The systematic position of the genusTainania [Hym.: Chalcididae]

A comparative study of the genusTainania Masi and the genusAntrocephalus Kirby revealed that the former genus does not have sufflcient good morphological characteristics to hold the status of a separate genus from that of the genusAntrocephalus. The important morphological characterstics of the genusAntrocephalus have been given.

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Résumé La comparaison du genreTainania Masi et du genreAntrocephalus Kirby montre que le premier n'a pas de caractères morphologiques assez bons pour justifier d'être distingué du second. Les caractères morphologiques importants du genreAntrocephalus sont rappelés.

     

Indian species of the genusProspaltella Ashmead [Hym.: Aphelinidae]

An account is given of five Indian species of the genusProspaltella Ashmead. Four new species (P. breviclavata sp. n.,P. flava sp. n.,P. indica sp. n. andP. udaipuriensis sp. n.) are described. A key to Indian species ofProspaltella is also given.

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Résumé Des données sont fournies sur cinq espèces indiennes du genreProspaltella. Quatre nouvelles espèces (P. breviclavata, P. flava, P. indica etP. udaipuriensis) sont décrites. Une clé systématique des espèces deProspaltella de l'Inde est proposée.

     

A new species ofEncarsia [Hym.: Aphelinidae] parasitizingBemisia tabaci[Hom.: Aleyrodidae]

Encarsia deserti n.sp., a parasite ofBemisia tabaci Gennadius is described. It resemblesE. formosa Gahan, but has a light brown head and thorax, is smaller, and is biparental. This species was found in Southern California and Arizona parasitizingB. tabaci and was introduced into Israel for the control of this pest.     

Searching and ovipositional behavior ofAmitus hesperidum [Hym.: Platygasteridae] andEncarsia opulenta [Hym.: Aphelinidae] parasitoids of the citrus blackfly [Hom.: Aleyrodidae]

Searching behavior ofAmitus hesperidum Silvestri andEncarsia opulenta (Silvestri) for immatureAleurocanthus woglumi Ashby was similar. Both parasitoids moved unidirectionally until they encountered a host aggregation at which time they changed to a pattern of short walks with numerous turns. Parasitoid ovipositor insertion was generally at midbody between the host sternites and tergites.Amitus hesperidum females showed a significant preference for 1st instar hosts, have an ovipositional marker, do not feed on exudates from ovipositional wounds (host feed), and have significantly shorter ovipositional times and adult life spans thanE. opulenta which showed a significant preference for 2nd instar hosts, lack an ovipositional marker, and host feed.Encarsia opulenta females showed a significant preference for hosts previously parasitized byA. hesperidum but the reverse was not true. The average number of hosts parasitized by females of both parasitoid species was uninfluenced by the previous presence of the other parasitoid species on the same leaf.     

Importance de la nutrition chezAphelinus sp. [Hym.Aphelinidae]

Résumé L'incidence de la nutrition sur la biologie des Aphélinides est étudiéc et analysée sous ses différents aspects: maturation sexuelle, spécificité parasitaire (adaptation à un nouvel h?te) et longévité. Les faits observés sont rapprochés de certains phénomènes d'adaptation à des facteurs du milieu connus chez d'autres groupes d'insectes. D'importants travaux ont été effectués sur un Aphélinide monophage,Aphelinus mali Haldeman depuis son introduction en Europe en 1929 pour freiner les pullulations du puceron lanigèreEriosoma lanigerum Hausm. Ce n'est que depuis une quinzaine d'années que les chercheurs américains ont orienté leurs recherches vers un autre Aphélinide,Aphelinus asychis Walker (=semiflavus Howard), susceptible d'attaquer un grand nombre d'espèces d'Aphides-h?tes. Cependant, la polyphagie de ce parasite fut très peu étudiée et c'est seulement en 1970 queRaney etal.,Manglitz & Schalk déterminant la fécondité du parasite en présence de divers h?tes, ont observé des différences de fécondité qui les ont conduits à considérer que certains h?tes étaient préférés par le parasite.

