RearingTrichogramma nubilale [Hymenoptera: Trichogrammatidae] on eggs of the tobacco hornworm,Manduca sexta [Lepidoptera: Sphingidae]

The fresh frozen egg of the tobacco hornworm (TBH)Manduca sexta (L.), is an efficient and superior host for mass production ofTrichogramma nubilale Ertle & Davis. Each host egg may produce 10.7±2.8 (n=7) large, robust, and activeT. nubilale. The proportion of ♀♀ stabilized at 80–90% with 69.9±26.6 (n=8) ovarian eggs per female. As many as 3 ♀♀ were observed ovipositing simultaneously into a single TBH egg. Superparasitism (>10 progeny) should be avoided because it may cause nutritional or space limitations on the development of effectiveT. nubilale.      

The scale response ofTrichogramma [Hymenoptera: Trichogrammatidae]: Variation among species in host specificity and the effect of conditioning

Host specificity and the effect of conditioning on a behavioral response to lepidopteran scales varied among the females of 4Trichogramma spp. observed in laboratory experiments.Trichogramma species nrPretiosum Riley andT. exiguum Pinto & Platner responded weakly toOstrinia nubilalis (Hübner) scales relative toHeliothis zea (Boddie) andManduca sexta (L.).T. maltbyi Nagaraja & Nagarkatti andT. minutum Riley did not discriminate between scales from these 3 hosts. Conditioning with various combinations of host scales and eggs did not alter host specificity, but in some cases, changed general responsiveness to scales. These were attributed to habituation, loss of appetitive drive due to long oviposition bouts, and associative learning. In general, the scale response seems to be innate and fairly nonspecific.      

Sensory receptors of the ovipositor ofTrichogramma maidis [Hym.:Trichogrammatidae]

Sensory receptors of the ovipositor ofTrichogramma maidis are described. Sense organs are found on the 2^nd valvifers (1 type), on the tip of the 3^rd valvulae (2 types) and on the 1^st valvulae (4 types). The nature and possible functions of these sensilla are discussed.      

Parasitism in diversified agroecosystems: Phenology ofTrichogramma minutum [Hymenoptera: Trichogrammatidae]

Parasitism ofOstrinia nubilalis egg masses byTrichogramma minutum was observed in maize-bare ground monocultures and polycultures of maize/bean/squash and maize/clover. Parasitism rates were 1.9 times higher in monocultures than in polycultures; seasonal phenology of parasitism, however, was similar in both. Parasitism first occurred during the late whorl/early tassel stage of maize; peak parasitism occurred during the mid to late tassel stage, and then dropped off rapidly. We speculate that direct predation of egg masses, and ammensal preemptive competition for egg masses byColeomegilla maculata may have contributed to the decline in parasitism rates in both monocultures and polycultures during the latter part of the season.      

Separating the Effects of Experience, Size, Egg Load, and Genotype on Host Response in Trichogramma (Hymenoptera: Trichogrammatidae)

The effects of experience, egg load, and wasp size on the response of four strains of Trichogramma nr. brassicae (Hymenoptera: Trichogrammatidae) to three economically important hosts, Heliothis punctigera (Noctuidae), Phthorimaea opercullela (Gelechiidae), and Sitotroga cereallela (Gelechiidae) were investigated. Experience effects due to rearing host and oviposition were considered in all combinations of host species. Both these effects altered response levels to low-ranked hosts but not to highly preferred hosts. Size was correlated with host response in some strains; larger females took more encounters with a host before accepting it, while egg load was not correlated with number of host encounters. However, egg load, rearing host, and size all affected acceptance of the low-ranked host S. cereallela. Females were more likely to accept this host if they were reared on S. cereallela, had a small size, and had a high egg load. Effects were consistent across strains, although overall acceptance levels differed among strains.     

