Parasitoid Complex Research Articles

New eurytomid parasitoids of bark beetles in pine plantations in Ihtimanska Sredna Gora Mountains, Bulgaria

In 2020, five eurytomid species were found for first time on bark beetles in Pinus sylvestris plantations in Ihtimanska Sredna Gora Mountains in Bulgaria: Eurytoma afra Boheman, 1836, Eurytoma arctica Thomson, 1875, Eurytoma morio Boheman, 1836, Eurytoma sp.1 and Eurytoma sp.2. One of them, E. arctica is a new species for the Bulgarian fauna. The parasitoids were reared from stem and branch samples infested by Ips acuminatus, Pityogenes bistridentatus, Pityophthorus pityographus, Tomicus piniperda and T. minor. All host-parasitoid associations are new for Bulgaria. In parasitoid complex, the most abundant species was E. morio (75.9%), followed by E. arctica (13.8%), Eurytoma sp. (6.9%) and E. afra (3.4%). The parasitism of the hosts varied between 2.6% (E. afra on I. acuminatus, P. bistridentatus and P. pityographus) and 33.3% (E. morio on I. acuminatus).

Parasitoids (Hymenoptera, Eulophidae, Braconidae) as a mortality factor for the lime leaf miner (<i>Phyllonorycter issikii</i>, Lepidoptera, Gracillariidae) in the Cis-Urals

The assemblage of hymenopteran parasitoids associated with the invasive lime leaf miner, Phyllonorycter issikii (Lepidoptera, Gracillariidae) developing on the lime (Tilia cordata) was studied in the Perm Region and in the Republic of Bashkortostan during 2019. Sixteen species of parasitoids of Ph. issikii were recognized: Diglyphus isaea, Elachertus fenestratus, Hyssopus geniculatus, Pnigalio agraules, P. mediterraneus, Sympiesis dolichogaster, S. gordius, S. sericeicornis, Chrysocharis laomedon, Ch. nephereus, Ch. pentheus, Ch. pubens, Ch. pubicornis, Ch. submutica, Minotetrastichus frontalis (Eulophidae) and Pholetesor circumscriptus (Braconidae). Three species, Diglyphus isaea, Chrysocharis pubens and Ch. submutica (Eulophidae), were reported as parasitoids of the lime leaf miner for the first time. The roles the complex of parasitoids played in the mortality of the miner were negligible. The mortality ranged from 1.3±0.3 (Perm) to 23.7±3.3% (Tolbazy village).

Parasitoid complex associated with the flea weevil Orchestes alni L. (Coleoptera: Curculionidae) in Bulgaria and a review of host–parasitoid interactions of genus Orchestes Illiger

ABSTRACT Leaves of field elm, Ulmus minor, with mines of Orchestes alni, were collected at four sites in Sofia city during 2018, 2019 and 2023, and kept under laboratory conditions to observe and count emerging parasitoid adults. Results revealed that the parasitoid complex included 22 hymenopteran species belonging to five families: Braconidae (two species), Ichneumonidae (one species) (Ichneumonoidea), Eulophidae (14 species), Eupelmidae (three species) and Pteromalidae (two species) (Chalcidoidea). The most abundant species was Pnigalio agraules (27%), followed by Minotetrastichus platanellus (18%) (Eulophidae) and Trichomalus inscitus (Pteromalidae) (14%). Nine host–parasitoid associations are reported as new. Tetrastichus miser is reported from Bulgaria for the first time. These findings are discussed in relation to the known host–parasitoid associations of the genus Orchestes. The identification of the host species, O. alni, was supported by both morphological and molecular methods.

