Macrolophus caliginosus is a species of true bug in the family Miridae. It is omnivorous and both preys on insects and feeds on plant tissues. It is used in Europe in the biological control of whitefly in tomatoes grown under glass. Its eyes are red, its antennae are green with a black base and its legs are long, enabling it to move rapidly. The nymphs are yellowish-green. The eggs of M.

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Omnivorous mirids Hemiptera: Miridae are unusual as biocontrol agents, as they feed on both plants and pests. Therefore, extensive knowledge of their ecological behavior is required to maximize their predatory side and to minimize crop damage. Macrolophus pygmaeus is a known predator of small arthropods, used in European tomato crops for more than 20 years. This mirid is currently considered harmless to tomato, although some controversy remains in relation to the status of the species.

The aim of this work was to investigate the benefits that M. The experiment was carried out in 6 experimental greenhouses in southern Spain. Two treatments, low and high M. Low and high M. Tomato plants with a lower number of M. A significantly higher proportion of aborted flowers and fruits was registered in greenhouses with higher M.

Yield was also lower in greenhouses with higher mirid populations. The number of fruits harvested did not differ between treatments, but average fruit weight was significantly lower in the greenhouses with higher mirid numbers.

The number of punctures attributed to M. This work shows that M. A deeper understanding of the factors that modulate the zoophytophagous response of this economically important species is needed. Omnivorous mirids Hemiptera: Miridae do not fit the ideal model of predators from a biological pest control perspective as they feed not only on prey but also on plants, thus providing both services and disservices. This point of view has greatly changed in recent decades with several species of mirids being successfully used in the regulation of pest populations, especially on vegetable crops.

Several species of omnivorous mirids, such as dicyphines, are key predators in some vegetable crops e. Dicyphus cerastii Wagner, Dicyphus hesperus Knight, Dicyphus hyalinipennis Burmeister, Dicyphus tamanini Wagner, Macrolophus pygmaeus and Nesidiocoris tenuis Reuter Hemiptera: Miridae have been reported as effective biocontrol agents of small arthropod pests Barnadas et al.

Some of these species i. Dicyphus bolivari Lindberg Hemiptera: Miridae Sanchez and Cassis, , has been assayed recently against Tuta absoluta on tomato crops Ingegno et al. Other species, such as Engytatus modestus Distant and Creontiades pallidus Rambur Hemiptera: Miridae , are known to prey on phytophagous arthropods but have a more prominent plant-feeder character and are thus considered as pests Urbaneja et al.

Nonetheless, the use of omnivorous mirids as predators is not free from controversy and while some species i. Besides the likely subjective level of appreciation, it is undeniable that omnivorous mirids are unusual as predators and management strategies are needed that minimize the negative aspects of their phytophagous character while exploiting their predatory side Albajes and Alomar, ; Sanchez, Like many other heteropterans, mirids use a lacerate and flush feeding method, in which plant or prey tissues are liquified by digestive enzymes and the mechanical actions of stylets to facilitate their ingestion Miles, ; Cohen, ; Wheeler, As phytophgous insects, they feed on the mesophyll of leaves and the ground tissues of stems, inflorescences, and fruits, which are more balanced in nutrients than phloem or xylem Wheeler, Zoophytophagy in mirids is a continuous trait, going from strictly phytophagous species to essentially obligate carnivores Miles, ; Wheeler, ; Cassis and Schuh, In this work, we refer to omnivorous as those species that feed obligatory or facultatively on plants but whose main feeding niche is carnivory.

This is the case for some taxa, such as certain Macrolophus, Dicyphus , and Nesidiocoris species, that are of interest as biological control agents in vegetable crops and feed on both plants and prey, but for whom the contribution of vegetable nutrients to their fitness is generally very low in comparison with animal food Sanchez et al.

Besides, their perfomance varies greatly with the mirid species, host plant, the availability of alternative host plant, and even the plant part McGregor et al. In the most favorable cases, plant feeding allows the insect to complete its development and reproduce but, generally, the nymphal stage lasts much longer and egg-laying is very limited in comparison to when feeding on prey Naranjo and Gibson, ; Perdikis and Lykouressis, ; Sanchez et al.

In consequence, omnivorous mirids consume primarily prey when available and phytophagy, as well as plant injury, increases exponentially when animal food is scarce Sanchez, , ; Sanchez and Lacasa, ; Calvo et al. Injuries produced by omnivorous mirids vary with the organ affected, and with the plant and mirid species.

