Biology ofAgrothereutes tunetanus Haber. [Hym. Ichneumonidae] an ectoparasite ofOrgyia dubia Tausch. [Lep. Lymantriidae]

Résumé Les auteurs décrivent le cycle évolutif et le comportement de ponte de l'Agrothereutes tunetanus Haber. (Ichneumonidae, Cryptinae) dans les conditions de laboratoire (25°C et 50–60% H.R.). Le développement des œufs des larves et des nymphes, le comportement des stades larvaires, les habitudes alimentaires, l'accouplement et le comportement pendant l'oviposition sont décrits. A. tunetanus est un parasite de l'Orgyia dubia Tausch., attaquant le dernier stade larvaire de la femelle après que celle-ci ait tissé son cocon, mais avant la nymphose. Le même degré d'activité de ponte du parasite est provoqué par le dernier stade larvaire et la nymphe des femelles h?tes. Une moindre activité est suscitée par les femelles m?res dans les cocons et le dernier stade larvaire male, tandis que l'activité de ponte provoquée par les nymphes males est presque nulle. Le nombre moyen d'œufs pondus par une femelle durant une seule attaque (entre 3 et 4) ne dépend pas (de manière significative) du nombre de cocons présents. Le nombre d'attaques effectuées parA. tunetanus en 24 heures dépend de la quantité de cocons disponibles, les facteurs limitants sont le nombre d'œufs m?rs dans de la femelle gravide et la quantité d'œfus pondus pendant chaque attaque. Avec 6 cocons en 24 heures, une femelle, au maximum de sa fécondité, arive à une moyenne de 3,27 attaques. La fécondité d'une femelle est en moyenne de 308 œufs.

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Part of the M. Sc. thesis done under the supervision of the first author and submitted to the Department of Zoology of the Tel-Aviv University.     

Seasonal history ofMacrocentrus grandii [Hym.: Braconidae] andEriborus terebrans [Hym.: Ichneumonidae], two parasitoids of the European corn borer,Ostrinia nubilalis [Lep.: Pyralidae]

The seasonal histories and phenological relationships of European corn borer,Ostrinia nubilalis (Hübner), and its 2 parasitoids,Macrocentrus grandii (Goidanich) andEriborus terebrans (Gravenhorst) were studied in southcentral Minnesota. Both parasitoids overwintered in mature borer larvae, broke diapause, completed development, and emerged at the same time as did borer adults. Thus the 1st generation parasitoids coincided with the peak abundance of their preferred larval instars of the 1st host generation. Both parasitoids had a 2nd generation, matching the bivoltinism ofO. nubilatis in Minnesota. The activity of 2nd generationE. terebrans was before the peak 2nd generation borer moth flight and was not synchronized with the peak abundance of 2nd generation borer larvae. The peak activity of 2nd generationM. grandii occurred after the peak 2nd generation borer moth flight and was fully synchronized with the peak abundance of 2nd generation borer larvae. Thus,M. grandii has both generations synchronized with the host seasonal history, and was the more effective of the 2 parasitoids.     

Laboratory studies ofDiadegma cerophagus [Hym.: Ichneumonidae], a parasite introduced to controlPlutella xylostella [Lep.: Hyponomeutidae] in Malaysia

Laboratory studies were conducted to determine some of the attributes ofDiadegma cerophagus Gravenhorst, a parasite introduced to controlPlutella xylostella (L.). Longevity studies have shown that ♂ and ♀ could live for 40 and 73 days respectively when fed on diluted honey. The parasite is capable of attacking an average of 117±10 caterpillars per ♀. The number of caterpillars attacked per ♀ is dependent on the life span of the ♀. The average area of discovery ofD. cerophagus, based on studies of single searching parasites, was found to be 1.20±0.21. The area of discovery was found to decrease with increase in parasite or host density. However, the k-value would increase with increasing parasite density and decrease with increasing host density. The life-cycle ofD. cerophagus is as follows: egg stage, 1.5 to 2 days; larval stage, 5 to 8 days and pupal stage, 6 to 9 days. There are 4 larval instars and the duration of each instar is dependent on the age of the host attacked. The duration of the larval stage averaged 6.5 days when 1- and 2-day old caterpillars were exposed toD. cerophagus and took 5 days when 3- and 4-day old caterpillars were exposed.     

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.     

The effect of parasitism byHyposoter didymator [Hym.: Ichneumonidae] on food consumption and utilization bySpodoptera litura [Lep.: Noctuidae]

The effect of parasitism byHyposoter didymator (Thunb.) [Hym.: Ichneumonidae] on food consumption and utilization bySpodoptera litura (Fb.) [Lep.: Noctuidae] was studied for seven days, during which the parasitoid completed its larval development. Food consumption, weight gained and faeces produced were significantly less in parasitized larvae than in unparasitized larvae after the 4^th day following parasitization. Approximate digestibility was higher in parasitized larvae after the 2^nd day following parasitization. Efficiency of conversion of ingested and digested food into body weight was greater in unparasitized larvae after the 2^nd day of parasitization. There seems to be a definite immediate advantage to the crop on releasing the parasitoid due to the reduced consumption of food. Contribution No. 46004 of Biological Control Centre (NCIPM), Bangalore 560 024.     

