The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
J C Van Lenteren - One of the best experts on this subject based on the ideXlab platform.
-
the parasite host relationship between Encarsia Formosa gah hymenoptera aphelinidae and trialeurodes vaporariorum westw homoptera aleyrodidae
Journal of Applied Entomology, 2009Co-Authors: J C Van LenterenAbstract:A search was made in California (USA) for alternative parasites able to control the greenhouse whitefly T. vaporariorum (Westw.) on tomatoes in greenhouses with a low temperature regime. The preselection of candidate species for biological control by means of laboratory methods is discussed. Four aphelinid species (Encarsia Formosa Gahan, E. pergandiella Howard, E. sp. near meritoria Gahan and Eretmocerus sp.) could be reared and a laboratory method was developed to test their parasitization efficiency at 17 ± 1°C constant temperature: the reproductive capacity of the four species was measured over a period of 20 days. The possible consequences of the different reproductive strategies of these last two species for their use as biological control agents are discussed. No definite answer to the question which of these two species would be most suitable for whitefly control under low temperature conditions could be given, therefore greenhouse experiments have been initiated in the Netherlands and the U.K. Zusammenfassung Uber die Parasit-Wirt-Beziehungen zwischen Encarsia Formosa Gab. (Hym. Aphelinidae) und Trialeurodes vaporariorum (Westw.) (Hom., Aleyrodidae). X. Vergleich von 3 Encarsia spp. und 1 Eretmocerus sp. hinsichtlich ihrer Fahigkeit, die Mottenschildlaus an Tomaten in Gewachshausern mit relativ niedriger Temperatur in Schach zu halten Weil die steigenden Energiepreise die Zuchter dazu antreiben, ihre Produkte, insbesondere Tomaten, im Gewachshaus bei niedrigen Temperaturen zu ziehen, wird auch die biologische Schadlingsbekampfung dazu gezwungen, naturliche Feinde anzuwenden, die imstande sind, auch unter diesen neuen Umstanden die Schadlinge, im vorliegenden Fall die Weise Fliege, Trialeurodes vaporariorum, zu bekampfen. Bisher wurde die Schlupfwespe Encarsia Formosa zur Bekampfung eingesetzt, aber ihre Leistung wird bei niedrigen Temperaturen schnell schlechter. Deshalb wurde in Kalifornien nach alternativen Parasiten gesucht, die fahig sein konnten, auch unter diesen Umstanden die Weise Fliege befriedigend niederzuhalten. Die Auswahl von geeigneten Parasitenarten mit Hilfe von Labormethoden wird diskutiert. Es zeigte sich, das 4 Aphelinidenarten: Encarsia Formosa Gahan, E. pergandiella Howard, E. sp. nahe meritoria Gahan und Eretmocerus sp., gezuchtet werden konnten. Eine Labormethode zur Prufung des Parasitierungserfolges dieser Arten bei 17 ± 1dC wurde entwickelt. Die Fortpflanzungskapazitat der 4 Arten wurde wahrend einer Periode von 20 Tagen gemessen. Die Ergebnisse zeigen, das E. sp. nahe meritoria und Eretmocerus sp. weniger aussichtsreich sind als die anderen beiden Arten, die erste, weil ihre Fekunditat niedrig ist und die zweite, weil ihre Entwicklung bei 17°C zu lange dauert. Die thelytoke Art E. Formosa zeigte eine hohe Fekunditat, aber ihre Entwicklung war signifikant langsamer als die der arrhenotoken Art E. pergandiella. Die moglichen Konsequenzen der verschiedenen Fortpflanzungsstrategien der letzten 2 Arten fur ihre Anwendung als biologische Bekampfungsmittel werden diskutiert. Die Frage, welche dieser Arten am besten zur Bekampfung der Weisen Fliege bei niedrigen Temperaturen eingesetzt werden konnte, konnte nicht eindeutig beantwortet werden. Neue Experimente in Gewachshausern in den Niederlanden und im Vereinigten Konigreich wurden begonnen, die diese Frage klaren sollen.
