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First massive occurrence of greenhouse whitefly parasitoid, Encarsia formosa Gahan (Hymenoptera: Aphelinidae) on greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) in Slovenia

First massive occurrence of greenhouse whitefly parasitoid, Encarsia formosa Gahan (Hymenoptera:... IZVLECEK In 2008, massive population of parasitoid Encarsia formosa was found for the first time in the greenhouses on the Laboratory Field of Biotechnical Faculty in Ljubljana (Slovenia). This species is known for a long time as effective natural enemy of the greenhouse whitefly, Trialeurodes vaporariorum, and other whiteflies in different parts of the world. 1306 wasps from genus Encarsia were found in nymphs of greenhouse whitefly. The most numerous was E. formosa (934 individuals), following by 367 individuals of E. tricolor, 4 males of E. inaron and a male of E. longicornis. Greenhouse whitefly parasitoid was determined on 14 host plants in the greenhouse and E. tricolor on 11 host plants in the greenhouse and on one host plant in the field. E. inaron and E. longicornis appeared only on one host plant in a greenhouse. For the time being the use of wasp E. formosa is not yet permitted in controlling greenhouse whitefly in Slovenia, but there is possibility to include it in the programs of biological control of pests on ornamentals and vegetable plants in the greenhouses. Consequently, the use of chemical insecticides will be reduced. Key words: greenhouse whitefly parasitoid, Encarsia formosa, greenhouse whitefly, Trialeurodes vaporariorum, biological control, natural enemies, indigenous species, greenhouse, Slovenia PRVA STEVILCNEJSA NAJDBA NAJEZDNIKA RASTLINJAKOVEGA SCITKARJA, Encarsia formosa Gahan (Hymenoptera: Aphelinidae) NA RASTLINJAKOVEM SCITKARJU, Trialeurodes vaporariorum [Westwood] (Homoptera: Aleyrodidae) V SLOVENIJI V rastlinjakih na Laboratorijskem polju Biotehniske fakultete v Ljubljani smo v letu 2008 prvic nasli stevilcnejso populacijo parazitoida Encarsia formosa, ki je v svetu dobro znan naravni sovraznik rastlinjakovega scitkarja, Trialeurodes vaporariorum, in nekaterih drugih vrst scitkarjev. V licinkah rastlinjakovega scitkarja smo nasli 1306 osic iz rodu Encarsia. Najbolj stevilcni so bili osebki vrste E. formosa (934 osebkov), nasli pa smo se 367 osebkov vrste E. tricolor, 4 samce vrste E. inaron in enega samca vrste E. longicornis. Predstavnike vrste E. formosa smo nasli na 14 gostiteljskih rastlinah v rastlinjakih, vrsto E. tricolor pa na 11 vrstah gostiteljskih rastlin v rastlinjakih in na eni rastlinski vrsti na prostem, medtem ko sta se vrsti E. inaron in E. longicornis pojavili le na eni rastlinski vrsti v rastlinjaku. V Sloveniji uporaba osice E. formosa za zatiranje rastlinjakovega scitkarja se ni razsirjena, vendar bi jo lahko vkljucili v programe bioticnega varstva okrasnih rastlin in vrtnin v zavarovanih prostorih in tako zmanjsali uporabo insekticidov. Kljucne besede: najezdnik rastlinjakovega scitkarja, Encarsia formosa, rastlinjakov scitkar, Trialeurodes vaporariorum, bioticno varstvo, naravni sovrazniki, domorodna vrsta, rastlinjak, Slovenija Teach. Assist., B. Sc., Jamnikarjeva 101, SI-1111 Ljubljana; E-mail: katarina.kos@bf.uni-lj.si Assoc. Prof., Ph. D., University of Belgrade, Faculty of Biology, Studentski trg 16, SER-11000 Belgrade Teach. Assist., young reseacher, Jamnikarjeva 101, SI-1111 Ljubljana Teach. Assist., Ph. D., ibid. Assoc. Prof., Ph. D., ibid, str. 285 - 291 1 INTRODUCTION Family of whiteflies (Aleyrodidae) comprises important pests, which attack many cultivated and wild-growing plant species in the open and in the greenhouses. They have incomplete development and adults are around 2 mm in length and have totally white wings, which are covered with waxy coating (Peters, 1993; Succop, 1997). Greenhouse whitefly, Trialeurodes vaporariorum (Westwood), causes direct damage with sucking sap from the plants, resulting in a yellow mottling on the surface of the leaf, as well as leaf loss, wilting and stunting. Its indirect damage is made by transmission