Natural Control of Sugarcane Top Borer Scirpophaga excerptalis Walker (Crambidae: Lepidoptera) by Its Egg Parasitoids

The sugarcane shoot borer (Scirpophaga excerptalis) is an herbivorous insect that primarily infests sugarcane plants, leading to the development of dead heart symptoms. This study aimed to investigate the contribution of egg parasitoids in mitigating the occurrence of dead heart caused by S. excerptalis infestation. The research was conducted in Asembagus and Malang, East Java, Indonesia. The samples collection of shoot borer eggs were done twice in Asembagus, and three times in Malang. The collected eggs were examined to determine the percentage of parasitism, and the emerged parasitoids were identified. The infestation level of shoot borers was evaluated by counting the dead heart symptoms within 5 m2 observation units, comprising 18 and 15 units in Asembagus and Karangploso, respectively. Three species of parasitoids, namely Telenomus sp., Trichogramma chilonis, and Tetrastichus sp., were found to parasitize S. excerptalis eggs. The average parasitism levels by Telenomus sp., T. chilonis, and Tetrastichus sp. were 74% (ranged: 50-100%), 0.6% (ranged: 0-4.4%), and 14.3% (ranged: 0-100%), respectively. Telenomus sp. was the predominant egg parasitoid observed in all observations at both sites. There was an inverse relationship between the mortality of shoot borer eggs by parasitoids and the occurrence of dead heart symptoms. Higher levels of parasitism were associated with reduced dead shoot symptoms. The natural control of S. excerptalis through the complex of egg parasitoids holds a promise for effective management of sugarcane shoot borers and promoting sustainable agriculture.

New braconid parasitoids (Hymenoptera: Braconidae) on bark beetles in Ihtimanska Sredna Gora Mountain, Bulgaria

In 2020, two braconid species (Hymenoptera: Braconidae) were found as parasitoids of bark beetles in Pinus sylvestris plantations in Ihtimanska Sredna Gora Mt. Coeloides bostrichorum Giraud was reared from stem samples attacked by Tomicus piniperda and Tomicus minor in the region of Krushovitsa vill. (State Forestry Enterprise Elin Pelin), and Dendrosoter middendorffi (Ratzeburg) – by Ips acuminatus, Pityophthorus pityographus and Pityogenes bistridentatus in the region of Krushovitsa vill. and Golema Rakovitsa vill. (State Game Enterprise Aramliets). Coeloides bostrichorum caused 7.4% mortality of T. piniperda and T. minor, and Dendrosoter middendorffi – 5.6-12.5% of Ips acuminatus, 5.6% of P. bistridentatus, and 2.8% of I. acuminatus, P. pityographus and P. bistridentatus. In the total braconid parasitoid complex, D. middendorffi was the dominant species with a relative share of 87.5%.

Egg parasitoid complex of the pine processionary moth in NW Italy

ABSTRACT Investigations on the egg parasitoid complex of the pine processionary moth (PPM), Thaumetopoea pityocampa, were performed in 2020-2022 in seven sites located in NW Italy to determine the parasitoid species composition, seasonal emergence, parasitoid species incidence, and parasitism rate. Furthermore, we examined whether the egg batches parameters and the parasitism rate were influenced by altitude and summer temperatures. A sample of 832 egg batches was collected, each batch consisting on average of 206 ± 5.73 eggs. In total, 35,881 egg parasitoids emerged, mainly represented by four primary species, namely Ooencyrtus pityocampae, Baryscapus servadeii, Anastatus bifasciatus and Trichogramma sp.. Parasitism ranged from 4.27% to 24.41% and the most representative species were O. pityocampae (68.38%) in 2020-2021, and Trichogramma sp. (56.50%) in 2021-2022. The altitude of the sites (808-1303 m a.s.l.) had a negative correlation with all the investigated egg batches parameters (e.g. batch length), and with the parasitism rate by A. bifasciatus and B. servadeii, while a positive correlation was found only for O. pityocampae. The number of days with temperatures above 30°C was positively correlated with parasitism rate for A. bifasciatus and O. pityocampae, and negatively for Trichogramma sp., while no correlation was found with B. servadeii. Since the performance and distribution of the natural enemies is highly dependent on climatic conditions, the regulating effect of parasitoids, reducing PPM population needs to be further investigated, to compare the complex of natural enemies across a wider geographic and climatic range.