-
The parasite‐host relationship between Encarsia Formosa Gah. (Hymenoptera: Aphelinidae) and Trialeurodes vaporariorum (Westw.) (Homoptera: Aleyrodidae)
Journal of Applied Entomology, 2009Co-Authors: J C Van LenterenAbstract:A search was made in California (USA) for alternative parasites able to control the greenhouse whitefly T. vaporariorum (Westw.) on tomatoes in greenhouses with a low temperature regime. The preselection of candidate species for biological control by means of laboratory methods is discussed. Four aphelinid species (Encarsia Formosa Gahan, E. pergandiella Howard, E. sp. near meritoria Gahan and Eretmocerus sp.) could be reared and a laboratory method was developed to test their parasitization efficiency at 17 ± 1°C constant temperature: the reproductive capacity of the four species was measured over a period of 20 days. The possible consequences of the different reproductive strategies of these last two species for their use as biological control agents are discussed. No definite answer to the question which of these two species would be most suitable for whitefly control under low temperature conditions could be given, therefore greenhouse experiments have been initiated in the Netherlands and the U.K. Zusammenfassung Uber die Parasit-Wirt-Beziehungen zwischen Encarsia Formosa Gab. (Hym. Aphelinidae) und Trialeurodes vaporariorum (Westw.) (Hom., Aleyrodidae). X. Vergleich von 3 Encarsia spp. und 1 Eretmocerus sp. hinsichtlich ihrer Fahigkeit, die Mottenschildlaus an Tomaten in Gewachshausern mit relativ niedriger Temperatur in Schach zu halten Weil die steigenden Energiepreise die Zuchter dazu antreiben, ihre Produkte, insbesondere Tomaten, im Gewachshaus bei niedrigen Temperaturen zu ziehen, wird auch die biologische Schadlingsbekampfung dazu gezwungen, naturliche Feinde anzuwenden, die imstande sind, auch unter diesen neuen Umstanden die Schadlinge, im vorliegenden Fall die Weise Fliege, Trialeurodes vaporariorum, zu bekampfen. Bisher wurde die Schlupfwespe Encarsia Formosa zur Bekampfung eingesetzt, aber ihre Leistung wird bei niedrigen Temperaturen schnell schlechter. Deshalb wurde in Kalifornien nach alternativen Parasiten gesucht, die fahig sein konnten, auch unter diesen Umstanden die Weise Fliege befriedigend niederzuhalten. Die Auswahl von geeigneten Parasitenarten mit Hilfe von Labormethoden wird diskutiert. Es zeigte sich, das 4 Aphelinidenarten: Encarsia Formosa Gahan, E. pergandiella Howard, E. sp. nahe meritoria Gahan und Eretmocerus sp., gezuchtet werden konnten. Eine Labormethode zur Prufung des Parasitierungserfolges dieser Arten bei 17 ± 1dC wurde entwickelt. Die Fortpflanzungskapazitat der 4 Arten wurde wahrend einer Periode von 20 Tagen gemessen. Die Ergebnisse zeigen, das E. sp. nahe meritoria und Eretmocerus sp. weniger aussichtsreich sind als die anderen beiden Arten, die erste, weil ihre Fekunditat niedrig ist und die zweite, weil ihre Entwicklung bei 17°C zu lange dauert. Die thelytoke Art E. Formosa zeigte eine hohe Fekunditat, aber ihre Entwicklung war signifikant langsamer als die der arrhenotoken Art E. pergandiella. Die moglichen Konsequenzen der verschiedenen Fortpflanzungsstrategien der letzten 2 Arten fur ihre Anwendung als biologische Bekampfungsmittel werden diskutiert. Die Frage, welche dieser Arten am besten zur Bekampfung der Weisen Fliege bei niedrigen Temperaturen eingesetzt werden konnte, konnte nicht eindeutig beantwortet werden. Neue Experimente in Gewachshausern in den Niederlanden und im Vereinigten Konigreich wurden begonnen, die diese Frage klaren sollen.