of viruses and producing honeydew, which attract black fungi of sooty molds, Cladosporium spp. (Succop, 1997). Parasitoids from genus Encarsia are probably one of the first practically applied biological agents in plant protection. Genus Encarsia belongs to subfamily Aphelinidae, family Braconidae and order Hymenoptera. Encarsia formosa Gahan is a parasitoid, which is, as biological agent in controlling greenhouse whitefly (Fig.3), spread in different parts of the world (van Lenteren and Woets, 1988; van Lenteren et al., 1996). It is used against this pest on vegetable and ornamental plants in greenhouses. Commercial usage of this parasitoid started already around 1920, but after approximately 20 years its interest waned due to intensive development of chemical insecticides. After 1970, interest in greenhouse whitefly parasitoid was reinitiated and its usage in plant protection was expanded in 1993 to 4800 hectares of greenhouse area (van Lenteren and Woets, 1988; van Lenteren, 1995). Adult wasps of parasitoid (Fig. 1) feed on honeydew and with excreted body fluids of young larvae (L1) of greenhouse whitefly, and doing so they kill them many. If many wasps appear, previously mentioned way of feeding is used also on higher developmental stages of whitefly larvae. To feed host, Encarsia formosa wasps wound larvae by probing with the ovipositor and feeds from wounds and that way they are provided with proteins. In this way they kill almost ¾ of whiteflies. Larvae of Encarsia formosa feed with the internal content of parasitized whiteflies, eat all the organs and leave only outer armor (Fig. 2) in which they pupate afterward (Milevoj, 2007). Figure 1: Adult of Encarsia formosa Gahan (Photo by K. Kos) 286 Figure 2: Empty pupal cases of greenhouse whitefly on celery (Photo by K. Kos) Figure 3: Life cycle of Encarsia formosa Gahan on greenhouse whitefly (Photo by K. Kos) Encarsia formosa parasitizes at least 15 whitefly species, which belong to 8 genera. The most important hosts of this natural enemy are Trialeurodes vaporariorum, Aleyrodes proletella (L.), Bemisia argentifolii Bellows & Perring and Bemisia tabaci (Gennadius) (Schauff and Evans, 1996), but on the other hand greenhouse whitefly parasitoid is also parasitized by three hyperparasitoids: Signiphora coquilletti Ashmead (Woolley and Vet, 1981), Encarsia pergandiella Howard (Buijs et al., 1981) and Encarsia tricolor Förster. The later can be also a primary parasitoid, autoparasitoid or hyperparasitoid (Avilla et al., 1991). In August 1994, Encarsia formosa was first recorded in Slovenia, namely on tomato plants grown on Laboratory Field of Biotechnical Faculty in Ljubljana, which were heavily attacked by greenhouse whitefly (Milevoj and Osvald, 1996). But in years which followed, this natural enemy was impossible to find. Target plants which are mentioned by Milevoj and Osvald (1996) as most suitable for introduction of Encarsia formosa are pepper, egg plant, bean, cucumber, tomato and rose. It is very important to monitor the first attack of greenhouse whitefly with yellow sticky boards or indicator plants, which are put into the greenhouse with the aim of easier detection of the pest. Among such plant species we can also include fuchsia plants (Fuchsia spp.), which have ability of attracting first specimens of whitefly in the greenhouse. The effect of biological control is seen after around 3 weeks. But the strategy of plant protection must be harmonized in a greenhouse. Namely, the wasp is very sensitive to multiple application of fungicides and also foliage fertilizers can do harm to it (Milevoj, 2007). The aim of our research was to find the indigenous species of natural enemies in greenhouses in Slovenia and in nymphs of greenhouse whitefly from greenhouses on Laboratory Field of Biotechnical Faculty in Ljubljana the high number of greenhouse whitefly parasitoid, Encarsia formosa Gahan, and some other Encarsia members was found. 