Predator Macrolophus Pygmaeus Research Articles

Effects of far-red light on the behaviour and reproduction of the zoophytophagous predator Macrolophus pygmaeus and its interaction with a whitefly herbivore.

Plants can detect neighbouring plants through a reduction in the ratio between red and far-red light (R:FR). This provides a signal of plant-plant competition and induces rapid plant growth while inhibiting defence against biotic stress, two interlinked responses designated as the shade avoidance syndrome (SAS). Consequently, the SAS can influence plant-herbivore interactions that could cascade to higher trophic levels. However, little is known about how the expression of the SAS can influence tritrophic interactions. We investigated whether changes in R:FR affect the emission of herbivore-induced plant volatiles (HIPVs), and whether these changes influence the attraction of the zoophytophagous predator Macrolophus pygmaeus. We also studied how the expression of the SAS and subsequent inhibition of plant defences affects the reproduction of M. pygmaeus in both the presence and absence of the greenhouse whitefly (WF) (Trialeurodes vaporariorum) as arthropod prey. The results show that changes in R:FR have little effect on HIPV emissions and predator attraction. However, a reduction in R:FR leads to increased reproduction of both the predator and the WFs. We discuss that shade avoidance responses can increase the population development of M. pygmaeus through a combination of reduced plant defences and increased herbivore densities.

The omnivorous predator Macrolophus pygmaeus induces production of plant volatiles that attract a specialist predator

It has become clear that omnivorous predators can induce plant defences that affect the performance and host plant choice of herbivores. They are also known to induce the production of plant volatiles that can affect the behaviour of herbivores searching for plants. These volatiles may also affect the searching behaviour of other predators, which was investigated here. The predatory mite Phytoseiulus persimilis preferred plants previously exposed to the omnivorous mirid Macrolophus pygmaeus over clean plants. The mites were equally attracted to plants previously exposed to the omnivore and subsequently infested by spider mites (Tetranychus urticae, prey of the predatory mite and the omnivore) and plants infested with spider mites alone. Moreover, the mites were more attracted to plants infested with prey and subsequently exposed to the omnivore than plants infested with prey but not exposed to the omnivore. The predatory mites were also significantly more attracted to plants on which the omnivores were still present. Experience of the predatory mites with volatiles from plants previously exposed to the omnivore and without prey resulted in a loss of the preference for volatiles emitted by plants exposed to the omnivore. Analysis of the volatiles showed that plant exposure to omnivores induced qualitative and quantitative changes in the volatile blend. Together, these results suggest that omnivorous predators induce the production of plant volatiles that can interfere with the searching behaviour of other predators. The consequences of such interference for biological pest control remain to be investigated.

Banker plants and landscape composition influence colonisation precocity of tomato greenhouses by mirid predators

Conservation biological control involves manipulation of the environment to enhance the effectiveness of natural enemies in controlling crop pests. In this study, we combined historical data, sticky trap sampling of tomato greenhouses and beat sampling of adjacent vegetation to identify which greenhouse characteristics, habitat management practices and landscape features favour an early colonisation of tomato greenhouses by the key mirid predator Macrolophus pygmaeus and its establishment in NE Spain. Results show that landscape composition and the use of Calendula officinalis banker plants inside the greenhouse are key factors. In general, greater amounts of herbaceous semi-natural cover at the landscape scale promoted M. pygmaeus colonisation, while the use of C. officinalis banker plants encouraged M. pygmaeus colonisation independently of the landscape context. We identified host plants adjacent to tomato greenhouses that sustain M. pygmaeus populations; however, they did not have a major effect on M. pygmaeus colonisation compared to larger landscape and banker plant effects. Early colonisation of greenhouses by this predator species also translated into lower accumulated incidence of pests at the end of the sampling period. This study demonstrates the importance of active habitat management practices in promoting the early arrival of M. pygmaeus in greenhouses with delayed spontaneous colonisation.

Predator size affects the intensity of mutual interference in a predatory mirid.

