Opius Concolor Research Articles

Ground cover management with mixtures of flowering plants to enhance insect pollinators and natural enemies of pests in olive groves

The potential of ground cover management with mixtures of selected plants to provide habitats for pollinating insects and natural enemies of pests in an olive grove in southern Greece, was studied over a period of 3 years (2011–2013). The management consisted of the establishment of 3 m2 patches of sown plant species or spontaneous natural vegetation between trees along tree lines. The sown plant species in the mixtures were Sinapis alba L. (Brassicaceae), Glebionis segetum (L.) Fourr. and Glebionis coronaria (L.) Cass. ex Spach (Asteraceae), Vicia sativa L. and Pisum sativum L. (Fabaceae), Borago officinalis L. (Boraginaceae), Coriandrum sativum L. and Pimpinella anisum L. (Apiaceae). Sowing was performed in autumn or spring and the peak flowering period occurred at the end of March to end of April, and at the end of May to end of June, respectively. Visual estimation of flower cover, counts of pollinator landings on flowers and presence of beneficial arthropods (suction sampling) were performed in three 7–10 day intervals during peak flowering, for each experimental year. Overall, patches with sown plant mixtures attracted higher numbers of pollinating Hymenoptera compared to native vegetation, especially mining bees and honey bees (Apis mellifera) as well as megachilids and bumble bees (Bombus spp.). Sinapis alba, present in both sown and native vegetation patches, attracted mainly mining bees and honey bees. The flowering mixture with C. sativum and B. officinalis was more attractive to honey bees than the one with G. coronaria as main flowering species but they were both equally attractive to mining bees, although the species composition may well have been different. Hymenopterous parasitoids, primarily Braconidae and Chalcidoidea, were sampled from the patches and the olive fruit fly parasitoid Opius concolor (Hymenoptera: Braconidae) was recorded on olive trees adjacent to the flowering patches. Large numbers of predators, namely Orius sp. (Hemiptera: Miridae) and lacewings (Neuroptera: Chrysopidae), were recorded in the patches, principally in those with the mixture containing mostly S. alba. Our results suggest that ground cover in patches with suitable flowering species could be part of a sustainable olive crop management system, providing food and refuge for pollinating insects and beneficial arthropods.

Status, Distribution and Parasitism Rate of Olive Fruit Fly (Bactrocera oleae.Rossi) Natural Enemies in Lebanon

Olive tree is considered one of the most important cultivated crops in Lebanon. The cultivated area is mainly concentrated in the north and south Lebanon. Among the obstacles affecting olive cultivation is the olive fruit fly infestation which negatively alters the quality of olive oil. Olive fruit fly (Bactrocera oleae) is mainly controlled by chemical means. At the present time, no biological program against this pest is considered in Lebanon. The aim of this study is to investigate the status of olive fruit fly parasites in Lebanon. The study was conducted for one year in 28 orchards located in five regions of olive production. Fruit samples were collected weekly from June to October. A total of 23096 fruits was collected from all orchards. Eight parasites were detected. Eupelmus urozonous and Opius concolor were the most abundant parasites in most orchards, the others were restricted to specific locations. The only exception was observed at Abdeh site where most of the parasites were isolated. Parasitism rates ranged from 2.4 to 42.1 % and the average rate of all locations was 13.3%. The low parasitism rate recorded in this study is insufficient to control olive fruit fly. Introduction and rearing of natural enemies along with other management tactics may enhance the control of olive fruit fly infestation

Studies on the parasitoid Opius concolor Sźepligeti (Hymenoptera: Braconidae), associated with zizyphus fruit fly, Carpomyia incompleta Becker (Diptera: Tephritidae)

The present study aims to show that zizyphus trees must be preserved from exposure to pesticide applications for several reasons: they are trees with no economic values and are the sole host plant of zizyphus fruit fly (ZFF), Carpomyia incompleta, (monophagous species) add to that the pest (ZFF) is very sensitive to the associated parasitoid, Opius concolor. Therefore, the present experiment was carried out for two successive years, 2011 and 2012. In the first season of 2011, ZFF started to emerge at the first of April with 28% emergence, thereafter the fly emergence gradually increased to reach the maximal value (56%) by the end of May. In the second season of the same year, the percentage of flies emergence started with 63.67% during 11 September, afterwards it increased to reach the maximal value (83.67%) by the end of September. Data also indicated that the overall males/females ratio of ZFF was 0.43 during both the years of study. The maximum parasitism was recorded in 22 April (26.0%), meanwhile no individual parasitoid was observed during September. The fluctuation of ZFF in both the years showed similar trend. The ratio between the parasitoid O. concolor and ZFF in 2011 was similar to that of 2012 except that a low percentage of parasitism was observed at the beginning of September. Keeping in view the aim of the present investigation, as well as the obtained results, zizyphus tree from our point of view may become a host plant with highly economic importance where it acts as a natural resource or reservoir for one of the most effective parasitoid of fruit fly species without any economical cost. We also advise those working in the field of Horticulture, Pomology Departments to propagate and cultivate zizyphus trees around fruit orchards to act as windbreaks besides their function as a source of parasite.