2 MATERIAL AND METHODS At the end of summer 2008 we investigated the presence of parasitoids on greenhouse whitefly, Trialeurodes vaporariorum, in a greenhouse on Laboratory Field of Biotechnical Faculty in Ljubljana (46o04' N, 14o31' E). Vegetables, ornamental plants and weeds from the glass and plastic greenhouses were included in a research. One random sample was taken also from the cabbage, attacked by cabbage whitefly, Aleyrodes proletella L., grown in the open (village Trstenik near Golnik, 46°20' N, 14°20 E). The sampling method was adapted to the development of parasitoids inside their hosts. We placed parasitized pupal cases of greenhouse whitefly together with the host plant into the plastic pots, similar as we collected the samples of aphid parasitoids (Brajkovi and Tomanovi, 2005; Kos, 2007; Kos et al., 2008). After 3 to 4 weeks we removed dead parasitoids from genus Encarsia from the labeled samples. The samples were sent to Natural History Museum in Belgrade (Serbia) for identification (Aleksandar Stojanovi). 3 RESULTS WITH DISCUSSION In the greenhouses on the Laboratory Field of Biotechnical Faculty, the parasitoids of greenhouse whitefly were found in high number. We collected 14 plant species, on which black pupal cases of whiteflies were observed and for which we assumed to be parasitized. The total number of female wasps had amounted 1306 individuals. Encarsia formosa was the most abundant (934 individuals), namely 930 females and 4 males were identified from the samples (Table 1). The second most abundant species was Encarsia tricolor Förster with 367 individuals, from which 145 were females and 222 were males. We also found 4 males of Encarsia inaron (Walker) and a male of Encarsia longicornis Mercet. Parasitoid Encarsia formosa was found on 14 host plants from the greenhouse (Fig. 4) and Encarsia tricolor on 11 host plants from the greenhouse and on cabbage in the open. Encarsia inaron and Encarsia longicornis appeared only on one host plant, i.e. tomato and cherry tomato, respectively, both from the greenhouse. One male and 3 females of Encarsia tricolor was collected also from the nymphs of cabbage whitefly, which attacked cabbage (Brassica oleracea var. capitata) in village Trstenik near Golnik. 288 Table 1: Encarsia species and number of their males and females from greenhouse whitefly, Trialeurodes vaporariorum, collected from 14 different host plants of the pest. The samples were taken from the greenhouses on the Laboratory Field of Biotechnical Faculty in Ljubljana, Slovenia. Common name St John's wort Common buckwheat Tomato Basil Common chicory Celery Cherry tomato Fuchsia Bean Asparagus Marjoram Holy basil Cucumber Pepper Host plant Latin name Hypericum perforatum L. Fagopyrum esculentum Moench Lycopersicon esculentum Mill. Ocimum polystachion L. Cichorium intybus L. Apium graveolens L. Lycopersicon esculentum Mill. Fuchsia spp. Phaseolus vulgaris L. Asparagus officinalis L. Majorana hortensis Moench Ocimum sanctum L. Cucumis sativa L. Capsicum annuum L. Parasitoid Number of males Encarsia formosa Gahan 1 Encarsia tricolor Förster 50 Encarsia formosa Gahan Species Encarsia formosa Gahan Encarsia tricolor Förster Encarsia inaron (Walker) Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia formosa Gahan Encarsia tricolor Förster Encarsia longicornis Mercet Encarsia formosa Gahan Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster 51 4 1 105 2 1 1 3 38 2 8 26 18 13 20 70 4 1 11 8 76 10 23 19 85 187 6 Number of females 112 45 208 35 62 Total 113 50 45 208 86 4 62 1 105 2 10 23 20 1 85 190 38 6 2 8 26 70 22 1 24 8 96 Figure 4: Host plants of greenhouse whitefly, Trialeurodes vaporariorum, from the greenhouses, in which greenhouse whitefly parasitoid, Encarsia formosa, was found. Figure 5: Host plants of greenhouse whitefly, Trialeurodes vaporariorum, from the greenhouses, in which Encarsia tricolor was found. The same parasitoid was recored also on cabbage, attacked by cabbage whitefly, Aleyrodes proletella. 