-
the parasite host relationship between Encarsia Formosa hym aphelinidae and trialeurodes vaporariorum hom aleyrodidae
Journal of Applied Entomology, 2009Co-Authors: Mariek Eggenkamprotteveel H Mansveld, J C Van Lenteren, J M Ellenbroek, J WoetsAbstract:Zusammenfassung Zur Parasit-Wirt-Beziehung zwischen Encarsia Formosa (Hym., Aphelinidae) und Trialeurodes vaporariorum (Hom., Aleyrodidae). XII. Populationsdynamik des Parasiten und des Wirtes in einem grosen Gewachshaus, unduberprufung der in den Niederlandenublichen Aussetzungsmethoden des Parasiten Die weise Fliege, Trialeurodes vaporariorum (Westwood), ist ein Grosschadling an verschiedenen Gewachshauskulturen. Seit etwa 1970 wird dieser Schadling auf wachsender Flache und in immer mehr Landern durch Einsatz eines naturlichen Feindes, der Schlupfwespe Encarsia Formosa Gahan bekampft. 1979 wurde dieses biologische Verfahren in 11 Landern auf ungefahr 1200 ha durchgefuhrt. Einige Jahre nach Beginn der Anwendung von E. Formosa begannen wir eine Forschungsarbeituber den Massenwechsel des Parasiten und seines Wirtes, mit folgenden Zielsetzungen: 1 Entwicklung einer schnellen und zuverlassigen Zahlmethode fur Gartner sowie Lieferanten der Schlupfwespen. 2 Bewertung der in den Niederlandenublichen Methode des Schlupfwespeneinsatzes. 3 Erklarung der gewohnlich unbefriedigenden Erfolge in kleineren Gewachshausern im Vergleich zu Groseinheiten. 4 Bewertung der Hypothese von Huffaker (1958), wonach die Co-Existenz von Beutetier und Jager nur moglich ware, wenn bestimmte Bedingungen bezuglich raumlicher Verteilung und Wanderfahigkeit von beiden gegeben sind. Der Massenwechsel und die Verteilung der Weisen Fliege und ihres Parasiten wurde 16 Wochen lang in einem 6480 qm grosen Gewachshaus mit 18 000 Tomatenpflanzen verfolgt. Dabei wurden 2 Verfahren verglichen: die wochentliche Zahlung der Puppen an allen befallenen Pflanzen, und eine geschichtete Stichprobe mit wochentlicher Kontrolle an 0,5% der Pflanzen. Da das letztere Verfahren die wirklichen Zahlen und Verteilungen der beiden Insekten nicht erfaste, darf es den Praktikern nicht empfohlen werden (Eggenkamp-Rotteveel Mansveld et al. 1978). Die Zahlungen und die daraus konstruierten Verteilungsmuster ermoglichten folgende Schlusfolgerungen: 1 Das in den Niederlandenubliche Einsatzschema war erfolgreich. Angefangen wird dabei 1 bis 4 Wochen nach dem ersten Auftreten des Schadlings; insgesamt werden im allgemeinen 6 Schlupfwespen pro Pflanze eingesetzt, verteiltuber 4 Freilassungen in 14tagigem Abstand; in unserem Fall waren es jedoch insgesamt 9,8 Schlupfwespen. Die (schwankende) Zahl der Weisen Fliegen blieb sehr gering unduberschritt niemals 0,1 Puppe pro Pflanze. Bis zum Ende der Kultur wurde kein von der Weisen Fliege verursachter Schaden beobachtet. Ein solcher Erfolg ist keine experimentelle Ausnahme, sondern durchaus in der Praxis erzielbar. 