PARASITIODS (HYMENOPTERA, EULOPHIDAE, BRACONIDAE) AS A MORTALITY FACTOR FOR THE LIME LEAF MINER (<i>PHYLLONORYCTER ISSIKII</i>, LEPIDOPTERA, GRACILLARIIDAE) IN TRANS-URALIA AND WESTERN SIBERIA

The assemblage of hymenopteran parasitoids associated with the invasive lime leaf miner, Phyllonorycter issikii (Lepidoptera, Gracillariidae) developing on the lime (Tilia cordata) was studied in the Kurgan Province (Madvezh’ye Lake), and in the cities of Tobolsk, Omsk, and Novosibirsk during 2018−2019. Twenty-one species of parasitoids of Ph. issikii were recognized: Pteromalus sp. (Pteromalidae), Cirrospilus diallus, Elachertus sp., Hyssopus geniculatus, H. nigritulus, Pnigalio mediterraneus, Pnigalio sp., Sympiesis dolichogaster, S. gordius, S. sericeicornis, Chrysocharis laomedon, Ch. pentheus, Ch. pubicornis, Ch. viridis, Chrysocharis sp., Neochrysocharis formosus, Minotetrastichus frontalis (Eulophidae), Colastes braconius, Apanteles sp., Pholetesor circumscriptus and Cotesia sp., (Braconidae). Chrysocharis viridis has been reported as a parasitoid of lime leaf miner for the first time. The role of the complex of parasitoids in the mortality of the miner is negligible, the mortality rate ranging from 1.9 ± 0.4 (Novosibirsk) to 23.7 ± 3.3% (Omsk).

PARASITOIDS (HYMENOPTERA) OF PHYLLONORYCTER PLATANI (STAUDINGER, 1870) (LEPIDOPTERA, GRACILLARIIDAE)

The review is devoted to the complexes of parasitoids Phyllonorycter platani (Staudinger, 1870) (Lepidoptera, Gracillariidae). Throughout its range, the miner is attacked by 72 species from 7 families of Hymenoptera. In Europe, 62 species have been identified, in North America, the Caucasus, Western and Central Asia - 5, 3, 12 and 1 species, respectively. Complexes of parasitoids Ph . platani in Eurasia are characterized by absence of narrow specialists. Parasitism rates in European populations of miner are low. Analysis of the composition of the complex of parasitoids indicates a possible North American origin of the miner.

Molecular identification of hymenopteran parasitoids and their endosymbionts from agromyzids.

Three polyphagous pest Liriomyza spp. (Diptera: Agromyzidae) have recently invaded Australia and are damaging horticultural crops. Parasitic wasps are recognized as effective natural enemies of leafmining species globally and are expected to become important biocontrol agents in Australia. However, the hymenopteran parasitoid complex of agromyzids in Australia is poorly known and its use hindered due to taxonomic challenges when based on morphological characters. Here, we identified 14 parasitoid species of leafminers based on molecular and morphological data. We linked DNA barcodes (5' end cytochrome c oxidase subunit I (COI) sequences) to five adventive eulophid wasp species (Chrysocharis pubicornis (Zetterstedt), Diglyphus isaea (Walker), Hemiptarsenus varicornis (Girault), Neochrysocharis formosa (Westwood), and Neochrysocharis okazakii Kamijo) and two braconid species (Dacnusa areolaris (Nees) and Opius cinerariae Fischer). We also provide the first DNA barcodes (5' end COI sequences) with linked morphological characters for seven wasp species, with three identified to species level (Closterocerus mirabilis Edwards & La Salle, Trigonogastrella parasitica (Girault), and Zagrammosoma latilineatum Ubaidillah) and four identified to genus (Aprostocetus sp., Asecodes sp., Opius sp. 1, and Opius sp. 2). Phylogenetic analyses suggest C. pubicornis, D. isaea, H. varicornis, and O. cinerariae are likely cryptic species complexes. Neochrysocharis formosa and Aprostocetus sp. specimens were infected with Rickettsia. Five other species (Cl. mirabilis, D. isaea, H. varicornis, Opius sp. 1, and Opius sp. 2) were infected with Wolbachia, while two endosymbionts (Rickettsia and Wolbachia) co-infected N. okazakii. These findings provide background information about the parasitoid fauna expected to help control the leafminers.