Laboratory Effects of Ingestion of Azadirachtin by Two Pests ( Ceratitis capitata and Spodoptera exigua ) and Three Natural Enemies ( Chrysoperla carnea , Opius concolor and Podisus maculiventris )

The effects of azadirachtin on two pests: neonate larvae and newly emerged adults of Ceratitis capitata (Wiedemann) and last instar larvae of Spodoptera exigua (Hubner); and three natural enemies: newly emerged adults of Opius concolor Szepligeti, second instar larvae of Chrysoperla carnea (Stephens), and fifth instar nymphs of Podisus maculiventris (Say) were studied in laboratory. Adult insects were exposed to a non-oil formulation of azadirachtin (Align, emulsifiable concentrate, 3.2% azadirachtin, Sipcam Inagra, Spain) via their drinking water and immature instars were reared in the presence of the insecticide-treated diet. The natural enemies were exposed to at least the maximum field recommended concentration of the insecticide (0.15% v/v). Azadirachtin was highly toxic to neonate larvae of C. capitata and prevented adult emergence at a concentration of 1 mg a.i. l -1 . When adults were fed the insecticide at the maximum recommended concentration, their survival was not affected but egg laying was totally inhibited. Last instar S. exigua larvae were also very susceptible (LC 50 = 7.7 mg a.i. l -1 ) and at a concentration of 10 mg a.i. l -1 fecundity of surviving adults, and egg fertility, were reduced by 72 and 85%, respectively. Effects on O. concolor were large, and significant reductions in longevity, percentage of attacked hosts, and progeny size per female, were recorded. The predator P. maculiventris was much less sensitive to azadirachtin, but slight reductions in survival of emerged adults and of reproductive parameters occurred. The insecticide had no significant effect on C. carnea larvae fed with treated Sitotroga cerealella (Oliver) eggs, probably because of its inability to penetrate inside the egg.

Insecticidal Activity of Strains of Bacillus thuringiensis on Larvae and Adults of Bactrocera oleae Gmelin (Dipt. Tephritidae)

The olive fly, Bactrocera oleae, is the key pest on olives in the Mediterranean area. The pest can destroy, in some cases, up to 70% of the olive production. Its control relies mainly on chemical treatments, sometimes applied by aircraft over vast areas, with their subsequent ecological and toxicological side effects. Bacillus thuringiensis is a spore-forming soil bacterium which produces a protein crystal toxic to some insects, including the orders of Lepidoptera, Diptera, and Coleoptera and other invertebrates. The aim of this study was to search for isolates toxic to B. oleae. Several hundred B. thuringiensis isolates were obtained from olive groves and olive presses in different areas of Greece, Sardinia (Italy), and Spain and from cooperating scientists throughout the world. Some isolates were found toxic only to adults or larvae and some to both stages of the olive fly. In addition, the most toxic isolates were assayed on Opius concolor Szepl. (Hym. Braconidae), the most important parasitoid of the olive fruit fly. Only 3 isolates out of 14 gave significant mortality against this parasitoid. Several of the most toxic crystalliferous isolates may contain novel toxins since they gave no PCR products when probed with primers specified for 39 known toxin genes.

LEARNING BEHAVIOUR OF OPIUS CONCOLOR SZLEPLIGETI (HYMENOPTERA: BRACONIDAE) IN HOST DISCRIMINATION

Abstract Laboratory experiment on learning behaviour of Opius concolor in host discrimination was conducted. The superparasitism by both the “inexperienced” and “experienced” wasps at the highest ratio of parasitoid: host (1: 0. 9) was significantly higher than those at two low ratios (1: 5 and 1: 10). The distributions of the eggs of O. concolor females in hosts examined by dissection showed that the eggs laid by both “inexperienced” and “experienced females” at 1: 0. 9 ratio did not agree with the Poisson distribution. However, at 1: 5 ratfio the eggs laid by “experienced” ones did not agree with Poisson distribution, whereas by inexperienced ones agreed with Poisson distribution. On the contrary. the eggs laid both by “inexperienced” and “experienced” wasps at 1: 10 ratio agreed with the Poisson distribution. The results of experiment on the self‐superparasitism indicated that both “experienced” and “inexperienced” single females, in 6 h at ratio 1: 5, could carry out on superparasitization.