Campoletis sonorensis [Hym.: Ichneumonidae] as a parasitoid ofSpodoptera frugiperda [Lep.: Noctuidae]: Host stage preference and functional response

The response of the parasitoidCampoletis sonorensis (Cameron) as a natural control agent of the fall armyworm,Spodoptera frugiperda (J. E. Smith), was evaluated at 6 host densities and 2 temperature regime. A type-II functional response was exhibited by femaleC. sonorensis in response to varying densities of all armyworn larvae at both temperatures. Significantly more larvae were parasitized at 25°C for the host densities of 60 and 75, than for the same densities at 30°C. Third instar fall armyworm larvae were found to be the preferred stage for parasitization byC. sonorensis. This research was supported by funds from HATCH project no. H-368 as allocated to the Georgia Agricultural Experiment Station.     

RearingGlypta fumiferanae [Hym.: Ichneumonidae] on a multivoltine laboratory colony of the western spruce budworm (Choristoneura occidentilis) [Lep.: Tortricidae]

Methods were developed for rearingGlypta fumiferanae Viereck on a nondiapausing laboratory colony of the western spruce budworm,Choristoneura occidentalis Freeman. Both host and parasite are univoltine and undergo diapause in nature. In this study, the parasite's voltinism was synchronized with that of a nondiapausing host.G. fumiferanae mated readily in the laboratory, and 5 consecutive generations were reared with an average generation time of less than 8 weeks-much less than the 23 weeks needed for 1 generation to develop in the field. Developmental times are reported, and some aspects of behavior described.     

Interactions betweenPleolophus basizonus andLophyroplectus luteator [Hym.: Ichneumonidae], two parasites ofNeodiprion sertifer [Hym.: Diprionidae]

Females ofPleolophus basizonus (Gray.) show a very strong avoidance of cocoonedNeodiprion sertifer (Geoff.) prepupae in which there are eggs, larvae or prepupae ofLophyroplectus luteator (Thunb.). When multiparasitism does occurP. basizonus is the successful competitor but adults are much smaller than those from hosts that were not multiparasitized.     

Host recognition by the gypsy moth [Lymantria dispar] [Lep.: Lymantriidae] hyperparasite,Eurytoma appendigaster [Hym.: Eurytomidae] of cocoons ofCotesia melanoscela [Hym.: Braconidae]

Artificial and modified natural hosts were exposed to females of the gypsy moth [Lymantria dispar (L.)] hyperparasite,Eurytoma appendigaster (Swederus), to investigate its host recognition behavior on the primary host, which are cocooned larvae of the gypsy moth parasite,Cotesia melanoscela (Ratzeburg). Material(s) which caused drilling behavior by the hyperparasite on host cocoons were extracted with both polar and non-polar solvents. However, cocoons washed with large volumes of solvent still caused substantial drilling activities by females, suggesting that additional cues may be important. Results suggest that host recognition in this hyperparasite involves a variety of host characteristics.      

Biology ofPhanerotoma hendecasisella [Hym: Braconidae] a parasitoid ofDiaphania indica [Lep.: Pyralidae]

Studies were conducted on the solitary egg-larval endoparasitoidPhanerotoma hendecasisella Cam. [Hymenoptera: Braconidae] to determine its biology onDiaphania indica (Saunders) [Lepidoptera: Pyralidae]. Larvae pass through 3 stages as determined by the shape and size of the mandibles. Mean developmental period from egg to adult was 26.51 days at 26.06 °C and 73.88% RH. There is no preoviposition period. The sex ratio was 1∶1.12 (male/female). Mean adult longevity was not different for ♂♂ and ♀♀.      

Introduction and establishment ofApanteles flavipes [Hym.: Braconidae] onDiatraea saccharalis [Lep.: Pyralidae] in texas

The braconid parasite,Apanteles flavipes (Cameron), was introduced into the Lower Rio Grande Valley of Texas in 1977 and has become established onDiatraea saccharalis (F.) attacking 4 species of host plants. Approximately 71% of the 26,971 adult parasites released were released in sugarcane,Saccharum officinarum L., with the remainder being released on field corn,Zea mays L., broomcorn,Sorghum vulgare technicum (Koern.) and Johnson grass,Sorghum halepense (L.). Recoveries indicate dispersal of at least 4 km from release sites.     