Synoptic catalogue of insect parasitoids associated with Lixinae (Coleoptera: Curculionoidea: Curculionidae)

The first host-parasitoid catalogue for Lixinae is presented. This survey is based on literature search (~300 references) and followed by two parts, firstly one of the Lixinae, and secondly one of parasitoids with distinguishing numbers of their Lixine hosts. There are at least 221 species recorded as parasitoids on 108 lixine species. Records on 12 host-parasitoid associations seem to be questable or based on misidentifications. Most common hosts are species of two genera: Lixus (112 parasitoid species) and Larinus (43). All actually known parasitoids of Lixinae are dipterans (belonging to three families) and hymenopterans (15 families). The latter listed as parasitoids of no less than 102 lixine species (94.4%) and 22 hosts (19.4%) associated with Diptera. Six lixine species associated with dipterans only. Most common parasitoids are braconids. Four parasitoid species have the most extensive list of the hosts: Exeristes roborator (at least 29 host species), Cerceris tuberculata (12), Bracon urinator (11) and Zeuxia cinerea (10). Parasitoid complex of some hosts can include more than 10 (to 44!) species. Information contained in catalogue will be helpful for programs of effective biological control of economic important pests and weeds.

A peculiar case of parasitisation with two new species of wasps parasitizing the rice leaf-roller Pelopidas mathias (Fabricius, 1798) (Lepidoptera: Hesperiidae) from southern India.

Paddy, Oryza sativa L. (Poales: Poaecea) is infested by a series of lepidopteran, coleopteran, hemipteran, and acarine pests in India. Of the long list, the species Rice Leaf-Roller Pelopidas mathias (Fabricius, 1798) (Lepidoptera: Hesperiidae) is one of most encountered defoliators on paddy. Here we record and describe with illustrations, a new parasitic complex comprising of two new species of parasitic wasps, viz. Brachymeria eastwoodi Binoy, sp. nov. and Sympiesis eastwoodi James & Santhosh, sp. nov. on the pupae of P. mathias from southern India. The parasitoid complexes on P. mathias are also augmented.

Exploratory Survey of Lixus algirus L. (Coleoptera: Curculionidae) and Its Natural Enemies in Morocco.

Simple SummaryFaba bean (Vicia faba L.) is one of the most important food legumes, and it is grown in Morocco under rainfed conditions. This crop is cultivated for use in both human food and animal feed and has a high protein content and nutritional value. The faba bean stem borer (Lixus algirus L.) is considered to be one of the major biotic stresses of faba beans in some Mediterranean areas, including Morocco. The aim of this study was to determine the distribution and abundance of L. algirus and its natural enemies in several Moroccan faba bean-growing regions. Among all the regions surveyed in this study, the Gharb and Saïs regions recorded the highest levels of damage by L. algirus. The conducted field surveys led to the identification of three parasitoids and one predator for possible use as biocontrol agents, among which the ectoparasitoid Chlorocytus lixi was the most dominant species.The stem borer weevil, Lixus algirus L. (Coleoptera: Curculionidae), causes severe damage to faba beans (Vicia faba L.) in Morocco. A survey was conducted to determine the distribution of L. algirus, its natural enemies, and the severity of damage it causes to faba beans in Morocco. A total of 16 and 27 stops were randomly selected and surveyed in the major faba bean-growing regions during the years 2017 and 2018, respectively. The Gharb region recorded the highest level of L. algirus infestation at 80% and 71.42% in 2017 and 2018, respectively, followed by the Saïs region at 58.75% and 36% in 2017 and 2018, respectively. Two egg parasitoids (Chlorocytus lixi and Anaphes longicornis), one egg predator (Orius sp.), and a larval parasitoid (Cyanopterobracon) were identified. The ectoparasitoid C. lixi was observed to be the most dominant species, with percentages of parasitism in the regions ranging between 35.75% and 70.49%. The larval parasitoid Cyanopterobracon was the second most abundant species, with percentages of parasitism ranging between 3.03% to 15.96%. Understanding the parasitoid complex of L. algirus in Morocco is necessary for the subsequent development of a biological control program.

