produced by herbivores attack that affects on ecology and behavioural responses of natural enemies. Damaged plant attracts natural enemies due to change the volatile compounds constitute by an active biochemical processes. This study was conducted to test whether green bean HIPVs, as well as odours emitted directly from spider mites influenced the orientation behaviour of the predatory mirid bug, Macrolophus caliginosus Wagner. A Y-tube olfactometer was used to determine the attraction of the predator to herbivore induced volatiles from Tetranychus urticae Koch infested green bean plants over clean plants and to direct prey odours over clean air. The mirid bugs showed a stronger response to odours from infested plants than to those from clean plants. The mirids, however, did not seem to exploit odours emitted directly from the preys themselves. Compounds of infested and uninfested plant volatile blends were also determined by gas chromatography-mass spectrometry (GC-MS). Of a total of 36 infested green bean compounds, 29 compounds are emitted either by uninfested green bean. The results from GC-MS analysis confirm that volatile blends emanate from bean infested by spider mites is different to clean bean and the attractiveness of predatory mirid bugs to infested plant over clean bean is probably resulting in these differences.

The zoophytophagous mirid bug Macrolophus caliginosus is an important biocontrol agent of whiteflies in the Mediterranean region. Periods of low productivity in commercial breeding units and unsuccessful establishment in greenhouses prompted this study of mating behaviour. Here we describe copulation behaviour, the diel mating periodicity and post-copulatory refractory period. A natural plant substrate needs to be provided if one wants to observe the copulatory behaviour of M. caliginosus in the laboratory. There was no apparent directional orientation in the approach of the two sexes, instead males pursued females after "accidentally" contacting them. Males mounted females from above, very rapidly, and without any obvious courtship behaviour, and copulation duration was very consistent (286.33 ± 4.23 s, mean ± SE). Observations over a 24-h period showed that mating was most frequent in the 8-h scotophase and first half of the 16-h photophase than in the second half of the photophase. Mated females became strongly unreceptive to new male mounting attempts, shaking their abdomen and leaving the plant if harassed. To determine the duration of the post-mating refractory period mating receptivity of females that had mated 1 or 2 weeks earlier was compared with that of virgin females of similar age. Mated females remained unreceptive even 2 weeks after mating, whereas half of the virgin females of equivalent age mated. Mated females were more likely to abandon a plant than virgin females when harassed by a male. Most males remated a few minutes after mating for the first time. M. caliginosus is atypical among mirids in that females apparently mate only once.

The tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most devastating pests. It has become a serious threat to tomato production in Egypt. Five greenhouse trials were conducted on tomato crop during winter plantation of 2013-14 explored control strategies using the egg-parasitoid, Trichogramma achaeae Nagaraja and Nagarkatti (at a rate of 50 adults/m2), microbial control (using Bacillus thuringiensis at a rate of 2g/L) and the insect predator, Macrolophus caliginosus Wagner (at a rate of 1/2 adults/ m2) in a commercial tomato farm at Berkash district, Giza, Egypt, beside a combination of the three bioagents (T. achaeae, M. caliginosus and Bt) at a rate of 25 adults/m2, 1/4 adult /m2, 1g/ L, respectively. Obtained results showed that all treatments presented a highly significant efficatcy in reducing T. absoluta mines, especially the combination of the three bioagents. [ABSTRACT FROM AUTHOR]

Two Macrolophus species, M. melanotoma (=M. caliginosus) and M. pygmaeus, have been referred to as efficient predators of several key pests on vegetable crops in Europe. However, due to the great morphological similarity of these species, they have been confused, with important consequences for inoculative releases of these predators in greenhouses and for the conservation of their natural populations on greenhouse and outdoor crops. In this work, we developed tools to identify these morphologically very similar species. We first confirmed the specific status of two Macrolophus populations collected on their respective host plants (Dittrichia viscosa and tomato) through crossing experiments. Then, using multivariate morphometric analysis, we proposed a linear discriminant function that combines head measurements separating males from the two species without error. Finally, we designed specific primers for a mitochondrial DNA region that were able to distinguish field-collected Macrolophus individuals through conventional PCR. In conclusion, the tools developed in the present study will allow reliable identification of the Macrolophus species present in crops and in the native flora that are the source of populations that colonise them. They will also allow correct identification of mass reared Macrolophus to be introduced in greenhouse crops in inoculative releases. [ABSTRACT FROM PUBLISHER]