4 CONCLUSIONS In 2008, high number of parasitoid wasps from genus Encarsia was found on vegetables and ornamental plants in greenhouses on Laboratory Field of Biotechnical Faculty in Ljubljana. Encarsia formosa, which is considered to be one of the most important biological agent in controlling whiteflies in greenhouses (Hoddle, 1997), was the most abundant Encarsia species in our research. Most often it is used in controlling greenhouse whitefly, Trialeurodes vaporariorum, and tobacco whitefly, Bemisia tabaci (Hoddle et al., 1998). Entire number of wasps, we found, was 1308, from which 934 individuals belonged to the species Encarsia formosa (930 females and 4 males) and 367 individuals were identified as Encarsia tricolor (145 females and 222 males). We also recorded 4 males of Encarsia inaron and a male of Encarsia longicornis. We ascertained Encarsia formosa on 14 different host plants in greenhouse and Encarsia tricolor on 11 host plants in greenhouse and on cabbage, which was grown outdoor in village Trstenik in Gorenjska region. Greenhouse whitefly represents large problems in growing vegetables and ornamental plants in greenhouses in Slovenia. For this reason the use of Encarsia formosa in a frame of integrated plant protection against the pest mentioned could be practiced as an important measure in reducing damage. Introduction of parasitoid E. formosa is relatively simple and this biological control agent can effectively reduce the population of whitefly. Use of E. formosa is a good example of reduction of damage, caused by greenhouse whitefly, and at the same time there is no need for relying solely on insecticides (Succop, 1997). 5 ACKNOWLEDGEMENT This work was done within Horticulture No P4-00130481, a program funded by the Slovenian Research Agency, and within the project CRP V4-0524 granted by Slovenian Research Agency and Ministry of Agriculture, Food and Forestry of R Slovenia. Part of the research was funded within Professional tasks from the field of plant protection, the program funded by the Ministry of Agriculture, Forestry and Food of R Slovenia Phytosanitary Administration of the Republic of Slovenia. 290 6 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Acta Agriculturae Slovenica de Gruyter

First massive occurrence of greenhouse whitefly parasitoid, Encarsia formosa Gahan (Hymenoptera: Aphelinidae) on greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) in Slovenia

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de Gruyter
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1581-9175
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Abstract

IZVLECEK In 2008, massive population of parasitoid Encarsia formosa was found for the first time in the greenhouses on the Laboratory Field of Biotechnical Faculty in Ljubljana (Slovenia). This species is known for a long time as effective natural enemy of the greenhouse whitefly, Trialeurodes vaporariorum, and other whiteflies in different parts of the world. 1306 wasps from genus Encarsia were found in nymphs of greenhouse whitefly. The most numerous was E. formosa (934 individuals), following by 367 individuals of E. tricolor, 4 males of E. inaron and a male of E. longicornis. Greenhouse whitefly parasitoid was determined on 14 host plants in the greenhouse and E. tricolor on 11 host plants in the greenhouse and on one host plant in the field. E. inaron and E. longicornis appeared only on one host plant in a greenhouse. For the time being the use of wasp E. formosa is not yet permitted in controlling greenhouse whitefly in Slovenia, but there is possibility to include it in the programs of biological control of pests on ornamentals and vegetable plants in the greenhouses. Consequently, the use of chemical insecticides will be reduced. Key words: greenhouse whitefly parasitoid, Encarsia formosa, greenhouse whitefly, Trialeurodes vaporariorum, biological control, natural enemies, indigenous species, greenhouse, Slovenia PRVA STEVILCNEJSA NAJDBA NAJEZDNIKA RASTLINJAKOVEGA SCITKARJA, Encarsia formosa Gahan (Hymenoptera: Aphelinidae) NA RASTLINJAKOVEM SCITKARJU, Trialeurodes vaporariorum [Westwood] (Homoptera: Aleyrodidae) V SLOVENIJI V rastlinjakih na Laboratorijskem polju Biotehniske fakultete v Ljubljani smo v letu 2008 prvic nasli stevilcnejso populacijo parazitoida Encarsia formosa, ki je