The greatest impact of mirids derives from flower damage and fruit abortion because, rather than having an impact on the cosmetic appearance of the fruit, it materializes in the yield itself Sanchez and Lacasa, ; Sanchez, This has prompted investigation into the factors that modulate the zoophytophagous response in omnivorous mirids and the development of management strategies to keep populations below critical levels Alomar and Albajes, ; Sanchez and Lacasa, ; Sanchez, ; Sanchez et al.

There have been problems with the identification of Macrolophus species and in many cases M. In this work, we consider that the citations of M. This mirid was originally used for the control of whiteflies but it may potentially prey on other small arthropods - such as thrips, spider mites, leafminers, aphids, and lepidopterans, including the eggs and first instar of T. On the other hand, economic damage has been reported in tomato crops Sampson, ; Sampson and Jacobson, ; Moerkens et al.

The fact is that no conclusive experiments have been carried out to quantify the impact of M. The aim of this work was to investigate the trade-off between the benefits that M. Nothing was grown in these greenhouses in the latest 2 years and during this period they were freed of weeds, both inside and the immediate surroundings. The temperature was controlled independently in each greenhouse by the Mithra Clima System Nutricontrol, S.

The temperature and relative humidity were recorded by the system every minute. There were four rows of 20 tomato plants in each greenhouse; the distance between plants in a row was 0. Tomato seeds cv. Optima, Seminis, Murcia were planted on 1 December and seedlings 25—30 cm high were transplanted on 14 February This tomato cultivar is commonly cultivated in the area. The plants were grown in soil, and were watered and fertilized when needed by drip irrigation.

Due to the small size of the greenhouses and their good ventilation, no pollinator insects were introduced. No pesticides nor fungicides were applied during the entire period of the assay. The effect of M. Two release methods for M. Macrolophus pygmaeus was provided by Bioline Agroscience Essex, France. In direct release, adults of M. The adults of M. In order to improve the establishment of the mirid, the adults of M.

Twenty-four hours later, the 16 tomato plants of each cage, with the adults of M. In pre-release, the same procedure as in direct release was used but the adults of M. The mirids were fed periodically every 3—4 days on Ephestia kuehniella Zeller Lepidoptera: Pyralidae ; a total of 24 g were provided to each of the three cages during the whole period.

The number of M. In both treatments, the tomato plants with the mirids were transplanted in the greenhouses on 27 March ; in the 2 weeks following this, the tomato plants were supplemented with 5 g of E. Bemisia tabaci , provided by Koppert Spain, was introduced twice in all the greenhouses, on 13 March and 21 March , at adults per greenhouse on each date.

Tuta absoluta was not introduced because it invariably colonizes tomato greenhouses in southern Spain Cabello, The nymphs and adults of M. The B. To quantify the impact of M. Besides, the number of fruits and of those that did not fructify was counted in the first available truss with no flowers, when inspecting the plants from top to bottom.

Fruits were harvested on three occasions: 17 and 28 May, and 4 June On the three dates, all the fruits in each greenhouse were counted and weighed. Besides, on 28 May, 50 fruits per greenhouse were chosen at random, weighed, and scored individually for T. Additionally, on 4 June, fruits were harvested individually from 20 randomly selected plants in each greenhouse and processed individually.

They were classified as ripe completely red , about to ripen partially green , or green completely green.

The date of sampling was introduced in the models as a random factor. GLMMs were also used to compare the proportions of aborted flowers and the proportions of aborted fruits on trusses. The data of the abundance of M. The data for T. The number of B. Besides, the data from the processing of single tomato fruits at the second and third harvests were used to compare the number of T.

In the latter analyses, the state of fruit ripening was introduced in the models as a random factor. In all cases, with the exception of T.

In the case of T. In the two treatments the M. Figure 1. Time since the introduction of B. Greenhouses with a lower population of M. The number of T. In the same way, the number of B. The whitefly numbers increased progressively in the two treatments, reaching—on day 62—a maximum of The peak of B. No other whitefly species T. Frankliniella occidentalis Pergande Thysanoptera: Thripidae was observed very occassionally on leaves.

Figure 2. Time since the introduction of Bemisia tabaci. Figure 3. A significantly higher proportion of aborted flowers was registered in greenhouses with higher M.

The proportion of aborted flowers in the greenhouses with lower numbers of mirids was fairly constant and below 1.

The percentage of aborted fruits was highest at the end of the assay, both at high Figure 4.


Macrolophus caliginosus

Predatory bug kills wide range of pests all stages , under certain conditions can save its population feeding on plant sap and pollen. Use to control whitefly greenhouse and tobacco , thrips , tuta absoluta tomato moth. Introduction every 2 weeks during months. Life period about 30 days. Female lays during life, however only eggs survive. Bug has 7 instars: egg.



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