Bacillus thuringiensis Berliner toxins are highly specific in terms of insect pest targeted. For example, Cry3Bb is active against Coleoptera. As a consequence, in the framework of using genetically modified plants expressing different Bt toxins in sustainable agriculture, there is a growing interest about the impact of these crops on the environment and on non-target organisms. The effects of genetically modified Bt-tomato plants expressing the toxin Cry3Bb on the aphid Macrosiphum euphorbiae (Thomas) and its natural enemies, the generalist predator Macrolophus caliginosus Wagner and the endoparasitoid wasp Aphidius ervi Haliday, were assessed under laboratory conditions. No significant differences between performance of M. euphorbiae were observed on genetically modified tomato plants (line UC82Bt) with respect to their near-isogenic control line (line UC82). Immunoassays did not detect Cry3Bb protein in M. euphorbiae developing on Bt-expressing tomato plants. Similarly, no significant differences were found on the longevity and prey consumption of M. caliginosus when fed aphids reared on UC82Bt or on UC82. Moreover, the genetic modification did not affect the attractiveness of uninfested tomato plants toward A. ervi. It is therefore concluded that Cry3Bb-expressing tomato plants did not show any acute adverse effects on the biological parameters of the non-target herbivore M. euphorbiae or its natural enemies, M. caliginosus and A. ervi, under laboratory conditions. [ABSTRACT FROM PUBLISHER]

Abstract: The effect of the combined use of Encarsia formosa or Macrolophus caliginosus and one of three marketed mycoinsecticides, Mycotal® (Leucanicillium muscarium-based), Naturalis-L™ (Beauveria bassiana-based) and PreFeRal® (Isaria fumosorosea-based), on the control of the whitefly, Trialeurodes vaporariorum, was studied under laboratory and greenhouse conditions. The results of both types of tests, the bioassays and the greenhouse trials, for all combinations of E. Formosa with each of the three mycoinsecticides showed that the total mortality of larval populations of T. vaporariorum was not affected. The mortality of T. vaporariorum larvae treated in the second instar revealed the capacity for both B. bassiana- and L. muscarium-based formulations and E. formosa to kill the host either separately or in association. Because of its higher pathogenic activity (under our test conditions), L. muscarium provoked a large proportion of mycoses in larvae exposed to parasitization. In contrast, the efficacy of parasitization was higher in larvae treated with B. bassiana and exposed to E. formosa because of a lower pathogenic activity of the fungus. Bioassays carried out with third-instar larvae of T. vaporariorum showed a low susceptibility to both tested fungi. Consequently, mortalities recorded in larvae subjected to the combined treatments by consecutive exposures or at 2–4days post-parasitization were mainly caused by the development of the parasitoid. Greenhouse trials showed that fungus-induced mortality of T. vaporariorum in plants treated with L. muscarium, I. fumosorosea, and B. Bassiana was significant compare to control. L. muscarium, B. bassiana and I. fumosorosea killed young whitefly larvae and limited parasitization to 10% or less. Second-instar larvae of M. caliginosus were not susceptible to L. muscarium and B. bassiana formulations with any mode of contamination: direct spraying of larvae, spraying on the foliar substrate or by contaminated T. vaporariorum prey. In greenhouse trials, M. caliginosus populations treated with fungi were not significantly affected compared to controls. [Copyright &y& Elsevier]