Argan (Sapotaceae) Trees as Reservoirs for Mediterranean Fruit Fly (Diptera: Tephritidae) in Morocco

Argan, Argania spinosa L. (Sapotaceae), forests cover a700,000 ha in the Souss region of Morocco and are known as an enormous potential reservoir of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) for nearby citrus orchards. We studied C. capitata population dynamics in a cattle- and insecticide-free domain from 1987 to 1990. Autumnal argan fruiting in 1986 and 1989 highly modified population dynamics by increasing the number of generations breeding in argan. Thus, up to 4 generations can breed in argan, whereas only 2 develop in spring fruiting alone. Most argans contained only a single oviposition. Oviposition was observed with autumnal fruiting from December to late June, just before the last fruit fell. Larval development began in argans still on trees and continued on fallen fruit. Numbers of eggs, larvae per fruit, and adult males captured per Procida trap increased from late May to June or July. Heterogeneity of argan tree phenology permits huge C. capitata populations with a large spread in adult emergences. Each argan produced on average 3 ± 1.3 adult flies. The proportion of aborted ovipositions was high, as was pupal mortality. Only 1 species of endoparasite, Opius concolor Szepligetti, emerged from argans. Parasitism remains constant from March to July but was too low to curb the enormous fly population increase.

New insight into the antennal chemosensory function of opius concolor (hymenoptera, Braconidae)

The presence of taste and olfactory chemosensilla is demonstrated by using both morphological and electrophysiological techniques on antennae of Opius concolor, a parasitoid of tephritid larvae. Observation under the Scanning Electron Microscope revealed the presence of large sensilla trichodea with an apical pore, and of flat plates (sensilla placodea) extending almost the entire length of each antennomere. By means of currently used electrophysiological techniques, it was possible to record both the gustatory activity generated by sensilla trichodea following contact with KC1 100 mM and sucrose 100 mM solutions, and olfactory activity probably generated by sensilla placodea in response to volatile stimuli. The analysis of gustatory activity showed that each sensillum trichodeum consisted of at least three chemosensory units. This supports the assumption that in O. concolor single sensilla may, by providing different spike discharge patterns, which depend on the quality and intensity of the stimulus, provide the CNS with adequate information for peripheral discrimination among stimulating chemicals. Study of the sensory input of O. concolor with electrophysiological techniques may be of great scientific importance for possible applications in biocontrol of the olive fly.

Vitesse de développement d’Opius concolor (Hym.: Braconidae): à différentes températures constantes

Opius concolor Szepligeti is a parasite ofBactrocera oleae (Gmelin) and other Tephritid flies. Its development rate was studied with the Sharpe-DeMichele mathematical model, modified by Schoofieldet al. (1981), using the S.A.S. program elaborated by Wagneret al. (1984). This program chose a four parameter poikilotherm model with high temperatures inhibition. Duration of parasitoid development at seven constant temperatures ranged from 14.6±1.7 days at 28°C (males), to 77.2±5.5 days at 15°C (females). Male development was consistently found to be shorter than that of females. Low development threshold and degree-days needed to complete total development were determined with the “Regression Line” and “Thermal Summation” methods. Values (cumulated for both sexes) were found to be respectively 11.7°C and 11.8°C (low threshold), 255.9 and 251.9±16.8 days (thermal constant). Considerations on the possibility of establishingOpius concolor in northern and central Italian regions are discussed.

Virus-like particules in the poison glant of the parasitic wasp Opius concolor.

SummaryVirus‐like particles (VLP's) have been found in the poison glands of adult females of the parasitic wasp Opius concolor Szèpl. (Hymenoptera, Braconidae). These VLP's are found in the secretory cells either free in the cytoplasm or within cytoplasmic vesicles, sometimes associated to a secretory apparatus.Negative staining of these VLP's has revealed the occurrence of two different particles. The first type exhibits icosahedral symmetry (diameter around 70nm) and hollow surface spikes, this morphology being typical of the genus Cypovirus (Reoviridae). The other type is pleomorphic and presents an envelope with clubshaped projections (diameter ranging from 30 to 60nm), as classical textbook examples of Coronaviruses, but smaller. Function and full characterisation of these particles are not yet known.