2 Sowohl die Weisen Fliegen als auch die Schlupfwespen zeigten eine ausgepragte Herdbildung. Die Herde veranderten sich allmahlich zu einem regelmasigen Verteilungsmuster in der letzten Woche. Dies wurde ausgelost von den wandernden Imagines der Weisen Fliege. Dadurch wuchs die Zahl der besiedelten Pflanzen; weil aber zugleich die Zahl der Puppen pro besiedelte Pflanze abnahm, stieg die Gesamtzahl der Weisen Fliegen nicht an. 3 Die aktive Verbreitung und die Suchfahigkeit der Schlupfwespen ist ausgezeichnet. Das einzelne Insektuberfliegt Abstande von mindestens 10 Metern. Sogar vereinzelte Puppen des Wirtes innerhalb von Gruppen sonst unbesiedelter Pflanzen wurden aufgefunden. 4 Bei Huffakers (1958) Versuchen wurden Subpopulationen einer phytophagen Milbe manchmal vollstandig von einer rauberischen Milbe vernichtet, wahrend zu gleicher Zeit neue Subpopulationen des Phytophagen an anderen Fruchten hochkamen. Die Herde in unserem Versuch (Herd = Gruppe von Weisen Fliegen und/oder Schlupfwespen, die durch unbesiedelte Pflanzen wenigstens 3 m von anderen Gruppen getrennt ist) wurden nie ganzlich beseitigt. Innerhalb eines Herdes aber verschwand eine Subpopulation an einer Pflanze manchmal durch vollstandigen Parasitismus, wahrend sich an einer anderen Pflanze eine neue Subpopulation entwickelte. Von Herden oder Pflanzen, an denen alle Puppen parasitiert sind, wandern die Schlupfwespen ab und suchen sich neue Subpopulationen der Weisen Fliege. Dadurch schwankte die Parasitierungsrate pro Pflanze zwischen 0 und 100%, doch blieb die durchschnittliche Rate recht konstant (etwa 50%). Obwohl die Ereignisse an einzelnen Pflanzen sich also oft drastisch voneinander unterschieden, addierten die lokalen Unterschiede sich zu einer stabilen Lage im gesamten Gewachshaus.
-
amitus fuscipennis an alternative to the biological control of trialeurodes vaporariorum by Encarsia Formosa
Bulletin of Insectology, 2008Co-Authors: J C Van LenterenAbstract:Biological control of Trialeurodes vaporariorum (Homoptera Aleyrodidae) by Amitus fuscipennis (Hymenoptera Platygastridae) with or without Encarsia Formosa (Hymenoptera Aphelinidae) was tested in both a glasshouse and a plastic greenhouse during two consecutive production cycles of a beef tomato crop on the Bogota Plateau in Colombia. The mean temperature was around 16 °C in the plastic greenhouse and around 17 °C in the glasshouse. A. fuscipennis was introduced at a rate of 5 pupae per m2 per week during the first 13 weeks of the first cycle. During the second cycle, 2.5 pupae of both E. Formosa and A. fuscipennis per m2 per week were introduced during the first 13 weeks. During the first cycle, control was obtained for 5 months in the plastic greenhouse and 3 months in the glasshouse, after which the population of T. vaporariorum adults increased to a maximum of 50 adults per plant. Parasitism was initially higher than 80% but then decreased to 56% in the plastic greenhouse and to 20% in the glasshouse. During the second cycle, biological control was successful in both greenhouses. Populations of T. vaporariorum were lower than 1.2 adults per plant and parasitism, caused mainly by E. Formosa, was near 90% most of the time. Therefore, E. Formosa is recommended to keep populations of T. vaporariorum at low levels in unheated greenhouses on the Bogota Plateau. When high populations of T. vaporariorum are to be expected or control of high-density spots is required, A. fuscipennis could be a beneficial addition to E. Formosa.