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a global pest on numerous crops, including vegetables. Weekly inundative releases of a coccinellid predator ( Coccinella undecimpunctata L. [Coleoptera: Coccinellidae]), a common green lacewing predator ( Chrysoperla carnea Stephen [Neuroptera: Chrysopidae]), and a mirid predator ( Macrolophus caliginosus[Wagner][Hemiptera: Miridae]) were independently made in three vegetable crops (cabbage [ Brassica oleracea var. capitata L.], cucumber [ Cucumis sativus L.], and squash [ Cucurbita pepo L.]) for the management of the sweetpotato whitefly. Approximately 1 million to 2.5 million larvae or nymphs of each predator were released in the vegetable crops during 20 weeks. Whitefly populations were reduced by ≈ 25%-45% during most of the season in each crop where each predator was released. The effect of each predator was similar on whitefly population reduction. Late in the season (October) when whitefly populations were low, generally no benefit was obtained from releasing the predators. Numbers of predators recovered during sampling in all crops were greatest for C. carnea, but this corresponded with the fact that more individuals of this predator were released than any other predator in the experiment. These results help define the utility of these natural enemies for managing B. tabaci in vegetable crops. [ABSTRACT FROM AUTHOR]

The zoophytophagous mirid bug Macrolophus caliginosus is an important biocontrol agent of whiteflies in the Mediterranean region. Periods of low productivity in commercial breeding units and unsuccessful establishment in greenhouses prompted this study of mating behaviour. Here we describe copulation behaviour, the diel mating periodicity and post-copulatory refractory period. A natural plant substrate needs to be provided if one wants to observe the copulatory behaviour of M. caliginosus in the laboratory. There was no apparent directional orientation in the approach of the two sexes, instead males pursued females after "accidentally" contacting them. Males mounted females from above, very rapidly, and without any obvious courtship behaviour, and copulation duration was very consistent (286.33 ± 4.23 s, mean ± SE). Observations over a 24-h period showed that mating was most frequent in the 8-h scotophase and first half of the 16-h photophase than in the second half of the photophase. Mated females became strongly unreceptive to new male mounting attempts, shaking their abdomen and leaving the plant if harassed. To determine the duration of the post-mating refractory period mating receptivity of females that had mated 1 or 2 weeks earlier was compared with that of virgin females of similar age. Mated females remained unreceptive even 2 weeks after mating, whereas half of the virgin females of equivalent age mated. Mated females were more likely to abandon a plant than virgin females when harassed by a male. Most males remated a few minutes after mating for the first time. M. caliginosus is atypical among mirids in that females apparently mate only once. [ABSTRACT FROM AUTHOR]

Sustainability in Mediterranean greenhouse agrosystems involves environmentally-friendly techniques based on biological and non-chemical methods. Deleafing is a common agricultural practice used to accelerate fruit ripening and facilitate farming methods. However, deleafing may have an impact on mirids, a natural predator used to control whiteflies, which are considered among the most noxious insect pests of field and greenhouse crops worldwide. Here we studied the impact of leaf removal on populations of mirids. Two deleafing practices were tested: (a) regular deleafing, with the first removal of 2 leaves per plant 10 weeks after sowing; and (b) delayed deleafing, in which the first removal was delayed by 14 days. Our results show that regular deleafing had a strong negative impact on mirid populations. Indeed, the first deleafing of the regular method eliminated 74% of young nymphs. Such a loss was not observed with the delayed method because nymphs were older and already distributed on leaves which were never thinned. As a consequence of this initial difference, mirid populations were 60% higher in the delayed than in the regular deleafing treatments at the end of the crop. The biological control of whiteflies was less efficient in the regular deleafing crop for which densities were, on average, 30% higher than in the delayed deleafing crop. Such inefficiency could call into question the sustainability in protected tomato crops of environmentally-friendly techniques focused on reducing the pesticides used. [ABSTRACT FROM AUTHOR]