Malic enzyme,phosphoglucomutase and phosphoglucose isomerase isozymes inTrichogramma [Hym.: Trichogrammatidae]

ME, PGM and PGI electrophoretic banding patterns in 20 laboratory cultures representing 14 species ofTrichogramma were studied. Variations in PGM were found inT. exiguum, T. marylandense, andT. pretiosum. PGI also showed variation inT. exiguum, T. marylandense, T. minutum, andT. parkeri. However, ME variations were found only inT. pretiosum. Based on progeny analyses, we concluded that ME is a tetramer inTrichogramma with fast and slow alleles at a single locus, and that both PGM and PGI have a single locus and each has four alleles. PGM is a monomer, but PGI is a dimer.

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Résumé Les bandes électrophorétiques de l'enzyme malique, de la P.G.M. et de la P.G.I. ont été étudiées chez 20 souches de laboratoire représentant 14 espèces deTrichogramma. Des variations de la P.G.M. ont été trouvées chezT. exiguum, T. marylandense etT. pretiosum. La. P.G.I. montre aussi des variations chezT. exiguum, T. marylandense, T. minutum etT. parkeri. Par contre, des variations de l'enzyme malique ne sont trouvées que chezT. pretiosum. En nous basant, sur l'analyse de progénitures, nous avons conclu que l'enzyme malique est un tétramère chezTrichogramma comprenant un allèle “lent” et un alléle “rapide”, à un seul locus, et que la P.G.M. et la P.G.I. ont chacune un seul locus à quatre allèles. La P.G.M. est un monomère mais la P.G.I. est un dimère.

     

The potential of trehalose to replace insect hemolymph in artificial media for Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae)

Insect additives have been shown to improve the value of artificial media for Trichogramma species, but at the same time maintain dependence on parallel cultures of host insects. In the present study, Trichogramma dendrolimi Matsumura was reared in vitro from egg to adult on artificial media with different contents of pupal hemolymph of Chinese oak silkmoth Antheraea pernyi (Guérin‐Méneville) and with supplements of distilled water, or of trehalose dissolved in water or in Grace's insect medium. The results indicated insect hemolymph was the key component of artificial medium. Developmental parameters, including rates of parasitism, pupation, adult emergence and normal adults, and numbers of produced adults, were increased on media supplemented with trehalose even when the proportion of pupal hemolymph was reduced. Two artificial media, the first containing 30% hemolymph and 10% trehalose in water with 98.9% parasitism rate, 77.7.0% pupation rate, 77.2% emergence rate, 80.0% normal adult rate and 333 produced adults, and the second containing 25% hemolymph and 15% trehalose in Grace's insect medium with 97.8% parasitism rate, 91.0% pupation rate, 85.2% emergence rate, 76.1% normal adult rate and 757 produced adults, were believed to hold potential to mass produce T. dendrolimi. The use of trehalose to partially replace pupal hemolymph in artificial medium of this and other Trichogramma species may contribute to a significant reduction in their production cost and may as such help to evade problems related to short supplies of lepidopteran eggs, which currently constitute the main factitious host for the mass rearing of the parasitoids.     

Flight activity assessment of the egg parasitoidTrichogramma brassicae (Hym.: Trichogrammatidae) in laboratory and field conditions

A laboratory and a field test for flight initiation ofTrichogramma brassicae Bezdenko (Hymenoptera, Trichogrammatidae) (synonymous toT. maidis Pintureau et Voegele) were developed with the aim to establish a simple, cheap and quick flight quality control method forTrichogramma producers. The flight quality of four strains ofT. brassicae reared onEphestia kuehniella Zeller eggs were compared. The material tested consisted of four strains: two strains reared for two (F2) and 39 to 42 (F39–42) generations onE. kuehniella eggs without storage treatment, a diapause strain reared six generations (F6) onE. kuehniella eggs and a commercial strain also reared onE. kuehniella eggs whose production and storage conditions were unknown. Clear differences in flight activity among strains were observed. Both, the F2 and commercial strain showed significantly better flight activity under laboratory conditions compared to the other strains. Flight field cage experiments were made for comparison between field and laboratory results. Similar differences among strains in field cage experiments were observed when compared to laboratory tests.     