-
Temporal and spatial analysis of greenhouse whitefly and its parasitoid Encarsia Formosa in two types of greenhouse ecosystems
Journal of Applied Entomology, 1999Co-Authors: N. Jiang, J C Van Lenteren, R.m. Xu, H J W Van RoermundAbstract:Temporal and spatial relationships between greenhouse whitefly and its parasitoid Encarsia Formosa were analysed at different levels by using Rook's neighbourhood model, and for two types of greenhouses: a small greenhouse in China (15.1 m 2 ) and a large greenhouse in the Netherlands (6480 m 2 ). For whitefly eggs and larvae, there was no difference in their spatial relationship occurring within- and between-plot in the two types of greenhouses. Eggs and larvae occurrence aggregated with no special directional distributions. Whitefly adults exhibited nonlinear spatial density dependence within-plot, and moved randomly between-plot. Whitefly adults preferred to fly away in a N-S directions and to settle down at a NW-SE directions with an increase in the number of their neighbouring infected plants within-plot. The parasitoid E. Formosa showed a strong relationship with the temporal and spatial distribution of the host, but influenced the spatial distribution of whitefly.
P A Brennan - One of the best experts on this subject based on the ideXlab platform.
-
parasitism of the castor whitefly trialeurodes ricini homoptera aleyrodidae by Encarsia Formosa hymenoptera aphelinidae bionomics in relation to temperature
Bulletin of Entomological Research, 1996Co-Authors: Parviz Shishehbor, P A BrennanAbstract:Selected life history characteristics of Encarsia Formosa Gahan parasitizing the castor whitefly, Trialeurodes ricini (Misra) were studied at three constant temperatures (20, 25 and 30°C). Egg-to-adult developmental time decreased from 32 days at 20°C to 13 days at 30°C. An average of 241 day-degrees was required to complete development above the lower threshold temperature (12°C). Juvenile mortality was 34, 40 and 47% at 20, 25 and 30°C, respectively. Mean longevity of E. Formosa ranged from 7.7 days at 20°C, to 2.6 days at 30°C. Mean total fecundity ranged from 18 to 36 eggs/female. Intrinsic rate of increase (r m ) increased with temperature from 0.065/day at 20°C to 0.169/day at 30°C. Generation times decreased from 37 to 14.5 days with increasing temperature.
-
functional response of Encarsia Formosa gahan parasitizing castor whitefly trialeurodes ricini misra hom aleyrodidae
Journal of Applied Entomology, 1996Co-Authors: Parviz Shishehbor, P A BrennanAbstract:: Laboratory experiments were conducted to measure the functional response of Encarsia Formosa parasitizing castor whitefly, Trialeurodes ricini. Parasitoids were isolated singly for 24 h in 10 cm Petri dishes with either 4, 8, 16, 32, 64 or 128 prepupal stages of T. ricini. Results showed a typical Type II response, with up to 12 prey attacked when 128 were provided. The rate of attack and handling time were 1.43 and 0.077 (days), respectively. Theoretically, one T. ricini prepupa could be parasitized by E. Formosa every 111–115 minutes (0.077–0.080 days), and an adult E. Formosa could parasitize a maximum of 13 castor whitefly prepupae per day.
Martha S Hunter - One of the best experts on this subject based on the ideXlab platform.
-
heterospecific ovicide influences the outcome of competition between two endoparasitoids Encarsia Formosa and Encarsia luteola
Ecological Entomology, 2007Co-Authors: Timothy R Collier, Martha S Hunter, Suzanne E KellyAbstract:1. Studies of inter-specific competition in parasitoids have largely focused on the outcome of within-host competition and the behavioural mechanisms by which female parasitoids prevent competition. Another, less well studied, possibility is oviposition preceded by ‘heterospecific ovicide’, the destruction of the other species’ egg. Heterospecific ovicide essentially eliminates within-host competition. 2. This study investigated the mechanisms and outcome of within-host competition in Encarsia Formosa and Encarsia luteola, solitary endoparasitoids of whitefly pests. These species are known to commit ovicide of conspecific eggs. 3. Competition experiments indicated that the offspring of second-ovipositing females had an apparent advantage in competition, regardless of whether the second female was E. Formosa or E. luteola. 4. Observations of ovipositor movement through the cuticle of host whitefly nymphs showed that both species often committed heterospecific ovicide and then oviposited or host-fed. Multiparasitism and heterospecific host discrimination were less common and absent respectively. 5. Heterospecific ovicide appears to explain the second-female advantage in competition between these species. Second-female advantage is contrary to the paradigmatic view of multiparasitism, where the first-ovipositing female has an advantage in competition or one of the species consistently prevails in competition.