Plants infested with a single herbivore species can attract natural enemies through the emission of herbivore-induced plant volatiles (HIPVs). However, under natural conditions plants are often attacked by more than one herbivore species. We investigated the olfactory response of a generalist predators Macrolophus caliginosus to pepper infested with two-spotted spider mites, Tetranychus urticae, or green peach aphid, Myzus persicae, vs. plants infested with both herbivore species in a Y-tube olfactometer set up. In addition, the constituents of volatile blends from plants exposed to multiple or single herbivory were identified by gas chromatography-mass spectrometry (GC-MS). The mirid bugs showed a stronger response to volatiles emitted from plants simultaneously infested with spider mites and aphids than to those emitted from plants infested by just one herbivore, irrespective of the species. Combined with results from previous studies under similar conditions we infer that this was a reaction to herbivore induced plant volatiles. The GC-MS analysis showed that single herbivory induced the release of 22 additional compounds as compared with the volatiles emitted from clean plants. Quantitative analyses revealed that the amount of volatile blends emitted from pepper infested by both herbivores was significantly higher than that from pepper infested by a single herbivore. Moreover, two unique substances were tentatively identified (with a probability of 94% and 91%, respectively) in volatiles emitted by multiple herbivory damaged plants: α-zingiberene and dodecyl acetate. [ABSTRACT FROM AUTHOR]

Abstract: The mirid bug Macrolophus caliginosus is commercially reared on eggs of Ephestia kuehniella, constituting an effective but expensive factitious food. Artificial diets can decrease the rearing costs of this natural enemy, but developing and evaluating an artificial diet is a very time-consuming activity. In the current study, development and reproduction of M. caliginosus on two artificial diets based on egg yolk were investigated. The artificial diets resulted in longer development and lower adult weights, but survival was comparable with that of control insects fed E. kuehniella eggs. Reproductive potential of the predator reared on factitious and artificial foods was assessed using a dissection method. The influence of nymphal food on fecundity was less important than that of adult food. Adults fed E. kuehniella eggs had a preoviposition period of about 4 days, whereas adults offered only plant material started laying eggs about 7 days after emergence. Ovarian scores at day 7 were higher for females fed E. kuehniella eggs than for those given access only to a tobacco leaf. Ovarian scores were not significantly affected by mating status. In a final test, a parallel comparison of two methods for assessing reproductive response to diet was made. Here, adult couples were offered one of four diets: E. kuehniella eggs, one of two artificial diets or no food. Half of the females were dissected and the other half was held for determining lifetime oviposition. Females fed E. kuehniella eggs had superior ovarian scores and laid more eggs than those fed either artificial diet or those given no extra food. A good correlation (r =0.97) was obtained between ovarian scores and oviposition data, indicating that dissecting females after 1 week provides a reliable estimate of fecundity as affected by diet quality. Rapid reproductive assessments as used in the current study will help to increase the rate of development of artificial diets and may contribute to more cost effective production methods for augmentative biological control agents. [Copyright &y& Elsevier]

It has been shown that many natural enemies of herbivorous arthropods use herbivore induced plant volatiles (HIPVs) to locate their prey. Herbivores can also exploit cues emitted by plants infested with heterospecifics or conspecifics. A study was conducted to test whether green bean HIPVs as well as odours emitted directly by spider mites influenced the orientation behaviour of the predatory mirid bug, Macrolophus caliginosus and its prey, Tetranychus urticae in a Y-tube olfactometer. Our results show that both spider mites and M. caliginosus preferred spider mite infested green bean plants to uninfested plants. For M. caliginosus this response was mediated by HIPVs whereas for T. urticae it was mediated through a composite response to both HIPVs and odours emitted directly by the conspecifics (and their associated products). The results may be of use in practical biocontrol situations, through e.g., plant breeding for improved HIPV production, conditioning of mass-reared predators to appropriate cues, and employment of ‘push-pull-strategies’ by using HIPVs. [ABSTRACT FROM AUTHOR]