Interference competition occurs when access to an available resource is negatively affected by interactions with other individuals, where mutual interference involves individuals of the same species. The interactive phenomena among individuals may be size‐dependent, since body size is a major factor that may alter prey consumption rates and ultimately the dynamics and structure of food webs.A study was initiated in order to evaluate the effect of mutual interference in the prey‐specific attack rates and handling times of same size class predators, incorporating variation in consumer size. For this purpose, laboratory functional response experiments were conducted using same age predators, that is, newly hatched (first instar) or mature (fifth instar) nymphs of the polyphagous mirid predator Macrolophus pygmaeus preying on Ephestia kuehniella (Lepidoptera: Pyralidae) eggs.The experiments involved four predator density treatments, that is, one, two, three, or four predators of same age, that is, either first‐ or fifth‐instar nymphs, which were exposed to several prey densities. The Crowley–Martin model, which allows for interference competition between foraging predators, was used to fit the data.The results showed that mutual interference between predator's nymphs may occur that affect their foraging efficiency. The values of the attack rate coefficient were dependent on the predator density and for the first‐instar nymphs were significantly lower at the highest predator density than the lower predator densities, whereas for the fifth‐instar nymphs in all density treatments were significantly lower to that of the individual foragers' ones.These results indicate that mutual interference is more intense for larger predators and is more obvious at low prey densities where the competition level is higher. The wider use of predator‐dependent functional response models will help toward a mechanistic understanding of intraspecific interactions and its consequences on the stability and structure of food webs.

Does the plant defense priming compound β-aminobutyric acid affect the performance of Macrolophus pygmaeus when used to control Bemisia tabaci in tomato?

The β-aminobutyric acid (BABA) is a plant defense priming compound highly effective in controlling important tomato diseases and plant-parasitic nematodes. It has also been shown to induce resistance against phytophagous insects such as aphids. This study examines the effect of BABA on the performance of the tomato pest Bemisia tabaci (MEAM 1, previously known as Biotype B) and its zoophytophagous predator Macrolophus pygmaeus under laboratory and greenhouse conditions. Tomato plants were treated with BABA 25 mM applied by soil drenching. The effect of BABA on the fertility and juvenile development of two generations of B. tabaci and M. pygmaeus was evaluated. Our results showed no effect of BABA on the juvenile development or adult fecundity/fertility of both the whitefly and its predator. The non-interference of BABA with M. pygmaeus and B. tabaci assures that the control of the whitefly with this mirid bug will not be affected when this elicitor is applied to the crop. Further studies are needed to clarify the mechanisms underlying BABA-plant-whitefly-predatory myrids interactions.

Combined thermal and insecticidal stresses on the generalist predator Macrolophus pygmaeus

Ecotoxicological risk assessments of pesticides on non-target arthropods are often carried out under constant and optimal temperature regimes. However, living organisms rarely experience these conditions in real field situations. Understanding the impact of pesticides on non-target beneficial arthropods under temperature stresses is especially important in terms of global warming. We assessed the lethal and sublethal effects of four modern insecticides (chlorantraniliprole, cyantraniliprole, spinetoram, spinosad), on the generalist predator Macrolophus pygmaeus (Hemiptera: Miridae) under a range of temperatures (from 10 to 40°C) frequently experienced in a real field scenario. A reduction coefficient (Ex) was calculated by summarizing the mortality and predator reproductive capacity and, the chemicals were classified according to the International Organization for Biological Control (IOBC) toxicity classes. The insecticides showed a marked synergistic effect with temperature, as the predator mortality and reproductive outputs were significantly correlated with increasing temperatures. Spinosyns interacted significantly with temperature causing the highest mortality and lowest fertility rates. Anthranilic diamides showed a safer ecotoxicological profile compared to spinosyns, with cyantraniliprole being more harmful than chlorantraniliprole. These results suggest that temperature should be taken into account in pesticide ecotoxicology studies within the framework of integrated pest management and the recent climate changes.

Macrolophus pygmaeus (Hemiptera: Miridae) foraging on tomato leaves from different plant strata

This study investigates the foraging activity of the generalist predator Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) on tomato leaves of different vertical plant strata (apex, top, middle and lower). On a leaflet of each tested leaf, ten 2nd instar nymphs of the aphid Myzus persicae were established with the aid of harmless glue, as prey. It was observed that prey consumption was highest on the lower leaves. There was no significant difference in prey consumption between middle and top leaves but it significantly reduced on the apex leaves as compared to the top and the lower leaves. Behavioural observations were conducted to assess the time budgets (i.e. time spent in each activity such as searching, resting, grooming) of the foraging predator on leaves of each plant strata. The predator spent significantly more time in grooming on apex than on lower leaves whereas it showed a higher tendency to fall off from the apex leaves than the leaves of the other plant strata. The apex leaves had the highest trichome density and this may impede movement of the predator. In the third experiment, the prey consumption of M. pygmaeus nymphs was reduced with the increase of distance between its release point and the prey patch on a tomato plant. In conclusion, M. pygmaeus nymphs are most efficient in foraging on the middle or lower leaves of young tomato plants whereas their prey searching efficiency is influenced by the distance between their release point and the prey patch. Therefore, the efficacy of M. pygmaeus nymphs in pest control may be benefited if released close to prey patches but not on the apex leaves.