-
developmental rates of two congeneric parasitoids Encarsia Formosa and e pergandiella hymenoptera aphelinidae utilizing different egg provisioning strategies
Journal of Insect Physiology, 2002Co-Authors: David M Donnell, Martha S HunterAbstract:Endoparasitic Hymenoptera vary in the extent to which they provision their eggs and thus in the degree to which they appear to rely on their hosts for resources during embryonic development. In this study, developmental rates were examined in two congeneric parasitoid species, Encarsia Formosa and E. pergandiella, that provision their eggs to different degrees. E. Formosa eggs are much larger than E. pergandiella eggs. E. Formosa eggs hatch significantly earlier than the eggs of E. pergandiella when deposited in 1st or 4th instar nymphs of a common whitefly host, Bemisia tabaci. Both species hatch earlier in 4th instar nymphs, but the delay in hatching in hosts parasitized as 1st instars is much greater in E. pergandiella. While E. Formosa develops more rapidly to the 1st larval instar, E. pergandiella emerge as adults significantly earlier, though smaller, than E. Formosa adults regardless of the host instar parasitized. These findings show that the extent of provisioning in the eggs of these wasps does not strictly determine their order of progression through different stages of development. 2002 Published by Elsevier Science Ltd.
-
egg size intrinsic competition and lethal interference in the parasitoids Encarsia pergandiella and Encarsia Formosa
Biological Control, 2002Co-Authors: Timothy R Collier, Suzanne E Kelly, Martha S HunterAbstract:Abstract Recent population dynamic theory predicts that disruption of biological control may occur when one parasitoid species' superiority in intrinsic competition is associated with a lower ability to find and exploit hosts (i.e., ability in extrinsic competition). One might expect such a trade-off, for instance, if parasitoids with larger (and fewer) eggs are more likely to prevail in intrinsic competition than species with smaller (and more numerous) eggs. We tested the idea that relative egg size could be used to predict the outcome of intrinsic competition in two closely related endoparasitoids, Encarsia pergandiella Howard and Encarsia Formosa Gahan. Contrary to expectation, the parasitoid species with smaller eggs, E. pergandiella, prevailed in intrinsic competition, regardless of the order that hosts were exposed to the two species. In a literature survey, we found four studies of competing pairs of endoparasitoid species for which: (a) egg size estimates were available and (b) one species was consistently superior in intrinsic competition. In three of the four studies, the small-egged species prevailed in intrinsic competition, as we also found. Although E. Formosa lost in intrinsic competition, this species negatively affected E. pergandiella's progeny production by host feeding on and killing hosts containing E. pergandiella eggs. E. Formosa females also host fed on conspecific-parasitized hosts. As a mechanism of both intra- and interspecific interference competition, host feeding on parasitized hosts contradicts assumptions about the nature of interference competition in existing population dynamics models.