v svetu dobro znan naravni sovraznik rastlinjakovega scitkarja, Trialeurodes vaporariorum, in nekaterih drugih vrst scitkarjev. V licinkah rastlinjakovega scitkarja smo nasli 1306 osic iz rodu Encarsia. Najbolj stevilcni so bili osebki vrste E. formosa (934 osebkov), nasli pa smo se 367 osebkov vrste E. tricolor, 4 samce vrste E. inaron in enega samca vrste E. longicornis. Predstavnike vrste E. formosa smo nasli na 14 gostiteljskih rastlinah v rastlinjakih, vrsto E. tricolor pa na 11 vrstah gostiteljskih rastlin v rastlinjakih in na eni rastlinski vrsti na prostem, medtem ko sta se vrsti E. inaron in E. longicornis pojavili le na eni rastlinski vrsti v rastlinjaku. V Sloveniji uporaba osice E. formosa za zatiranje rastlinjakovega scitkarja se ni razsirjena, vendar bi jo lahko vkljucili v programe bioticnega varstva okrasnih rastlin in vrtnin v zavarovanih prostorih in tako zmanjsali uporabo insekticidov. Kljucne besede: najezdnik rastlinjakovega scitkarja, Encarsia formosa, rastlinjakov scitkar, Trialeurodes vaporariorum, bioticno varstvo, naravni sovrazniki, domorodna vrsta, rastlinjak, Slovenija Teach. Assist., B. Sc., Jamnikarjeva 101, SI-1111 Ljubljana; E-mail: katarina.kos@bf.uni-lj.si Assoc. Prof., Ph. D., University of Belgrade, Faculty of Biology, Studentski trg 16, SER-11000 Belgrade Teach. Assist., young reseacher, Jamnikarjeva 101, SI-1111 Ljubljana Teach. Assist., Ph. D., ibid. Assoc. Prof., Ph. D., ibid, str. 285 - 291 1 INTRODUCTION Family of whiteflies (Aleyrodidae) comprises important pests, which attack many cultivated and wild-growing plant species in the open and in the greenhouses. They have incomplete development and adults are around 2 mm in length and have totally white wings, which are covered with waxy coating (Peters, 1993; Succop, 1997). Greenhouse whitefly, Trialeurodes vaporariorum (Westwood), causes direct damage with sucking sap from the plants, resulting in a yellow mottling on the surface of the leaf, as well as leaf loss, wilting and stunting. Its indirect damage is made by transmission of viruses and producing honeydew, which attract black fungi of sooty molds, Cladosporium spp. (Succop, 1997). Parasitoids from genus Encarsia are probably one of the first practically applied biological agents in plant protection. Genus Encarsia belongs to subfamily Aphelinidae, family Braconidae and order Hymenoptera. Encarsia formosa Gahan is a parasitoid, which is, as biological agent in controlling greenhouse whitefly (Fig.3), spread in different parts of the world (van Lenteren and Woets, 1988; van Lenteren et al., 1996). It is used against this pest on vegetable and ornamental plants in greenhouses. Commercial usage of this parasitoid started already around 1920, but after approximately 20 years its interest waned due to intensive development of chemical insecticides. After 1970, interest in greenhouse whitefly parasitoid was reinitiated and its usage in plant protection was expanded in 1993 to 4800 hectares of greenhouse area (van Lenteren and Woets, 1988; van Lenteren, 1995). Adult wasps of parasitoid (Fig. 1) feed on honeydew and with excreted body fluids of young larvae (L1) of greenhouse whitefly, and doing so they kill them many. If many wasps appear, previously mentioned way of feeding is used also on higher developmental stages of whitefly larvae. To feed host, Encarsia formosa wasps wound larvae by probing with the ovipositor and feeds from wounds and that way they are provided with proteins. In this way they kill almost ¾ of whiteflies. Larvae of Encarsia formosa feed with the internal content of parasitized whiteflies, eat all the organs and leave only outer armor (Fig. 2) in which they pupate afterward (Milevoj, 2007). Figure 1: Adult of Encarsia formosa Gahan (Photo by K. Kos) 286 Figure 2: Empty pupal cases of greenhouse whitefly on celery (Photo by K. Kos) Figure 3: Life cycle of Encarsia formosa Gahan on greenhouse whitefly (Photo by K. Kos) Encarsia formosa parasitizes at least 15 whitefly species, which belong to 8 genera. The most important hosts of this natural enemy are Trialeurodes