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Summary A study of polyphagous Aphelinids, parasites of aphids, revealed the existence of host conditioning. The physiology and behaviour of the female is influenced by the aphid species on which it feeds: sexual maturation, fecundity (measured by number of aphids mummified by one female) and longevity are impaired when this species differs from the one from which the female hatched. When females are fed with honey and water, longevity decreases (is reduced by about 15 days). Nutritive elements accumulated during larval life are used and eggs are progressively resorbed. This condition is not irreversible: if such females are reared with aphids, mature eggs can be observed after two days. Fecundity and longevity are decreased when one female (Aphelinus asychis), hatched from an aphid species A, is reared on an aphid species B. In the F₂ generation, the parasite is better adapted to the new host; in F₃ fecundity may be comparable with that recorded in females reared on aphid host A. However, if F₃ females hatched from species B mummies are now placed on aphid host A, the same kind of biological disturbances are observed as in the original transfer (A to B). After disproving the hypothesis of genetical selection of individuals adapted to the new host, the influence of nutrition on female physiology is demonstrated. This conditioning may be compared with that inAcrididae, attributable to a density factor, or that inNemeritis andDrosophila, to the odour of certain chemicals.

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Le présent article est extrait de la thèse de Doctorat d'état soutenue le 20 mars 1972 à l'Université Paris VI.     

Establishment of the imported parasiteProspaltella perniciosi [Hym.: Aphelinidae] onQuadraspidiotus perniciosus [Hom.: Diaspididae] in Greece

Prospaltella perniciosi Tower was imported in Greece to aid in the biological control ofQuadraspidiotus perniciosus Comstock. Two to 10 years following release in apple trees the parasite was found well established onQ. perniciosus with low parasitism exceed to 2–5%. Parasitism by indigenous natural enemies, mostlyAphytis spp., was also low. Considering that these trees also suffer damage by other major pests, in order to obtain full benefit from the biological control ofQ. perniciosus compatible methods of supressing these pests are required.

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Résumé Prospaltella perniciosi Tower fut importé en Grèce pour la lutte biologique contreQuadraspidiotus perniciosus Comstock. Deux à 10 ans après son lacher dans des vergers de pommier, le parasite est trouvé bien implanté dans la population de Pou de San José, le taux de parasitisme oscillant entre 2 et 5%. Le parasitisme par des ennemis naturels indigènes, principalement parAphytis spp., était aussi bas. Tenant compte du fait que ces arbres subissent des dégats par d'autres ennemis importants et afin d'obtenir le maximum d'efficacité de la lutte biologique contreQ. perniciosus, des méthodes adéquates pour la répression de cet insecte sont exigées.

     

Eretmocerus Corni Hald. [Hym. Aphelinidae] Parassita delSiphoninus Phillyreae Halid. [Hom. Aleyrodidae]

Summary A serious attack onPirus and some ornamentalRosaceae by the white flySiphoninus phillyreae Halid. was recently recorded in the province of Thessaloniki. About 20 per cent of the white fly population was parasitized byEretmocerus corni Hald. Described from America, the Aphelinid, was not found in Europe up till now.      

Biosystematic and evolutionary statuses of two sympatric populations ofAphytis mytilaspidis [Hym.: Aphelinidae]

Studies on 2 sympatric morphologically identical populations ofAphytis mytilaspidis Le Baron frpm Greece were conducted on their mating behavior, reproductive isolation, hybridization in the laboratory, host preferences and adult survivorships at different temperatures. These studies revealed that the 2 populations were partially reproductively isolated and qualify at least for the rank of strong “semispecies” with respect to one another. Marked differences were also recorded in their host preferences and adult survivorships at different temperatures. Gene flow among these populations in nature is likely to occur only in one direction. Differences in host preference may further reduce gene flow by providing ecological reproductive isolation. Also hybrid sterility is indicated which if complete would prove these 2 forms to be sibling species. Based on the experimental evidence, an hypothesis is presented that these 2 populations represent a case of incipient if not complete sympatric speciation, with the presumed descendant population (R-69-120) possessing a broader host range and better adult longevity, in comparison to the proposed progenitor population (R-63-63-4).     