A study predation choices of Macrolophus caliginosus Wagner (Heteroptera Miridae) late instars and adults, when offered various developmental stages (eggs and nymphs) of the recently established whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), was made based on two preference indices. In addition, prey choices of late instars when presented with three ratios of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) and B. tabaci at a similar developmental stage (eggs, young or late instars) were assessed. M. caliginosus preferred older nymphs of B. tabac, than any other stage. It also chose T. vaporariorism over B. tabaci, unless the latter consisted of >75% of the available prey. These results suggested that M. caliginosus might interfere with parasitoids such as Encarsia, Eretmocerus, or Amitus spp. because all three species emerge from the host pupal case. Furthermore, in mixed infestations, M. caliginosus preference for T. vaporariorum might either negatively affect the control of B. tabaci, or, contrarily, enhance the predator population, before a B. tabaci outbreak occurs in the greenhouse. [ABSTRACT FROM AUTHOR]

Abstract: This work presents the results of an investigation that aimed to evaluate the effectiveness of releases of the omnivorous predator Macrolophus caliginosus Wagner (Heteroptera, Miridae) in the control of Bemisia tabaci Gennadius (Homoptera, Aleyrodidae) on greenhouse melon. Two greenhouse trials were performed, one in spring and one in summer. Adults of M. caliginosus were released at two release rates (two and six per plant) in an initial infestation of 10 adult whitefly per plant. The high release rate did control the whitefly populations. Results of the lower release ratio did not work in the second trial, presumably due to excessive pruning of the crop that may have affected predator establishment. No damaged fruits were recorded. Laboratory trials were also done to examine the effects of plant and variable prey availability on predator fertility and survivorship. Results showed that low-prey availability significantly reduced survivorship and fertility of M. caliginosus, and explained why predator establishment was the same for both predator release rates. [Copyright &y& Elsevier]

Abstract: A meat-based diet was tested for the rearing of the polyphagous predatory bug Macrolophus caliginosus (Heteroptera: Miridae). Several continuous generations were completed with this meat diet, without the availability of any plant material and using dental cotton rolls as an oviposition substrate. When meat-reared insects were compared with conventionally reared individuals (on tobacco plants and with moth eggs as prey) they were significantly smaller in size, lighter in weight, and displayed delayed development. When potato sprouts were tested as oviposition substrate, consistent improvement was observed in oviposition and other life history traits. Performance of adults from the seventh meat-diet generation was evaluated on three preys: the greenhouse whitefly, Trialeurodes vaporariorum; the sweet potato whitefly, Bemisia tabaci; and the two-spotted spider mite, Tetranychus urticae. Predation efficiency for meat-diet females and nymphs was similar to that of conventionally reared insects. The rearing method proposed in this work constitutes an alternative to the conventional method and represents an improvement in the production of this predator. [Copyright &y& Elsevier]

Colonization of tomato greenhouses by native predatory mirid bugs at the end of the spring cycle is common in the western Mediterranean area when no broad-spectrum insecticides are applied. Due to their polyphagy, these predators interact with pest populations and also with other natural enemies present in the crop. In this work we evaluate the abundance and timing of greenhouse colonization by these predators and their interaction with the greenhouse whitefly Trialeurodes vaporariorum, a key crop pest, and its introduced parasitoid Encarsia formosa. Although quite unpredictable, natural colonization of greenhouses by Macrolophus caliginosus and Dicyphus tamaninii, the two predominant species in our location, usually leads to the establishment of predator populations in the crop that subsequently prey on greenhouse whitefly. No preference for parasitized pupae was observed in greenhouse samples, while laboratory experiments revealed a marked tendency to avoid parasitoid pupae. In our area, IPM programs for greenhouse tomatoes and other vegetables should take advantage of the presence of this predator complex by allowing the immigration and establishment of its populations without disturbing them with highly toxic and non-selective insecticides. [Copyright &y& Elsevier]

While measuring the predators'' functional response for the assessment of their aptitude as biological control agents, the time that predators allocate to activities other than handling or searching for the prey, the preference to allocate some of these activities to different locations, and the patch departure tendencies dependent on prey density, are ignored. We test whether these factors have an effect on the predation rates of three plant-inhabiting predators that are used as biological control agents, Dicyphus tamaninii Wagner, Macrolophus caliginosus Wagner, and Orius majusculus (Reuter), at high and low densities of pupae of Trialeurodes vaporariorum Westwood. Continuous behavioral observations of the three species were done on a non-enclosed plant, thus allowing predators to visit different plant locations and to leave the plant at their will. We compared the current results with the ones obtained in a previous functional response experiment. We found that predators'' plant-departure tendency at low prey density was the main reason for differences found in attack rates between experiments. The predators'' preference for laying eggs in the stem, thus spending time in prey-free areas, explained the differences found in attack rates at high prey density. Our results provide more realistic information on predators'' performance to better assess their suitability as biological control agents. Predator behavioral differences depending on prey densities allow for a complementary use of these predators for biological control. [Copyright &y& Elsevier]