vaporariorum, Aleyrodes proletella (L.), Bemisia argentifolii Bellows & Perring and Bemisia tabaci (Gennadius) (Schauff and Evans, 1996), but on the other hand greenhouse whitefly parasitoid is also parasitized by three hyperparasitoids: Signiphora coquilletti Ashmead (Woolley and Vet, 1981), Encarsia pergandiella Howard (Buijs et al., 1981) and Encarsia tricolor Förster. The later can be also a primary parasitoid, autoparasitoid or hyperparasitoid (Avilla et al., 1991). In August 1994, Encarsia formosa was first recorded in Slovenia, namely on tomato plants grown on Laboratory Field of Biotechnical Faculty in Ljubljana, which were heavily attacked by greenhouse whitefly (Milevoj and Osvald, 1996). But in years which followed, this natural enemy was impossible to find. Target plants which are mentioned by Milevoj and Osvald (1996) as most suitable for introduction of Encarsia formosa are pepper, egg plant, bean, cucumber, tomato and rose. It is very important to monitor the first attack of greenhouse whitefly with yellow sticky boards or indicator plants, which are put into the greenhouse with the aim of easier detection of the pest. Among such plant species we can also include fuchsia plants (Fuchsia spp.), which have ability of attracting first specimens of whitefly in the greenhouse. The effect of biological control is seen after around 3 weeks. But the strategy of plant protection must be harmonized in a greenhouse. Namely, the wasp is very sensitive to multiple application of fungicides and also foliage fertilizers can do harm to it (Milevoj, 2007). The aim of our research was to find the indigenous species of natural enemies in greenhouses in Slovenia and in nymphs of greenhouse whitefly from greenhouses on Laboratory Field of Biotechnical Faculty in Ljubljana the high number of greenhouse whitefly parasitoid, Encarsia formosa Gahan, and some other Encarsia members was found. 2 MATERIAL AND METHODS At the end of summer 2008 we investigated the presence of parasitoids on greenhouse whitefly, Trialeurodes vaporariorum, in a greenhouse on Laboratory Field of Biotechnical Faculty in Ljubljana (46o04' N, 14o31' E). Vegetables, ornamental plants and weeds from the glass and plastic greenhouses were included in a research. One random sample was taken also from the cabbage, attacked by cabbage whitefly, Aleyrodes proletella L., grown in the open (village Trstenik near Golnik, 46°20' N, 14°20 E). The sampling method was adapted to the development of parasitoids inside their hosts. We placed parasitized pupal cases of greenhouse whitefly together with the host plant into the plastic pots, similar as we collected the samples of aphid parasitoids (Brajkovi and Tomanovi, 2005; Kos, 2007; Kos et al., 2008). After 3 to 4 weeks we removed dead parasitoids from genus Encarsia from the labeled samples. The samples were sent to Natural History Museum in Belgrade (Serbia) for identification (Aleksandar Stojanovi). 3 RESULTS WITH DISCUSSION In the greenhouses on the Laboratory Field of Biotechnical Faculty, the parasitoids of greenhouse whitefly were found in high number. We collected 14 plant species, on which black pupal cases of whiteflies were observed and for which we assumed to be parasitized. The total number of female wasps had amounted 1306 individuals. Encarsia formosa was the most abundant (934 individuals), namely 930 females and 4 males were identified from the samples (Table 1). The second most abundant species was Encarsia tricolor Förster with 367 individuals, from which 145 were females and 222 were males. We also found 4 males of Encarsia inaron (Walker) and a male of Encarsia longicornis Mercet. Parasitoid Encarsia formosa was found on 14 host plants from the greenhouse (Fig. 4) and Encarsia tricolor on 11 host plants from the greenhouse and on cabbage in the open. Encarsia inaron and Encarsia longicornis appeared only on one host plant, i.e. tomato and cherry tomato, respectively, both from the greenhouse. One male and 3 females of Encarsia tricolor was collected also from the nymphs of cabbage whitefly, which attacked cabbage (Brassica oleracea var. capitata) in village Trstenik near Golnik. 