Genetic variability in arrhenotokous and thelytokous forms ofMesochorus nigripes [Hym.: Ichneumonidae]

Electrophoresis of isozymes was carried out to determine the degree of genetic variability in arrhenotokous and thelytokous forms ofMesochorus nigripes. Although the over-all heterozygosity (H_a) for 12 loci in 10 enzyme systems was 0.187 for the arrhenotokous form and 0.103 for the thelytokous form, a paired comparison t-test showed no significant difference. Nei's coefficient of genetic identity between these 2 forms I=0.982.

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Résumé Afin de déterminer le degré de variabilité génétique chez les formes arrhénotoques et thélytoques deMesochorus nigripes, les isozymes ont été étudiés par électrophorèse. Bien que le taux d'hétérozygotie (H_a), calculé à partir de 12 loci appartenant à 10 systèmes enzymatiques, soit de 0,187 chez la forme arrhénotoque et de 0,103 chez la forme thélytoque, aucune différence significative n'existe selon le test ≪t≫. Le coefficient d'identité génétique de Nei entre ces deux formes est: I=0,982.

     

Commercial inundative releases ofTrichogrammatoidea cryptophlebiae [Hym.: Trichogrammatidae] againstCryptophlebia leucotreta [Lep.: Tortricidae] in citrus

Inundative releases of the egg parasitoidTrichogrammatoidea cryptophlebiae Nagaraja were made againstCryptophlebia leucotreta (Meyrick) on 5 commercial citrus farms in the western Cape Province, South Africa, over 2 successive seasons. A target release volume of 80 000 parasitoids ha⁻¹ week⁻¹ was established for releases over 29 and 33 weeks during the 2 seasons. Total seasonal volumes reached an equivalent of 2.3 and 3.8 million parasitoids ha⁻¹ respectively. Compared with check treatments on each farm, larval population size was reduced in the release areas by 54% in the 1^st and by almost 60% in the 2^nd season. Percentage crop loss was reduced by 49.4±12.4 and 61.1±8.3% respectively. Treatment effects were clearly related to increases in rate of parasitism measured in both artificially-placed and in nativeC. leucotreta egg populations. Treatment efficacy is similar to that obtained with applications of chitin synthesis inhibitors but parasitoid production costs are 30% of insecticide costs. Manual distribution of parasitoids is labour intensive, however, and further studies should investigate whether inoculative releases at higher rates per week over a shorter period, are effective.      

Biology ofMicroplitis mediator [Hym.: Braconidae] a gregarious endoparasite ofAgrotis segetum [Lep.: Noctuidae]

Microplitis mediator (Haliday) a gregarious endoparasite was recorded for the first time fromAgrotis segetum (Schiff) in Ankara, Turkey. The female parasites found their hosts by responding to the faeces of the caterpillars. An average, females laid 15.5±1.6 eggs in the bodies of their hosts. The newly laid eggs were elongated, oval in shape and 0.23±0.004 mm long and 0.07 mm wide. They hatched in 5, 4 and 3 days at 20±2°C, 25±2°C and 30±2°C respectively when maintained at 60–70% R.H. and 14∶10 light∶dark regime. At the same temperatures, the larval stage lasted for 24.9±0.6, 18.2±0.4 and 17.1±0.5 days respectively. The prepupal stage was completed in 2 days at 25±2°C, whereas the prepupal and pupal (cocoon) stage lasted 10.9±0.2, 7.0±0.1 and 6.2±0.1 days respectively at the temperatures mentioned above. The adults started mating and feeding shortly after emergence. Female parasites started laying after one day, 7–11 hours and 5–7 hours at the temperatures stated above. At these temperatures females lived for 10.8±0.2, 5.4±0.1, 4.6±0.1 days and laid on average 556, 484 and 363 eggs respectively, whereas the males survived 10.5±0.3, 4.7±0.1 and 4.4±0.1 days respectively.      

Release ofTelenomus remus [Hym. scelionidae] againstSpodoptera frugiperda [Lep.: Noctuidae] in Florida,U.S.A.

Telenomus remus Nixon, a scelionid egg parasite of Lepidoptera, was released against fall armyworm,Spodoptera frugiperda (J. E. Smith), near Homestead, Florida U.S.A. from May 1975 — May 1977. A small percentage (4.5) of the egg masses collected were parasitized byT. remus, however no recoveries were made in the months following the final release. An egglarval parasite,Chelonus insularis (=texanus) (Cresson), was reared from 50% of the larvae from eggs collected.T. remus apparently was not established in Florida.