Tomato Inoculation With a Non-pathogenic Strain of Fusarium oxysporum Enhances Pest Control by Changing the Feeding Preference of an Omnivorous Predator

Mirid predators, a special group of plant-feeding omnivorous predators, have become important biological control agents for pest control in greenhouse cropping systems. Their efficacy and behavior may potentially be affected by microorganisms that induce plant defenses or change plant quality. Here we studied the interaction between a root restricted endophytic non-pathogenic strain of Fusarium oxysporum (Fo162) in tomato plants, the greenhouse whitefly Trialeurodes vaporariorum (Westwood) and the plant-feeding mirid predator Macrolophus pygmaeus (Rambur). In the absence of prey, inoculation of tomato plants with the Fo162 endophyte significantly reduced the reproduction of M. pygmaeus compared to plants without the endophyte. In contrast, the population growth of M. pygmaeus was not affected by the Fo162 endophyte in the presence of whiteflies. Moreover, the combination of the predator and endophyte resulted in lower whitefly densities than the predator alone. Whitefly population development was not different between endophyte-inoculated and untreated plants. Thus, endophyte inoculation of tomato plants seems to shift the feeding preference of this omnivorous predator from plant consumption towards relatively more prey consumption, resulting in enhanced suppression of the herbivore. Moreover, the negative effect of the endophyte on M. pygmaeus reproduction could easily be eliminated by providing decapsulated cysts of Artemia franciscana Kellogg as a supplemental food source. Together, this suggests an overall net positive effect of the Fo162 endophyte on a preventive biological control strategy in tomato using M. pygmaeus. Besides the enhanced whitefly control, endophyte-inoculation of tomato plants both with or without the predator also resulted in a higher yield and a reduced number of fruits with blossom-end rot, a disorder caused by limitations in uptake and transport of calcium to the fruits. This suggests that the Fo162 endophyte is also involved in the acquisition of essential nutrients for the benefit for the plant. Since both the Fo162 endophyte and the predator M. pygmaeus can induce plant defense, further studies need to elucidate the exact mechanisms that occur when both organisms are present. Our findings confirm the importance of studying endophytes and induced plant responses in a multi-trophic context with herbivores and their natural enemies.

Plant feeding by an omnivorous predator affects plant phenology and omnivore performance

Plant feeding by omnivorous predators can induce plant defences, which decreases the performance of herbivores and influence behaviour of other predators. However, it is not known what are the consequences of this feeding for the plant and how this, in turn, affects the omnivore. We therefore investigated the effects of plant feeding by the omnivorous predator Macrolophus pygmaeus on plant development and reproduction. We also assessed the effects of these plant changes on survival and reproduction of the omnivore. Sweet pepper plants exposed to M. pygmaeus had significantly lower numbers of leaves and open flowers than clean plants, but numbers of fruits were similar. Moreover, the presence of the omnivore significantly shortened the period for flowers to become fruits. The dry weights of leaves plus stems and fruits were similar on clean plants and plants with the omnivore. Significantly higher numbers of seeds were found in fruits from plants with the omnivore than from clean plants. The survival rates of M. pygmaeus females and nymphs increased with numbers of flowers. Our results show that the presence of this omnivorous predator can benefit plants by increasing seed production, but the changes in plant phenology do not seem to benefit the omnivore.

The omnivorous predator Macrolophus pygmaeus, a good candidate for the control of both greenhouse whitefly and poinsettia thrips on gerbera plants.

The poinsettia thrips Echinothrips americanus Morgan is a relatively new pest that has spread rapidly worldwide and causes serious damage in both vegetable and ornamental plants. In this study, we investigated if and how effective this pest can be controlled in gerbera by the omnivorous predator Macrolophus pygmaeus (Rambur). Because herbivores on plants can interact through a shared predator, we also investigated how poinsettia thrips control is affected by the presence of the greenhouse whitefly Trialeurodes vaporariorum (Westwood), a pest that commonly coexists with E. americanus in gerbera. In laboratory studies, we found that the predator M. pygmaeus fed on both pests when offered together. Olfactometer tests showed a clear preference of the predators for plants infested by whiteflies but not by thrips. In a greenhouse experiment, densities of both pests on single gerbera plants were reduced to very low levels by the predator, either with both pests present together or alone. Hence, predator‐mediated effects between whiteflies and thrips played only a minor role. The plant feeding of the shared predator probably reduced the dependence of predator survival and reproduction on the densities of the two pests, thereby weakening potential predator‐mediated effects. Thus, M. pygmaeus is a good candidate for biological control of both pests in gerbera. However, further research is needed to investigate pest control at larger scales, when the pests can occur on different plants.