Incidence of parasites ofLymantria obfuscata [Lymantriidae: Lepidoptera] in Kashmir

Incidence of parasites ofLymantria obfuscata Walker [Lymantriidae: Lepidoptera] was studied in Kashmir during 1983 and 1984. The only egg parasite reared wasAnastatus kashmirensis Mathur parasitising between 4.49 to 11.92 percent of eggs. From 15 study sites as many as 10475 larvae of different stages and pupae were collected and reared in laboratory.Exorista rossica [Tachinidae: Diptera] was recorded to parasitize upto 8.42 per cent of larvae compared to 0.89 percent byCompsilura sp.Tetrastichus sp. [Eulophidae: Hymenoptera] was observed to be most dominant of the 6 pupal parasites, accounting for 33.41 percent of the measured parasitism, followed byPimpla sp. [Ichneumonidae: Hymenoptera] andTheronia atalantae atalantae [Ichneumonidae: Hymenoptera] which parasitized 6.84 and 4.03 per cent of pupae respectively.Brachymeria intermedia Nees [Chalcididae: Hymenoptera] was recorded to parasitize upto 2.98 per cent whereasBrachymeria lasus Walker recorded for the first time in Kashmir was found to parasitize up to 2.01 per cent, but was not widely distributed in the State.     

Propagation of the Colorado potato beetle [Col.: Chrysomelidae] egg parasiteEdovum puttleri, [Hym.: Eulophidae]

The parasitic wasp,Edovum puttleri Grissell, was successfully reared onLeptinotarsa decemlineata (Say) in the laboratory and increased in sufficient numbers for inoculative release studies in the spring and summer. The effects of temperature on parasite development, and host-parasite ratios in the laboratory are presented. The sex ratio of parasites reared in the laboratory are compared to those released and recovered in the field.     

Enzymatic analysis of the genusTrichogramma (Hym.: Trichogrammatidae) in Europe

The genusTrichogramma includes numerous species which parasitize primarily the eggs of Lepidoptera worldwide. Thirteen European species were characterized biochemically to improve the systematic basis of this genus. Three enzyme systems, studied by electrophoresis, provided characters which discriminate among species. Nei distances were calculated to estimate the relationships among these species. Esterase bands proved to be a very reliable technique for discriminating among closely related species when morphological characters are not evident. The within and between population variability of isozyme patterns was greater than previously assumed forTrichogramma. The results allowed the affinity of some species to be reexamined.

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Résumé Le genreTrichogramma comprend de nombreuses espèces qui parasitent les œufs d'insectes, surtout de Lépidoptères, dans le Monde entier. Treize espèces européennes ont été caractérisées biochimiquement pour améliorer les connaissances en systématique chez ce genre. Trois systèmes enzymatiques, étudiés par électrophorèse, ont fourni des caractères qui discriminent les espèces. Afin d'apprécier les relations existant entre ces espèces, des distances de Nei ont été calculées. Les estérases se sont révélées être de bon caractères pour identifier les espèces morphologiquement très proches. La variabilité à l'intérieur des populations est plus importante que ce qui était jusque-là admis. Les résultats ont conduit à réexaminer le contenu de certains groupes d'espèces.

     

Life history,immature morphology and adult behavior ofTelenomus solitus [Hymenoptera: Scelionidae]

The results of laboratory studies on the life history, morphology of immature stages, effects of food and water on adult longevity, host age preference for oviposition, parthenogenesis, and adult behavior ofTelenomus solitus Johnson are presented.Telenomus solitus completed its development in 10.8 days (egg, 0.3 day; 1^st instar, 2.7 days; 2^nd instar, 3.7 days; and pupa, 4.1 days). The adults lived longest when provided with both honey and water. Without food, they survived less than 24 h. Parasitization of host eggs varied significantly with their age, being highest in 42 h old eggs. Fewer than 10% of eggs older than 60 h were parasitized successfully. The periodicity of oviposition was unimodal; it occurred throughout the 24 h period and peaked in the late photophase. Females ofT. solitus are arrhenotokous. The behavioral sequences during courtship, mating, and oviposition are described.      