288 Table 1: Encarsia species and number of their males and females from greenhouse whitefly, Trialeurodes vaporariorum, collected from 14 different host plants of the pest. The samples were taken from the greenhouses on the Laboratory Field of Biotechnical Faculty in Ljubljana, Slovenia. Common name St John's wort Common buckwheat Tomato Basil Common chicory Celery Cherry tomato Fuchsia Bean Asparagus Marjoram Holy basil Cucumber Pepper Host plant Latin name Hypericum perforatum L. Fagopyrum esculentum Moench Lycopersicon esculentum Mill. Ocimum polystachion L. Cichorium intybus L. Apium graveolens L. Lycopersicon esculentum Mill. Fuchsia spp. Phaseolus vulgaris L. Asparagus officinalis L. Majorana hortensis Moench Ocimum sanctum L. Cucumis sativa L. Capsicum annuum L. Parasitoid Number of males Encarsia formosa Gahan 1 Encarsia tricolor Förster 50 Encarsia formosa Gahan Species Encarsia formosa Gahan Encarsia tricolor Förster Encarsia inaron (Walker) Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia formosa Gahan Encarsia tricolor Förster Encarsia longicornis Mercet Encarsia formosa Gahan Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster Encarsia formosa Gahan Encarsia tricolor Förster 51 4 1 105 2 1 1 3 38 2 8 26 18 13 20 70 4 1 11 8 76 10 23 19 85 187 6 Number of females 112 45 208 35 62 Total 113 50 45 208 86 4 62 1 105 2 10 23 20 1 85 190 38 6 2 8 26 70 22 1 24 8 96 Figure 4: Host plants of greenhouse whitefly, Trialeurodes vaporariorum, from the greenhouses, in which greenhouse whitefly parasitoid, Encarsia formosa, was found. Figure 5: Host plants of greenhouse whitefly, Trialeurodes vaporariorum, from the greenhouses, in which Encarsia tricolor was found. The same parasitoid was recored also on cabbage, attacked by cabbage whitefly, Aleyrodes proletella. 4 CONCLUSIONS In 2008, high number of parasitoid wasps from genus Encarsia was found on vegetables and ornamental plants in greenhouses on Laboratory Field of Biotechnical Faculty in Ljubljana. Encarsia formosa, which is considered to be one of the most important biological agent in controlling whiteflies in greenhouses (Hoddle, 1997), was the most abundant Encarsia species in our research. Most often it is used in controlling greenhouse whitefly, Trialeurodes vaporariorum, and tobacco whitefly, Bemisia tabaci (Hoddle et al., 1998). Entire number of wasps, we found, was 1308, from which 934 individuals belonged to the species Encarsia formosa (930 females and 4 males) and 367 individuals were identified as Encarsia tricolor (145 females and 222 males). We also recorded 4 males of Encarsia inaron and a male of Encarsia longicornis. We ascertained Encarsia formosa on 14 different host plants in greenhouse and Encarsia tricolor on 11 host plants in greenhouse and on cabbage, which was grown outdoor in village Trstenik in Gorenjska region. Greenhouse whitefly represents large problems in growing vegetables and ornamental plants in greenhouses in Slovenia. For this reason the use of Encarsia formosa in a frame of integrated plant protection against the pest mentioned could be practiced as an important measure in reducing damage. Introduction of parasitoid E. formosa is relatively simple and this biological control agent can effectively reduce the population of whitefly. Use of E. formosa is a good example of reduction of damage, caused by greenhouse whitefly, and at the same time there is no need for relying solely on insecticides (Succop, 1997). 5 ACKNOWLEDGEMENT This work was done within Horticulture No P4-00130481, a program funded by the Slovenian Research Agency, and within the project CRP V4-0524 granted by Slovenian Research Agency and Ministry of Agriculture, Food and Forestry of R Slovenia. Part of the research was funded within Professional tasks from the field of plant protection, the program funded by the Ministry of Agriculture, Forestry and Food of R Slovenia Phytosanitary Administration of the Republic of Slovenia. 290 6

Journal

Acta Agriculturae Slovenicade Gruyter

Published: Sep 1, 2009

References