Herbivores avoid host plants previously exposed to their omnivorous predator Macrolophus pygmaeus

Herbivorous arthropods use various cues to choose suitable host plants. We investigated whether three species of herbivores use cues associated with their omnivorous predator Macrolophus pygmaeus to select host plants. Earlier, we found that this omnivore induces plant defences which decreased the performance of two of the herbivores, i.e. the spider mite Tetranychus urticae and the western flower thrips Frankliniella occidentalis, whereas the green peach aphid Myzus persicae was not affected. Hence, the spider mite and thrips were expected to avoid plants that were previously exposed to M. pygmaeus because of their lower quality, and the aphid was not expected to avoid exposed plants because they were of equal quality as unexposed plants. However, the cues left behind by M. pygmaeus may also be indicative of predation risk, in which case all three herbivores were expected to avoid exposed plants. Spider mites and western flower thrips preferred clean plants over plants that had previously been exposed to M. pygmaeus, but no longer harboured this omnivore. Aphids showed no preference, in agreement with their performance, but not in agreement with reducing predation risk. We furthermore showed that the preference of spider mites and thrips for clean plants increased through time. Higher proportions of aphids left plants previously exposed to M. pygmaeus than clean plants through time. Hence, omnivorous predators can decrease herbivore densities on plants not only by killing them but also by indirectly affecting herbivore host plant selection.

Phytophagy of omnivorous predator Macrolophus pygmaeus affects performance of herbivores through induced plant defences

Plants possess various inducible defences that result in synthesis of specialized metabolites in response to herbivory, which can interfere with the performance of herbivores of the same and other species. Much less is known of the effects of plant feeding by omnivores. We found that previous feeding of the omnivorous predator Macrolophus pygmaeus on sweet pepper plants significantly reduced reproduction of the two-spotted spider mite Tetranychus urticae and western flower thrips Frankliniella occidentalis on the same plants, also on leaves that had not been exposed to the omnivore. In contrast, no effect was found on the reproduction of the green peach aphid Myzus persicae. Juvenile survival and developmental time of T. urticae and M. persicae, and larval survival of F. occidentalis were not affected by plant feeding by M. pygmaeus. Larvae of F. occidentalis feeding on leaves previously exposed to M. pygmaeus required longer to develop into adults. Defence-related plant hormones were produced locally and systemically after exposure to M. pygmaeus. The concentrations of 12-oxo-phytodienoic acid and jasmonic acid–isoleucine in the attacked leaves were significantly higher than in the corresponding leaves on the uninfested plants, and jasmonic acid concentrations showed the same trend, suggesting that jasmonic-acid-related defence pathways were activated. In contrast, similar concentrations of salicylic acid were found in the attacked leaves of M. pygmaeus-infested plants and uninfested plants. Our results show that plant feeding by omnivorous predators decreases the performance of herbivores, suggesting that it induces plant defences.

Description of the Egg and Nymphal Instars of Mαcrolophus pygmαeus Rambur (Hemiptera: Miridae)

The egg and the nymphal instars of the predator Macrolophus pygmaeus Rambur (Hemiptera: Miridae) are described and illustrated. The changes of the egg as observed from outside the plant tissue during incubation and the eclosion process are also described. A key for the separation of the nymphal instars is given based on the relative length of the third and fourth antennal segments and the relative length of wing pads. Changes in the colour of the adult, from its emergence until it has obtained its final colour are also described.