-
ovicide in the whitefly parasitoid Encarsia Formosa
Animal Behaviour, 2000Co-Authors: Jessa F Netting, Martha S HunterAbstract:The oviposition decisions made by insect parasitoids when encountering hosts of variable quality have been the subject of extensive theoretical and experimental investigation. For parasitoids that lay their eggs inside the host, the possible outcomes of encounters with parasitized hosts have been assumed to include only oviposition (superparasitism), rejection, or in some cases feeding on host haemolymph. We document another outcome in Encarsia Formosa Gahan (Hymenoptera: Aphelinidae), a species that has been a model system for the study of oviposition behaviour. In E. Formosa, females may kill eggs previously laid within the host by jabbing them with their ovipositor before ovipositing themselves. (1) Our observations indicated that jabbed eggs were indeed killed. (2) In experimental arenas in the laboratory, ovicide occurred in the majority of encounters with parasitized hosts and at highest frequency in encounters resulting in oviposition. (3) There was no significant difference in the handling time associated with oviposition+ovicide in parasitized hosts in comparison with oviposition alone, suggesting that there is no time cost to ovicide. (4) Ovicide did not appear to be incidental to normal probing within a host. Radial analysis of the direction of ovipositor movement with respect to the centre of the previously laid egg within the host showed that females engaged in ovicidal bouts probed most often in the direction of the egg. This is the first well-documented study of ovicide in an endoparasitoid. We suggest ovicide may be under-reported in other endoparasitoid species due to the difficulty of observing it. 2000 The Association for the Study of Animal Behaviour
Eustachio Tarasco - One of the best experts on this subject based on the ideXlab platform.
-
effects of entomopathogenic fungi on Encarsia Formosa gahan hymenoptera aphelinidae activity and behavior
Biological Control, 2016Co-Authors: Monica Oreste, Giovanni Bubici, Michele Poliseno, Eustachio TarascoAbstract:Abstract The effects of a previously selected entomopathogenic fungus, Beauveria bassiana AL1 strain, and the B. bassiana-based mycoinsecticide Naturalis were evaluated on the Trialeurodes vaporariorum-Encarsia Formosa system. The parasitoid’s ability to recognize uninfected and infected hosts was examined by evaluation of E. Formosa tropism in ‘choice’ conditions and its activity (residence time on leaf, searching time, handling hosts time and hosts acceptance) in no-choice conditions. Finally, the role of E. Formosa in transmitting the mycoses from infected to uninfected host populations was estimated. E. Formosa showed no differential tropism in ‘choice’ conditions. It was able neither to locate the host at distance nor to discriminate between infected and uninfected hosts. E. Formosa was able to vector fungal propagules from contaminated to uncontaminated hosts during its activity. The results of these laboratory experiments have clarified some biological and behavioral aspects of pathogen-host-parasitoid interactions.
-
effect of beauveria bassiana and metarhizium anisopliae on the trialeurodes vaporariorum Encarsia Formosa system
Journal of Pest Science, 2016Co-Authors: Monica Oreste, Giovanni Bubici, Michele Poliseno, Eustachio TarascoAbstract:The virulence of three strains of Beauveria bassiana and one of Metarhizium anisopliae was tested against Trialeurodes vaporariorum and its parasitoid Encarsia Formosa in laboratory assays. These strains were previously selected for their virulence against Galleria mellonella and Tenebrio molitor. The commercial B. bassiana strain ATCC 74040, both as pure fungal culture and formulated myco-insecticide (Naturalis), was included in the assays as positive control. First, the entomopathogenic fungal strains were tested for their virulence against T. vaporariorum nymphs on tomato leaf disks. Then, the E. Formosa development was evaluated under treatment with the entomopathogenic fungal strains at five different time points from the parasitization of T. vaporariorum nymphs. The virulence of our entomopathogenic fungal strains was superior to that of ATCC 74040, although not significantly, resulting in a cumulative mortality (CM) of T. vaporariorum nymphs 7 days after inoculation (DAI) greater than 86 %. Our M. anisopliae strain CIST8 was the most effective (96.6 % CM 7 DAI), even superior to the myco-insecticide Naturalis (94.2 %), which was more effective than the ATCC 74040 pure strain (85.6 %). The entomopathogenic fungal strains, and especially Naturalis, negatively affected E. Formosa development and its parasitization activity of T. vaporariorum nymphs. This effect was more pronounced when the fungal strains were applied before parasitization. Results suggest that the application of entomopathogenic fungi is incompatible with E. Formosa release on crops.