Back to the Wild: The Parasitoid Community of Lobesia botrana (Lepidoptera: Tortricidae) in a Grapevine-Free Natural Environment.

Simple SummaryIn a framework of sustainable agriculture, strategies aimed at preserving and enhancing pest natural enemies are crucial. However, knowledge about the parasitoid complex associated with a particular pest is often fragmentary. Herein, we investigated the parasitoids associated with the European grapevine moth, one of the main vine pests in the Mediterranean area, in a natural context, where the moth lives on Daphne gnidium, deemed as its original host plant. We observed a heterogeneous and complex community, consisting of a few predominant parasitoid species, followed by satellite species, and occasional parasitoids. Parasitic wasps, such as Campoplex capitator and Trichogramma spp., can be also found in the vineyards, thus understanding their dynamics in the wild could be useful to improve biological control strategies for managing EGVM populations.The European grapevine moth (EGVM), Lobesia botrana (Lepidoptera: Tortricidae), is one of the major concerns for vineyard managers in the Mediterranean area. It is a polyphagous moth, which develops on a wide variety of host plants, among which the spurge flax, Daphne gnidium (Thymelaeaceae), very likely represents its originary wild host plant. In this study, we investigated the parasitoid complex of L. botrana feeding on D. gnidium during a three-year sampling in a natural reserve in Tuscany, Italy, where this plant is extremely abundant while the grapevine is absent. A total of 24 species of parasitoids were obtained from eggs, larvae, and pupae of EGVM, belonging to 6 families of Hymenoptera and a family of Diptera. The ichneumonid wasp Campoplex capitator was the most abundant larval parasitoid. Four species of the genus Trichogramma were obtained from parasitized eggs during the first year of sampling, with a peak in the parasitisation during the EGVM 3rd generation. Some of the main EGVM parasitoids on spurge flax were also observed in vineyards, although a certain degree of redundancy was observed in the wild, due to several less frequent “satellite” species exploiting the same host. Overall, this research sheds light on the parasitoid community and dynamics of this important moth pest in a grapevine-free natural ecosystem, discussing the possible role of natural areas as ecological reservoirs of pest natural enemies.

Changes in the Parasitism Rate and Parasitoid Community Structure of the Horse Chestnut Leafminer, Cameraria ohridella (Lepidoptera: Gracillariidae), in the Czech Republic

The horse chestnut leafminer, Cameraria ohridella, Deschka and Dimić, is a moth that has invaded most of Europe since it was first recorded in Macedonia near Lake Ohrid in 1985. It attacks horse chestnut trees and causes aesthetic and vitality problems. The parasitism rate, other mortality rates, and parasitoid structure were studied during a five-year survey at six sites in the Czech Republic. The results showed that the total parasitism rates varied from 1.9% to 20.5%, with an average of 7.2%, similar to other those published studies. The parasitism rate was significantly related to year, the developmental stage of C. ohridella, latitude, and greenery maintenance but not to C. ohridella population density, altitude, or area size. In contrast, the total other mortality rates varied from 13.7% to 59.5%, with an average of 31%, but overall temporal changes in the values indicated a declining trend. The parasitoid complex was predominantly polyphagous parasitoids of the family Eulophidae, similar to that found previously in south-eastern Europe. The results further revealed that the most abundant parasitoid species, Minotetrastichus frontalis (Nees), was gradually replaced by Pediobius saulius (Walker). The increasing abundance of P. saulius is thus an interesting adaptation of an autochthonous parasitoid to a new host.

Seasonal Variations of Spodoptera frugiperda Host Plant Diversity and Parasitoid Complex in Southern and Central Benin.