Egg laying and host stage preference at constant temperatures inEncarsia tricolor [Hym.: Aphelinidae]

Encarsia tricolor Foërster is a facultative autoparasitoid that develops on the important pestTrialeurodes vaporariorum (Westwood) in outdoor crop conditions, which makes this aphelinid species promising for biological control programs in regions where field and protected crops coexist. In this paper we report the results obtained in the study of daily and totalE. tricolor egg laying and of adult female preference for different host stages in which to lay eggs at constant temperatures in the range 10 to 32 °C. Only whitefly nymphs were present in the searching arena (tomato leaflets). The mean number of eggs laid per female in one day ranged from 4.0 (10 °C and 32 °C) to 15.2 (24 °C). The mean total number of eggs increased with temperature from 10 to 28 °C, reaching a maximum of 123 eggs per female at 28 °C, and decreased sharply from 28 to 32 °C. The relation between the intrinsic rate of increase (r_m) and temperature in the range 10 to 28 °C followed a straight line whose equation was r_m=?0.076+0.011*T (R²=0.99). The r_m ofE. tricolor was greater than the r_m ofT. vaporariorum when temperature was higher than 9.2 °C. The preference for any particular host instar in which to lay eggs was not always significant. However, N4 was the host instar preferred whenever preference was statistically significant.     

Use of the parasiteEncarsia formosa [Hym.: Aphelinidae] as a part of pestmanagement on cucumbers

Experiments using the parasiteEncarsia formosa Gahan to controlTrialeurodes vaporariorum (Westwood) on commercially grown cucumbers are described. Encarsia formosa was introduced by the dribble method or at different rates whenT. vaporariorium infestation was detected. It is concluded that an initial number of 10–30 adultT. vaporariorum per 100 plants require 3 parasite introductions at a rate of 5 parasites per plant, while less than 1 adultT. vaporariorum per 100 plants requires a rate of 3 parasites per plant in each introduction. The use ofE. formosa could not be integrated with diazinon or lindane drenches againstThrips tabaci Lindem., but was successfully integrated with triforine spray against mildew infestations.     

Temperatures lethal for citrus blackfly parasites,Encarsia opulenta andE. Smithi [Hym.: Aphelinidae]

Seasonally acclimatized adult and immature parasites of the citrus blackfly (CBF),Aleurocanthus woglumi Ashby, were exposed to high or low temperature extremes for 3 h periods. Death of all summer adults ofEncarsia opulenta Silvestri andE. smithi Silvestri occurred between 35° and 40°C. Within CBF hosts,E. opulenta were not able to emerge when temperatures reached between 45° and 50°C. In winter experiments adults of bothEncarsia species succumbed between −5° and −10°C. In a comparison of the 2 seasonal tests, a higher percentage ofE. smithi adults were able to survive both higher and lower temperatures thanE. opulenta, but the main interspecific difference was the ability ofE. opulenta within CBF to survive −10° to − 15°C whileE. smithi did not. Limited data forAmitus hesperidum Silvestri [Hym.: Platygasteridae] indicated that the immatures survived better at low, and not as well at high, temperatures as either species ofEncarsia. Florida Agricultural Experiment Station Journal Series # 5549.     

Aphytis riyadhi n. sp. [Hym.: Aphelinidae], a parasite ofAonidiella spp. [Hom.: Diaspididae]

A new species ofAphytis reared fromAonidiella orientalis collected from citrus in Saudi Arabia is described and compared morphologically with four other closely relatedAphytis species.

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Résumé Aphytis riyahdi n. sp., parasite deAonidiella orientalis (Newst.) en Arabie Saoudite a été importé en Californie pour procéder à des lachers contreAonidiella aurantii (Maskell) afin d'améliorer la lutte biologique contre cette cochenille dans une zone de vaste superficie et de climats variés.

     

The biology ofAphelinus flavus [Hym. Aphelinidae], a parasite of the Sycamore aphidDrepanosiphum platanoides [Hemipt. Aphididae]

Aphelinus flavus Thompson is a solitary internal parasite. Males and females overwinter as free living adults and appear on sycamore in mid, May. The female consumes aphid body fluids and kills 1 aphid for food for every 1.7 eggs deposited, and parasitises 48 aphids over 27 days. Development from egg to adult requires and parasitises 48 aphids over 27 days. Development from egg to adult requires 57 days. The mortality of parasites while within the nummified host was determined: it was related to hyperparasitism and predation. Mortality due to mummies being brushed off the leaves was also determined.     

Competitive displacement betweenAphytis spp. [Hym. Aphelinidae] parasites of the California red scale in cyprus

In Cyprus,Aphytis chrysomphali (Mercet) andAphytis melinus DeBach are the only significant parasites of the California red scale,Aonidiella aurantii (Maskell).A. chrysomphali, presumably native, has been virtually displaced byA. melinus from the interior dry areas of the island after the importation of the latter in 1961. Presently the former parasite dominates only in some of the coastal areas with a mild and rather humid climate.Aphytis ? coheni DeBach that initially displacedA. chrysomphali in the release areas, was replaced by the latter parasite and was occasionally found in small numbers only in one location. Traces ofAphytis ?lingnanensis Compere were also found in some locations. Two otherAphytis spp., imported from California, were released and recovered but it is too early to determine their permanent establishment and significance.     