Partial consumption of different species of aphid prey by the predator Macrolophus pygmaeus (Hemiptera: Miridae)

The partial consumption of prey refers to when a predator does not consume all the digestible biomass of an animal it has killed. The frequency of partial consumption of prey by the polyphagous predator Macrolophus pygmaeus (Hemiptera: Miridae) was recorded for different species of prey and prey population structures, in single and mixed prey species patches. All the instars of the aphid, Aphis gossypii, were provided as prey alone or together with Myzus persicae or Macrosiphum euphorbiae. Numbers killed were determined when equal (10 nymphs of each instar, 40 in total) or unequal numbers (higher numbers of young nymphs but again 40 in total) of nymphs were placed on an eggplant leaf in a plastic Petri dish. In each dish a single 5th instar nymph of the predator was introduced and the numbers killed and numbers of partially consumed aphids were recorded after 24h, at 25 ± 1°C. The numbers of A. gossypii killed were higher than those of the other species of prey used. The frequency of partially consumed prey was highest when A. gossypii was offered alone in equal numbers of each instar, followed by when A. gossypii was provided together with M. persicae in unequal numbers of instars (23.6% and 11.2%, of the total mortality, respectively). Killed but not consumed prey was also recorded, at frequencies that reached 10.7% of the total mortality when A. gossypii was provided alone in equal numbers of each instar. For M. persicae and M. euphorbiae, these percentages were significantly lower. The higher frequency of this behaviour when A. gossypii was the prey may be related to its lower nutritional quality for the predator. The effect of prey instar was not significant. These results indicate that in determining the numbers killed by a predator, partially consumed prey may make up a significant part of the total kill and thus should be taken into consideration.

High population densities of Macrolophus pygmaeus on tomato plants can cause economic fruit damage: interaction with Pepino mosaic virus?

The zoophytophagous predator Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a successful biocontrol agent against several pest species in protected tomato crops. This predator is considered to be harmless for the crop. However, in recent years, Heteroptera feeding punctures on tomato fruit in Belgian and Dutch greenhouses have been misinterpreted as Pepino mosaic virus (PepMV) symptoms. In this study, three hypotheses were tested: (1) M. pygmaeus causes fruit damage that increases with population density and surpasses economic thresholds; (2) the presence of prey or alternative prey reduces the damage; (3) an infection of the tomato plants by PepMV triggers or aggravates M. pygmaeus fruit damage. At increasing M. pygmaeus densities, the severity of fruit damage increased from a few dimples towards yellowish discoloration and deformed fruits. A correlation with an infection with PepMV was found. The severity of the symptoms was independent of the presence of prey. A minimum economic density threshold was estimated at 0.32 M. pygmaeus per leaf. M. pygmaeus can cause economic damage to tomato fruits at densities common in practice. An infection of the plants with PepMV enhances fruit symptoms significantly. Interacting plant defence responses are most likely the key to explaining this, although confirmation is required. © 2015 Society of Chemical Industry.

Effect of plant nitrogen and water status on the foraging behavior and fitness of an omnivorous arthropod.

Omnivorous arthropods make dietary choices according to the environment in which they forage, mainly availability/quality of plant and/or prey resources. Such decisions and their subsequent impacts on life‐history traits may be affected by the availability of nutrients and water to plants, that is, through bottom‐up forces. By setting up arenas for feeding behavior observation as well as glasshouse cages for plant preference assessment, we studied effects of the presence of prey (Lepidoptera eggs) and nitrogen/water availability to host tomato plants on the foraging behavior and life‐history traits in the omnivorous predator Macrolophus pygmaeus (Heteroptera: Miridae). In the absence of prey, the predator fed equally on the plants treated with various levels of nitrogen and water. In the presence of prey, however, the feeding rate on plants decreased when the plant received low water input. The feeding rate on prey was positively correlated with feeding rate on plants; that is, prey feeding increased with plant feeding when the plants received high water input. Moreover, plants receiving high water input attracted more M. pygmaeus adults compared with those receiving low water input. For M. pygmaeus fitness, the presence of prey enhanced its fertility and longevity, but the longevity decreased when plants received low compared with high water input. In conclusion, the omnivorous predator may be obliged to feed on plants to obtain water, and plant water status may be a limiting factor for the foraging behavior and fitness of the omnivorous predator.