Simple SummaryThe detection of fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) in 2016 attacking maize fields in central and west Africa indicated the need to increase the knowledge on the pest host plants and natural enemies adapting to it. A field survey was conducted for two years (from June 2018 to January 2020) to determine host plant and parasitoid records variations across seasons (maize growing and off-seasons) in selected sites in southern and central Benin. A total of eleven new host plant species were reported for the first time, including grasses. The survey revealed seven parasitoid species belonging to four families, namely Platygastridae, Braconidae, Ichneumonidae and Tachinidae, associated with FAW on maize and alternative host plants. The most abundant parasitoid species found was the egg parasitoid Telenomus remus (Nixon) (Hymenoptera: Platygastridae). The study provides crucial information for understanding the bioecology of the pest and for its long-term management using natural enemies.Fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) was recorded for the first time in 2016 attacking maize fields in central and west Africa. Soon after, several other regions and countries have reported the pest in almost the entire sub-Saharan Africa. In the present study, we assumed that (i) a variety of alternative plant species host FAW, especially during maize off-season, (ii) a wide range of local parasitoids have adapted to FAW and (iii) parasitoid species composition and abundance vary across seasons. During a two-year survey (from June 2018 to January 2020), parasitoids and alternative host plants were identified from maize and vegetable production sites, along streams and lowlands, on garbage dumps and old maize fields in southern and partly in the central part of Benin during both maize growing- and off-season. A total of eleven new host plant species were reported for the first time, including Cymbopogon citratus (de Candolle) Stapf (cultivated lemon grass), Bulbostylis coleotricha (A. Richard) Clarke and Pennisetum macrourum von Trinius (wild). The survey revealed seven parasitoid species belonging to four families, namely Platygastridae, Braconidae, Ichneumonidae, and Tachinidae associated with FAW on maize and alternative host plants. The most abundant parasitoid species across seasons was the egg parasitoid Telenomus remus (Nixon) (Hymenoptera: Platygastridae). These findings demonstrate FAW capability to be active during the maize off-season in the selected agro-ecologies and provide baseline information for classical and augmentative biocontrol efforts.

Naturalized Dolichogenidea gelechiidivoris complement the resident parasitoid complex of Tuta absoluta in North‐eastern Spain

AbstractOur work reports on the establishment of the neotropical parasitoid Dolichogenidea gelechiidivoris Marsh (Hymenoptera: Braconidae) for the first time in Europe. This larval parasitoid has been recorded in samples collected in commercial tomato crops in Catalonia (North‐eastern Spain) from 2016 to the present. Dolichogenidea gelechiidivoris is considered to be a new biocontrol agent among the resident parasitoid complex of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

Natural Enemies and Pest Control in Field-Grown Crop in Southern Senegal

Crop pests are a permanent threat to horticultural production. Several control methods are recommended for their control, including biological control. This method based on the use of natural enemies is not well established. The objective of this study was to assess the diversity and abundance of natural enemies of crop pests. A survey of crops associated with pests was carried out on 144 fields in southern Senegal to measure the diversity and abundance of natural enemies of various crop pests, determine the native parasitoid complex and assess parasitism rates. Ecological indices were calculated to assess the diversity of natural enemies. A total of 25 natural enemy species were identified, including 15 parasitoids and 10 predators. Predatory Hemiptera and Parasitoid Hymenoptera were high biodiversity. The parasitism rates vary between 0 and 50% depending on the abundance of pests and parasitoid species. Knowledge of the diversity of natural enemies and the understanding of trophic interactions with pests are important in the development of biological crop protection in order to preserve resilience in agroecosystems.

The parasitoid complex of diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), in Canada: impact and status

Abstract Diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), a globally important pest of Brassicaceae crops, migrates into all provinces of Canada annually. Life tables were used to determine the mortality levels contributed by the parasitoid complexes associated with diamondback moth in British Columbia, Ontario, Prince Edward Island, and insular Newfoundland. Overall, diamondback moth populations showed high generational mortality (> 90%) in all provinces, although parasitism levels were generally low. The net reproductive rate of increase in diamondback moth was less than 1.0 (populations declined) in both years in British Columbia and in each of two years in Newfoundland and Ontario, but it was greater than 1.0 in all three years in Prince Edward Island. Lower parasitism levels were found in Prince Edward Island (3.0–6.3%) compared with other provinces (8.4–17.6%, except one year in British Columbia). Diadegma insulare was the main larval parasitoid found; it was present in all provinces. Microplitis plutellae was present in all provinces except British Columbia. Oomyzus sokolowskii was found in British Columbia and Ontario. The parasitoid community documented from sentinel sampling was less diverse than that found through destructive sampling. Hypotheses are provided to explain the presence of major parasitoids. Increasing larval parasitism would have the largest effect on diamondback moth population growth in Canada.