Cyromazine Effects on Opius concolor SZEPL. (Hymenoptera: Braconidae) Applied through Laboratory Host Ceratitis capitata WIED. (Diptera: Tephritidae)

The effects of topical treatments with five concentrations (0.00001 mg/ml, 0.01 mg/ml, 0.1 mg/ml, 1 mg/ml and 10 mg/ml) of cyromazine on Ceratitis capitata WIED. (Dip., Tephritidae) and indirect effects of these treatments on a larval parasitoid, Opius concolor SZEPL. (Hym., Braconidae), were studied. The results obtained showed that topical treatments on the third larval stadium of C. capitata did not affect the development. Further, at the concentrations used here, cyromazine did not affect the development or parasitism of O. concolor.

Analysis of a laboratory method to test the effects of pesticides on adult females ofOpius concolor(Hym., Braconidae), a parasitoid of the olive fruit fly,Bactrocera oleae(Dip., Tephritidae)

The laboratory test described in the present paper assesses pesticide effects on the ‘most exposed’ life stage of the parasitic wasp Opius concolor, and it has been developed and interpreted according to the guidelines of the IOBC/WPRS Working Group ‘Pesticides and Beneficial Organisms ‘. The evaluation of results is based on longevity and parasitism of adult females exposed to afresh residue of pesticide on a glass surface. Longevity measurements were based on the time of exposure required to cause 50% mortality (LT50) and were compared to a standard control LT50 in order to calculate the reduction caused by the pesticide. Parasitism was surveyed by means of three sequential determinations: the number of days that females were seen parasitizing, the mean number of attacked hosts and the progeny size per female. These determinations were also compared to a control to calculate the impact of pesticides. Using this ‘worst case’ situation, pesticides reducing the beneficial capacity of O. concolor below the ...

Frequency of Dacus oleae (Gmelin) immature stages and their parasites in seven olive varieties in Jordan

The study showed three generations of the olive fruit fly from June to November 1984. Eggs were first detected in the Shami variety in early June. There were three peaks of eggs found in almost all varieties in late June, late August and late October. Highest number of larvae was found in Santa in July, and Ascolano and Kheli in August. There were no significant differences in the number of larvae per 100 infested fruits between all varieties during the first generation except Nabali. Pupae inside the fruits first appeared in Shami in July. The number of pupae inside the fruits was high in all varieties in August. Holes made by larvae falling to the soil for pupation were recorded in early August in all varieties, except Nabali where they appeared in late August and early September. During the second generation the highest number of larvae was found in Ascolano, Santa and Rase’e varieties. The recorded parasites were Opius concolor, Eupolmus urozonus, Tetrastichus sp., Trichostereresis glabra, and Lasioglassum sp. The most abundant parasites were O. concolor and Tetrastichus sp.

Parasitoids for the control of Dacus oleae in Crete1

In spite of widespread application of poisonous bait sprays against Dacus oleae in Crete, populations of its parasites sometimes show high densities. Most important are the chalcid ectoparasites Eupelmus urozonus and Pnigalio mediterraneus and the braconid Opius concolor. Several efforts for biological control of D. oleae with O. concolor have been made in Greece. The most promising were inundative releases against the spring generation of D. oleae as well as releases within foci of D. oleae in summer. Introduced exotic parasitoids (Biosteres longicaudatus, Dirhinus giffardii and B. oophilus) failed to establish.

The influence of female age and host size on the sex ratio of the parasitoid Opius concolor

AbstractThe sex ratio of the progeny of single females parasitizing large hosts favoured the females (sex ratio — 0.26); but on small hosts favoured the males (0.73). No differences in mortality of the sexes were detected. The sex ratio was independent of female age when large hosts were used. The percentage of males observed in the progeny of the first day of female oviposition was significantly greater than the mean, irrespective of the age at which female oviposition began. When females were exposed to small hosts, a greater percentage of females was observed in the progeny from the last days of oviposition.RÉSUMÉInfluence de l'âge de la femelle et de la taille de l'hôte sur le taux sexuel du parasitoïde Opius concolorL'influence de la taille de l'hôte et de l'âge de la femelle sur le taux sexuel de la descendance a été étudiée sur le parasitoïde Opius concolor Szépl.Le taux sexuel de la descendance des femelles isolées est favorable aux femelles (t.s. = 0,26) quand elles ont à leur disposition des hôtes de grande taille, tandis qu'avec des hôtes petits le taux sexuel est favorable aux mâles (t.s. = 0,73). On n'a pas détecté de mortalité différentielle des sexes.Les pourcentage de mâles obtenu le premier jour de ponte des femelles sur les hôtes de grande taille est significativement différent de la moyenne, indépendamment de l'âge de la femelle à ce moment. Cependant, sur des hôtes petits, bien que restant favorable aux mâles dans l'ensemble, une plus grande proportion de femelles à partir des premiers jours de ponte a pu être observée.