Biological control provides an environmentally harmonious and potentially stable management tactic to combat noxious pests such as Bemisia tabaci, notorious for its resistance to synthetic pesticides. Bioassays conducted under control chamber conditions integrating applications of the parasitoid Encarsia formosa, reared for 20 years on Trialeurodes vaporariorum, and the fungus Verticillium lecanii on the third-fourth instar nymphs of B. tabaci on tomato, showed a comparable effect between the parasitoid-fungus combined treatment and the fungus treatment alone (70.7% vs. 70.4%). Analysis of our results indicates antagonism between the two biocontrol agents related to the parasitoids’ ability to discriminate between infected and healthy B. tabaci nymphs. The parasitoid treatment alone produced 36.3% mortality, with no mortality in the distilled water controls. The behavioural performance of the parasitoid could have either genetic or environmental causes. Bioassays studying the feeding habit of the imported mirid predator Macrolophus caliginosus (adults) and the indigenous mirid Camptotylus reuteri (nymphs and adults) on eggs, or early second instar nymphs of B. tabaci, and choice preference tests indicated a significant difference in feeding between M. caliginosus and C. reuteri. There was no significant difference in percentage feeding of M. caliginosus on eggs (2.2%) or second instar nymphs (8.0%). There was a significant difference in feeding of M. caliginosus adults (18.6%) when offered eggs and second instars in the same arena compared with eggs or second instars offered separately. These results could be attributed to the biological behaviour of the predator having a type III functional response. Studies with the local C. reuteri species showed no significant difference in adult and nymphal consumption on second instars of B. tabaci compared with nymphs on eggs. However, C. reuteri adults fed less on eggs compared with nymphs. This local predatory species appears to be more efficient than M. caliginosus in feeding on particular stages of B. tabaci without depending on prey density. This is further supported by the low consumption of both adults and nymphs in the choice test (4% and 2.3%, respectively) compared with M. caliginosus adults (18.6%). [ABSTRACT FROM AUTHOR]

The mutual predation between two polyphagous predators, Orius majusculus (Reuter) (Hemiptera, Anthocoridae) and Macrolophus caliginosus Wagner (Heteroptera: Miridae), was examined in laboratory experiments with and without presence of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Adults of O. majusculus preyed upon M. caliginosus in the absence and in some circumstances also in the presence of F. occidentalis , whereas neither nymphs nor adults of M. caliginosus preyed upon O. majusculus. Orius majusculus nymphs did not prey upon M. caliginosus . The predation of O. majusculus on F. occidentalis was unaffected by the presence of M. caliginosus suggesting that the presence of this mirid will not hamper biological control of F. occidentalis. [ABSTRACT FROM AUTHOR]

In northeast Spain, the most common predators found in tomato fields and greenhouses are the mirids Macrolophus caliginosus Wagner and Dicyphus tamaninii Wagner. Natural colonization occurs during the growing season and both species prey on whiteflies. Because D. tamaninii can damage tomato fruits during periods of prey scarcity, a semifield experiment was carried out to evaluate whether the presence of M. caliginosus affects damage produced by D. tamaninii. In a tomato greenhouse, 60 plants were individually caged and distinct predator treatments were introduced: D. tamaninii, D. tamaninii + eggs of Ephestia kuehniella Zeller, D. tamaninii + M. caliginosus, M. caliginosus alone, and a control without any insect. Damage to tomato fruits was recorded (>25% of the fruit) in all the treatments with D. tamaninii, whereas no significant damage was detected with M. caliginosus alone. Finally, no intraguild predation was detected between both mirid species. [ABSTRACT FROM PUBLISHER]