Tuta absoluta-induced plant volatiles: attractiveness towards the generalist predator Macrolophus pygmaeus

One of the most damaging insect pests to tomato crops is the tomato leafminer, Tuta absoluta. Current control methods are not efficient at regulating this pest below the economic threshold, leading to the development of new strategies based on its natural enemies. In this study, we evaluated the ability of Macrolophus pygmaeus to discriminate T. absoluta-infested plants versus non-infested tomato plants. We subsequently collected volatile organic chemicals released by tomato plants under different levels of infestation, and identified the associated herbivore-induced plant volatiles (HIPVs). Behavioural assays were conducted in a double-choice olfactometer and flight tunnel. In both systems, M. pygmaeus was significantly attracted towards infested plants. Because distance attraction is likely to be mediated, at least partially, by volatile organic compounds, HIPVs were collected from healthy and infested plants using a dynamic volatile collection system. Volatile chemical profiles vary with the level of infestation; specifically, twice as many chemicals were identified under infestation by 20 T. absoluta larvae compared to healthy plants. A total of 35 compounds were identified, with β-phellandrene, 2-carene, β-caryophyllene, α-pinene and α-phellandrene representing 76–86 % of the total blend. The release of monoterpenes was strongly influenced by the level of caterpillar infestation, while the amount of sesquiterpenes did not vary significantly. We hypothesise that certain HIPVs, most likely monoterpenes, are involved in prey location by M. pygmaeus and have potential to manipulate the natural enemies of T. absoluta to enhance the control of this crop pest.

Nitrogen and water limitations in tomato plants trigger negative bottom-up effects on the omnivorous predator Macrolophus pygmaeus

Omnivorous Heteroptera predators play important roles in biological control of a wide range of pest insects. Their predation could be influenced by various biotic or abiotic factors. Here we examined the effects of nitrogen and water inputs to tomato plants (Solanum lycopersicum L.) on the predation strength of the omnivore Macrolophus pygmaeus Wagner (Hemiptera: Miridae) on eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). We tested the hypothesis that a change in plant status, manipulated by sub-optimal nutrients and water inputs, may influence predation on E. kuehniella by the predator M. pygmaeus. Nitrogen and water restrictions depressed the predation of E. kuehniella eggs by M. pygmaeus. Moreover, we observed a 30 % reduction in predator longevity on plants under low water inputs. Therefore, the negative bottom-up effect of nitrogen and water limitations (in tomato plants) toward M. pygmaeus may be detrimental for mirid predator-based IPM programs in tomato crops.

Beyond Predation: The Zoophytophagous Predator Macrolophus pygmaeus Induces Tomato Resistance against Spider Mites.

Many predatory insects that prey on herbivores also feed on the plant, but it is unknown whether plants affect the performance of herbivores by responding to this phytophagy with defence induction. We investigate whether the prior presence of the omnivorous predator Macrolophus pygmaeus (Rambur) on tomato plants affects plant resistance against two different herbivore species. Besides plant-mediated effects of M. pygmaeus on herbivore performance, we examined whether a plant defence trait that is known to be inducible by herbivory, proteinase inhibitors (PI), may also be activated in response to the interactions of this predator with the tomato plant. We show that exposing tomato plants to the omnivorous predator M. pygmaeus reduced performance of a subsequently infesting herbivore, the two-spotted spider mite Tetranychus urticae Koch, but not of the greenhouse whitefly Trialeurodes vaporariorum (Westwood). The spider-mite infested tomato plants experience a lower herbivore load, i.e., number of eggs deposited and individuals present, when previously exposed to the zoophytophagous predator. This effect is not restricted to the exposed leaf and persists on exposed plants for at least two weeks after the removal of the predators. The decreased performance of spider mites as a result of prior exposure of the plant to M. pygmaeus is accompanied by a locally and systemically increased accumulation of transcripts and activity of proteinase inhibitors that are known to be involved in plant defence. Our results demonstrate that zoophytophagous predators can induce plant defence responses and reduce herbivore performance. Hence, the suppression of populations of certain herbivores via consumption may be strengthened by the induction of plant defences by zoophytophagous predators.

Effect of a plant fortifier (Boundary) on pests and predators of greenhouse vegetable crops

Boundary, a plant fortifier composed of extracts of Sophora flavescens Aiton and brown algae, was tested for control of the leaf miner Tuta absoluta (Meyrick) on tomato (three trials) and of the red spider mite Tetranychus urticae Koch on eggplant (one trial) and for side effects on the whitefly predator Macrolophus pygmaeus (Kambur) (two trials) on tomato and on the thrips predators Orius laevigatus (Fieber) and Amblyseius swirskii Athias-Henriot (two trials) on pepper, all in cold greenhouses in South Italy. Control rates for T. absoluta were moderate (40–70%) in the autumn crop but very high and comparable to those for emamectin benzoate in the spring crops (96–100%). Boundary compared well with abamectin against T. urticae, with near complete control. M. pygmaeus was moderately injured in late autumn, but not in early autumn. At the tested application rate and predator population density Boundary was safe for O. laevigatus and A. swirskii.