Abundance and impact of egg parasitoids on the pine processionary moth (Thaumetopoea pityocampa) in Bulgaria

We collected 2297 egg batches of the pine processionary moth (Thaumetopoea pityocampa) during the period 1991-2018 from 44 sites in Bulgaria. The sampling sites were classified into three groups according to T. pityocampa phenological form (early, late and both forms) as well as in two groups of its range (historical and newly colonized areas). Seven primary egg parasitoids were identified: Ooencyrtus pityocampae, Baryscapus servadeii, Pediobius bruchicida, Anastatus bifasciatus, Eupelmus (Macroneura) vesicularis, Eupelmus (Macroneura) vladimiri and Trichogramma sp., and one hyperparasitoid, Baryscapus transversalis. The average impact of egg parasitoids (the percentage of parasitized host eggs) on T. pityocampa in Bulgaria was 13.8%. The two main parasitoids, O. pityocampae and B. servadeii, parasitized about 90% of the host eggs. The remaining parasitoids were of insignificant consequence to the parasitism of the T. pityocampa eggs, but in areas recently colonized by the pest, A. bifasciatus and Trichogramma sp. had a noticeable share (up to 33% of the impact). In old habitats of the host (areas colonized more than 10 years), the impact was almost two times higher than in new ones (15.3% vs. 8.6%). This could be attributed to B. servadeii, which was rare in newly colonized areas of T. pityocampa (impact 0.5%), but strongly dominant in old habitats (impact 7.2%). In contrast, O. pityocampae had a significant impact in new habitats (4.9%), which increased only slightly over time, reaching 6.0% in old habitats. There was no significant difference between the percentage of parasitism of the early and late form of the pine processionary moth (14.8% vs. 15.9%). However, there was a significant difference in the share of separate species in the parasitoid complex: in the early form, B. servadeii definitely dominated (63% of the infested eggs), while in the late form O. pityocampae dominated, although not so strongly (52% of the infested eggs). This difference is most likely due to the phenological characteristics of the parasitoids and the two forms of T. pityocampa. B. transversalis secondarily infested about 5% of the eggs of O. pityocampae and B. servadeii. This percentage was slightly lower for new habitats and habitats of the early form of pine processionary moth (3% and 4%, respectively). The impacts of the main parasitoids O. pityocampae and B. servadeii as well as the total impact of the parasitoid complex as a whole decreased with altitude. Conversely, the impacts of A. bifasciatus and Trichogramma sp. slightly increased with altitude probably due to the reduced competition of the main parasitoids.

Biology, parasitoid complex and potential distribution of saxaul's dominant defoliators, Teia dubia (Lepidoptera: Lymantriidae).

Natural enemies that impact pest populations must be understood in order to build integrated pest control strategies and to understand the most important aspects affecting pest dynamics. Haloxylon ammodendron (C. A. Mey.) Bunge is an important perennial plant species extensively used in sand stabilization and wind prevention in arid areas. This study aimed to determine the main defoliators that damage H. ammodendron and the parasitoid complex associated with them. Twelve species of defoliators were found in Northern Xinjiang, and Teia dubia (Tauscher) (Lepidoptera: Lymantriidae), Scrobipalpa sp. (Lepidoptera: Gelechiidae), and Eucharia festiva Hüfnagel (Lepidoptera: Arctiidae) were the dominant pests. T. dubia is the predominant defoliator with three generations a year. Northwest China, Central Asia, and the Mediterranean region are potentially suitable habitats for T. dubia in the world, while Xinjiang is the primary distribution area in China. Parasitoids belonging to seven species and four families were reared from the larvae of T. dubia, they were all endoparasitoids and koinobiont. Cotesia sp. (Hymenoptera: Braconidae) is the dominant parasitoid and prefer to parasitic in the 3rd-5th instar larvae. The present study provides the basis for understanding the species composition and natural enemies of lepidopteran defoliators. It will be an effective tool for the integrated pest management programs of H. ammodendron forest.