Introduction,colonization and establishment ofLysiphlebus testaceipes [Hymenoptera: Aphidiidae], in Argentina

The introduction, colonization, and establishment ofLysiphlebus testaceipes (Cresson) for the biological control ofSchizaphis graminum (Rondani). in Argentina is briefly discussed.     

Parasitism ofLeptinotarsa decemlineata [Coleoptera: Chrysomelidae] byEdovum puttleri [Hymenoptera: Eulophidae] in different cultivars of eggplant

Experiments were conducted to quantify parasitism of Colorado potato beetle,Leptinotarsa decemlineata (Say), by the egg parasitoid,Edovum puttleri Grissell, on 3 different cultivars of eggplant,Solanum melongena L. Levels of parasitism were higher (P<0.05) on ‘Black Pride’ than on other cultivars. The percentage of egg masses that were parasitized was 1.2-fold higher (P<0.05) on ‘Black Pride’ than on ‘Harris Special’ and ‘White’. The number of eggs per mass that were parasitized was 1.3- and 1.4- fold greater (P<0.05) on ‘Black Pride’ than on ‘Harris Special’ and ‘White’, respectively. The percentage of eggs that were parasitized per mass and percentage of emerged adult parasitoids did not differ (P>0.05) among cultivars; between 2.1- to 2.6- fold more females than males emerged from eggs on all cultivars during the growing season.Edovum puttleri suppressed the 2nd generation ofL. decemlineata on ‘Black Pride’ and ‘Harris Special’, but did not suppress populations on ‘White’.      

Effect of insecticides on the emergence ofTrichogramma Brasiliensis [Hymenoptera: Trichogrammatidae] from parasitized host eggs

The effect of 9 insecticides recommended for the control of cotton bollworms was studied, under laboratory conditions, on the emergence ofTrichogramma brasiliensis Ashmead from the parasitized eggs ofCorcyra cephalonica (Stainton) of different age groups. The insecticide concentrations tested were equivalent to those recommended for field application viz. phenthoate 0.14%, phosalone 0.15%, endosulfan 0.25%, permethrin 0.014%, monocrotophos 0.13%, fenvalerate 0.014%, cypermethrin 0.014%, fenitrothion 0.30% and quinalphos 0.14%, quinalphos and fenitrothion caused complete inhibition of emergence of the parasitoid from parasitized host eggs of all ages (1 to 7 days); but in general, adverse effect of insecticides on the disruption of emergence decreased with the advancement in the age of the parasitized eggs. For 1 day old parasitized host eggs, emergence ofT. brasiliensis adults varied from 33 to 57% for the remaining 7 treatments. For the 7 days old parasitized host eggs, emergence of parasitoids from the treatments with endosulfan, phosalone and phenthoate was similar to that from control. However, 46 to 59% inhibition of emergence was observed for permethrin, monocrotophos and cypermethrin. Fenvalerate treatment also significantly inhibited the emergence but at a comparatively lower level (40%). Out of 9 insecticides tested, phosalone and fenvalerate were considered to be relatively safe toT. brasiliensis.      

Development ofTrichogramma brasiliensis [Hym: Trichogrammatidae] on eggs of radiation sterilized females of potato tuberworm,Phthorimaea operculella [Lep.: Gelechiidae]

Trichogramma brasiliensis (Ashmead) could be successfully reared on the eggs laid by gamma-irradiated sterile ♀ of the potato tuberworm,Phthorimaea operculella Zeller. Even after rearing 10 generations of the parasitoid on such eggs there were no adverse effects on various developmental parameters.      