Parviz Shishehbor - One of the best experts on this subject based on the ideXlab platform.
-
Intraguild predation by the generalist predator Orius majusculus on the parasitoid Encarsia Formosa
BioControl, 2013Co-Authors: Fariba Sohrabi, Parviz Shishehbor, Annie Enkegaard, Moosa Saber, Mohammad Said MosaddeghAbstract:Intraguild predation of Orius majusculus (Reuter) (Heteroptera: Anthocoridae) on Encarsia Formosa (Gahan) (Hymenoptera: Aphelinidae), both natural enemies of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), was studied under laboratory conditions. The experiments quantified prey consumption by 5th instar nymphs and adults of O. majusculus offered unparasitised 3rd, early 4th or 4th instar B. tabaci nymphs or parasitised nymphs containing 2nd or 3rd larval instar or pupal parasitoids. In addition, prey preference of the two stages of O. majusculus for parasitised or unparasitised whitefly nymphs was studied using nine different prey combinations. Both predator stages readily preyed upon on both unparasitised and parasitised B. tabaci . In no-choice experiments, predation on 3rd instar E. Formosa by adult predators was the highest, while predator nymphs preyed most on unparasitised 3rd instar B. tabaci and 2nd instar parasitoids. Predation of predator stages was lowest on 4th instar B. tabaci and E. Formosa pupae. In all prey combinations, both stages of O. majusculus showed a significant preference for parasitised over unparasitised whitefly nymphs except for the combination of 5th instars of O. majusculus with early 4th instar whiteflies and E. Formosa pupae. The results indicate that intraguild interactions between O. majusculus and E. Formosa may have negative effects on biological control of B. tabaci .
-
parasitism of the castor whitefly trialeurodes ricini homoptera aleyrodidae by Encarsia Formosa hymenoptera aphelinidae bionomics in relation to temperature
Bulletin of Entomological Research, 1996Co-Authors: Parviz Shishehbor, P A BrennanAbstract:Selected life history characteristics of Encarsia Formosa Gahan parasitizing the castor whitefly, Trialeurodes ricini (Misra) were studied at three constant temperatures (20, 25 and 30°C). Egg-to-adult developmental time decreased from 32 days at 20°C to 13 days at 30°C. An average of 241 day-degrees was required to complete development above the lower threshold temperature (12°C). Juvenile mortality was 34, 40 and 47% at 20, 25 and 30°C, respectively. Mean longevity of E. Formosa ranged from 7.7 days at 20°C, to 2.6 days at 30°C. Mean total fecundity ranged from 18 to 36 eggs/female. Intrinsic rate of increase (r m ) increased with temperature from 0.065/day at 20°C to 0.169/day at 30°C. Generation times decreased from 37 to 14.5 days with increasing temperature.
-
functional response of Encarsia Formosa gahan parasitizing castor whitefly trialeurodes ricini misra hom aleyrodidae
Journal of Applied Entomology, 1996Co-Authors: Parviz Shishehbor, P A BrennanAbstract:: Laboratory experiments were conducted to measure the functional response of Encarsia Formosa parasitizing castor whitefly, Trialeurodes ricini. Parasitoids were isolated singly for 24 h in 10 cm Petri dishes with either 4, 8, 16, 32, 64 or 128 prepupal stages of T. ricini. Results showed a typical Type II response, with up to 12 prey attacked when 128 were provided. The rate of attack and handling time were 1.43 and 0.077 (days), respectively. Theoretically, one T. ricini prepupa could be parasitized by E. Formosa every 111–115 minutes (0.077–0.080 days), and an adult E. Formosa could parasitize a maximum of 13 castor whitefly prepupae per day.