Macrolophus caliginosus (Wagner) is currently commercialized in Europe for the control of whiteflies in tomato greenhouses. Another mirid predator, Dicyphus tamaninii Wagner, spontaneously colonizes Mediterranean greenhouses. The impact of the presence of D. tamaninii on predation of the greenhouse whitefly (Trialeurodes vaporariorum Westwood) by M. caliginosus was investigated in the laboratory on tomato plants during four days. No significant interspecific competition was recorded between mirid nymphs and no significant intraguild predation was observed. Higher level of predation of the whitefly populations was achieved by D. tamaninii alone, than by M. caliginosus alone. Predation by the heterospecific combination (M. caliginosus + D. tamaninii) was similar to the results obtained by conspecific treatments. No intraspecific competition was recorded with D. tamaninii, nor with M. caliginosus. Finally, the distribution of whitefly predation on the plant by the mirids changed according to the predator treatment. The heterospecific combination of both mirids had a higher predation rate on lower leaves of the plant than monospecific combinations. Overall, the presence of D. tamaninii did not disrupt whitefly predation by M. caliginosus and could even increase the level of predation. [Copyright &y& Elsevier]

Abstract This study investigated the effect of temperature on the development and winter survival of the predatory mirid Macrolophus caliginosus Wagner, recently introduced into the U.K. as a biocontrol agent for glasshouse whitefly Trialeurodes vaporariorum . The developmental threshold for M. caliginosus calculated by three methods was between 7.3 and 8.4 °C, with a day-degree requirement per generation varying between 472 and 524 day-degrees. It was estimated that under outdoor conditions M. caliginosus could complete two generations per year in the U.K. All life stages of M. caliginosus had supercooling points around -20 °C, with some pre-freeze mortality evident in both acute and chronic low temperature exposures. Acclimation increased survival of nymphal M. caliginosus from approximately 24–52 days when exposed to a constant 0 °C. Provision of prey extended survival of nymphs in the laboratory at a constant 5 °C from 39 to 64 days and in the field by c . 150 days. The results are discussed in the context of the occurrence and establishment of M. caliginosus in the U.K. and the need to develop a reliable risk assessment system for non-native species used in glasshouse biocontrol. [ABSTRACT FROM AUTHOR]

Dicyphus tamaninii and Macrolophus caliginosus are predatory bugs that significantly contribute to control of pests in tomato crops following early colonisation in spring from winter refuges. This paper aimed to determine the influence of the richness of nearby potential predator sources at the time of arrival, amount and establishment of the mirid bugs in tomato fields. For this, six tomato fields were selected that showed a gradient of vegetational settings in the landscape. Crops and non-crop vegetation were sampled with a vacuum suction sampler and abundance of potential colonising predators was estimated. Soon after transplantation of tomatoes, weekly visual counts on the crop were initiated and continued for 8 weeks to estimate densities of Trialeurodes vaporariorum adults, the most abundant pest, and predator adults and nymphs. Time of predator arrival in each field, which varied between 6 and 8 weeks after seedling transplantation, was not related to the respective predator abundance in the surrounding vegetation. Eleven weeks after transplantation, fields differed in their cumulative numbers of insect-days (greenhouse whitefly, predator adults and nymphs). Differences in predator-days were not related to densities of greenhouse whitefly-days but to predator abundance in field surroundings. Fields were also colonised by predators coming from distant sources. Mirid bugs were more abundant in outer rows, particularly in fields with close predator sources and were concentrated on plants with higher whitefly densities. Predator nymphs were detected soon after adult arrival and distributed in the field mostly according to adult predator or prey spatial pattern. Presence of winter refuges for predators in nearby habitats increases the amount of colonisation. However, in order to rely on predator colonisation into fields, the stimuli involved in the predator movement from winter refuges to crops and the predator dispersal capacity should be further investigated. [Copyright &y& Elsevier]