Observations on the oviposition behaviour ofGoniozus sensorius [Hymenoptera: Bethylidae] a parasite ofDiaphania indica [Lepidoptera: Pyralidae]

Goniozus sensorius Gordh (Hymenoptera: Bethylidae) was recorded as a major parasite of the pumpkin caterpillar,Diaphania indica (Saunders) (Lepidoptera: Pyralidae). This paper provides detailed information on the oviposition behaviour ofG. sensorius. Prior to oviposition, the parasite temporarily paralyses the host larva. The paralysed condition lasts for about 2 h. The egg laying process on each larva requires 30 to 60 min. The maximum number of eggs are laid on the 6^th and 7^th segment, and none in the terminal segments. Generally, oviposition is restricted to 1 segment of the host larva and occasionally on 3 segments. The maximum number of eggs are laid on the 2^nd and 3^rd day after emergence and the mean number of eggs laid on each host larva was 7.1.     

Selection of suitable trichogramma strains to control the codling mothCydia pomonella and the two summer fruit tortrix mothsAdoxophyes orana,Pandemis heparana [Lep.: Tortricidae]

Simple laboratory methods to select candidateTrichogramma strains for use in biological control were tried. 17 strains were screened for their suitability against the codling mothCydia pomonella L. as well as the 2 summer fruit tortrix mothsAdoxophyes orana F.R. andPandemis heparana Schiff. In one set of experiments, the capacity ofTrichogramma to parasitize each of these target pests was examined, in another set, the preference ofTrichogramma to contact and parasitize the target pests compared to the standard mass rearing hostSitotroga cerealella was assessed in choice experiments. A strain ofTrichogramma dendrolimi from the People's Republic of China was found to have the highest fecundity with all the 4 hosts tested. In choice experiments, however, this strain was shown to have a near equal preference between the target tortrix pestsC. pomonella, A. orana and the replacement hostS. cerealella. 11 localTrichogramma strains collected from fruit orchards and vineyards in different locations in the Federal Republic of Germany were reared separately. Four of these local strains, one identified asT. embryophagum, showed clear preference to the tortrix pestsC. pomonella andA. orana compared toS. cerealella. The preference of one of these strains was particularly strong and amounted to a near total rejection ofS. cerealella eggs in the presence of any of the 2 tortrix pests. The remaining 12 strains had weaker parasitization capacity and/or less preference to the target pests. Four of the strains tested in these experiments, includingT. dendrolimi andT. embryophagum, were mass reared and released in apple orchards between 1984 and 1986. The results of these field experiments are planned to be published in this journal. Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

In vitro rearing ofTrissolcus basalis [Hym., Scelionidae] an egg parasitoid ofNezara viridula [Hem., Pentatomidae]

In vitro rearing of the egg parasitoidTrissolcus basalis (WOLL.) from eggs collected on the natural hostNezara viridula (L.) was initiated. Several oligidic diets containing insect material (Manduca sexta hemolymph or host egg content) were tested. Our initial medium with 50% hemolymph induced a high egg mortality, but by decreasing the hemolymph concentration, increasing the hen egg yolk concentration and adding 15% of free amino acids mixture, a hatching rate of 85% of the parasitoid eggs was obtained with 39% reaching the second instar and 33% the third instar. In a medium without hemolymph, but with 18% liquid from parasitized host eggs we obtained 90% to 100% hatching, 25 to 27% reaching the second instar and 8% the third instar. We did not obtain pupation from eggsin vitro, but did get pupae and adults from larvae rearedin vivo to second instar and transfered to anin vitro system.      

RearingTetrastichus gallerucae [hymenoptera: Eulophidae] for biological control of the ELM leaf beetleXanthogaleruca luteola

Tetrastichus gallerucae (Fonscolombe) was collected in southern France in 1985 and is being reared at the Division of Biological Control in Albany, Ca for use against the elm leaf beetle (ELB),Xanthogaleruca luteola (Müller) in northern California. This egg parasitoid can be reared easily by keeping the beetle eggs on a moist substrate to prevent desiccation and by inhibiting the growth of mold with air currents. A laboratory colony of ELB adults provides a constant supply of fresh eggs for the parasitoids. In 1985 and 1986 over 80,000T. gallerucae were released at 17 sites.