Note surProspaltella aurantii How. [Hym., Aphelinidae] parasite deQuadraspidiotus pyri Licht. dans les Alpes-Maritimes [Hom., Diaspidinae]

Summary American species ofProspaltella, P. aurantii How. unknown in Europe was studied in Alpes-Maritimes onQ. pyri living on fig-trees. In this country, host has two annual generations, and it overwinters like a second stage larvae, while in the same time, three generations occur for parasite. In the particular climatic conditions of this study, the efficiency of this parasite is complete before two years owing to the destruction of the male progeny.      

The biology ofLophyroplectus luteator [Hym.: Ichneumonidae] onNeodiprion sertifer [Hym.: Diprionidae] in Ontario

Adult femaleLophyroplectus luteator (Thunb.) oviposit in all feeding stages ofNeodiprion sertifer (Geoff.), although they prefer the smallest of any larvae present at a given time. Females tend to distribute eggs contagiously both within and between host feeding colonies. Eclosion of eggs does not occur until after the host has spun its cocoon. Larval development then requires approximately 1 month in the laboratory. There is an obligatory eonymphal diapause which requires a minimum of 60–80 days at 2°C to fulfil, and post-diapause development requires 3–4 weeks.     

Host discrimination byChelonus insularis [Hym.: Braconidae], telenomus heliothidis [Hym.: Scelionidae], andTrichogramma pretiosum [Hym.: Trichogrammatidae]

The ability of female parasitoids (Chelonus insularis Cresson,Telenomus heliothidis Ashmead, andTrichogramma pretiosum Riley) to distinguish between parasitized and unparasitized tobacco budworm,Heliothis virescens (F.), eggs was determined in laboratory studies. All 3 species were relatively efficient at detecting eggs that were previously parasitized by conspecific females.T. heliothidis andT. pretiosum were able to discriminate on the basis of external examination of host eggs, whereasC. insularis appeared to examine hosts internally as well as externally. In interspecific tests, no species readily rejected eggs parasitized by the other 2 species.     

Competition betweenBracon mellitor [Hym.: Braconidae] andCatolaccus grandis [Hym.: Pteromalidae] for their hostAnthonomus grandis [Col.: Curculionidae]

BioControl - Laboratory studies of competition between populations of 2 parasitoids of the cotton boll weevil,Anthonomus grandis Boheman, showed that populations ofCatolaccus grandis (Burks)...     

Greenhouse whitefly control through the combined use of the colour attraction system with the parasite waspEncarsia formosa [Hym.: Aphelinidae]

The combined use of colour attraction (yellow sticky plates) andEncarsia formosa (Gahan) parasites reduced the greenhouse whiteflyTrialeurodes vaporariorum (Westwood) population in a spring tomato crop to an extremely low level. Whiteflies were strongly attracted to yellow sticky plates while the parasite,E. formosa, was not attracted so long as suitable and sufficient hosts were present. As the numbers of whiteflies declined, parasites were increasingly trapped by the plates. The percent parasitization increased continuously during the experiment, reaching about 90%, indicating the complete compatibility of colour attraction and biological control.     

Effects of winter temperatures on the sex ratios ofAphytis melinus [Hym.: Aphelinidae] in the San Joaquin Valley of California

Laboratory bioassays of overwintering field populations of the California red scale parasitoidAphytis melinus DeBach showed a shift in sex ratio of F₁ progeny after prolonged exposure to winter temperatures in Tulare County, California. In 7 of 8 tests, short-term winter field exposure (<75 days) did not result in a significant male bias in sex ratios of F₁ progeny when compared to sex ratios observed in laboratory cultures maintained at 27°C. Long term exposure (109–139 days), however, resulted in significantly (P<0.05) higher male bias in F₁ sex ratios in 5 of 6 tests. These results from field populations ofA. melinus agree with conclusions of low temperature laboratory tests onAphytis species (lingnanensis, melinus) by other workers. Mention of a proprietary or commercial product in this paper does not constitute an endorsement of this product by the University of California.