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Résumé Telenomus remus Nixon, scelionide parasite des œufs de lépidoptères, a été laché contreSpodoptera frugiperda (J. E. Smith) près de Homestead en Floride, de mai 1975 à mai 1977. Un faible pourcentage des pontes récoltées (4,5%) se révélèrent parasitée parT. remus, cependant aucun parasite ne fut retrouvé dans les mois qui suivirent le dernier lacher. Un parasite ovo-larvaire,Chelonus insularis (=texanus) (Cresson) a été obtenu à partir de 50% des larves issues des œufs récoltés. ApparemmentT. remus n'a pas été établi en Floride.

     

Oviposition pattern byCotesia ayerzai [Hym.: Braconidae] onAscia monuste [Lep.: Pieridae] under laboratory conditions

Various aspects of the parasitims of caterpillars ofAscia monuste orseis byCotesia ayerzai, were studied in laboratory choice tests. Individual ♂♂ were found to be extremely variable in ovipositional duration, as well as in the number of eggs oviposited. To simulate parasitoid dispersal, or low host density, we isolated ♂♂ for 60 min following initial exposure and compared our tests with ♂♂ which had not been isolated. No differences in (1) the number of eggs oviposited per host instar; (2) the conditional probability of host encounter; (3) host acceptance; and (4) the conditional probability of instar specific parasitism were found between these groups. Held ♂♂ did, however, reject hosts after ovipositor insertions in a higher proportion.      

Predators ofBathyplectes curculionis [Hym.: Ichneumonidae], a parasite ofHypera postica [Col.: Curculionidae]

Invertebrate predation was shown to be the greatest mortality factor on diapausing larvae ofBathyplectes curculionis (Thomson) in Illinois. Feeding tests were conducted in which specific predators were determined by exposingB. curculionis larvae to various surface dwelling invertebrates found in alfalfa fields. In addition, field plantings of parasite larvae in modified cages were used to determine the size of predators, and also, if litter density affected predation. Seasonal activity ofB. curculionis predators was also measured from 4 April 1975 to 18 November 1975 via 15 pitfall traps located in 3 alfalfa fields. Results from feeding studies showed that spiders,Cicindelidae, Formicidae and smallStaphylinidae never preyed uponB. curculionis larvae in cocoons. The 2 groups of predators which consumed the larvae were field crickets,Gryllus pennsylvanicus Burm., and various species ofCarabidae. Predation on the parasite larvae planted in the field was mainly caused by moderately sized invertebrates, and was not significantly affected by litter density. The greatest number of total predators (G. pennsylvanicus plus Carabids) caught/day/pitfall trap, and the greatest predation on field-plantedB. curculionis larvae, occurred concurrently during September and October. These data suggest that predation during September and October may be significant in reducing field populations of diapausing parasite larvae. Based on feeding studies and pitfall trap catches,Gryllus pennsylvanicus and the carabids,Abacidus permundus (Say),Evarthrus sodalis LeConte,Harpalus pennsylvanicus DeGeer andScarites subterraneus Fab., were the most important predators onB. curculionis larvae.

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Résumé Il a été montré que les prédateurs invertébrés sont le plus grand facteur de mortalité des larves en diapause deBathyplectes curculionis (Thomson) en Illinois. On a fait des essais alimentaires dans lesquels on a déterminé des prédateurs spécifiques en exposant les larves deB. curculionis à divers invertébrés trouvés dans les champs de luzerne. De plus, des larves du parasite, dans des cages modifiées implantées dans les champs, ont été employées pour vérifier la taille des prédateurs et aussi pour savoir si la densité de la litière a influencé les prédateurs. L'activité saisonnière des prédateurs deB. curculionis a été mesurée du 4 avril 1975 au 18 novembre 1975 au moyen de 15 pièges placés dans 3 champs de luzerne. Les résultats des essais alimentaires montrent que les araignées,Cicindelidae, Formicidae et de petitsStaphylinidae n'ont jamais utilisé comme proie les larves en cocon deB. curculionis. Deux groupes de prédateurs ont consommé les larves: les grillons,Gryllus pennsylvanicus Burm., et des espèces variées deCarabidae. Pour la plupart ce sont des invertébrés de taille modérée qui ont utilisé comme proie les larves implantées dans les champs, la densité de litière n'étant pas significative. Le plus grand nombre de prédateurs au total (G. pennsylvanicus plusCarabidae) attrapés par jour et par piège et la plus grande consommation de larves deB. curculionis se sont produits concurremment en septembre et en octobre. Ces données indiquent que les prédateurs en septembre et octobre peuvent être très importants pour réduire le nombre de larves parasites en diapause. Si l'on juge selon les essais alimentaires et selon ce qu'on a attrapé dans les pièges,Gryllus pennsylvanicus et lesCarabidae, Abacidus permundus (Say)tEvarthrus sodalis LeConte,Harpalus pennsylvanicus DeGeer,et Scarites subterraneus Fab., on, constitué les prédateurs spécifiques les plus importants des larves deB. curculionis.

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This publication was supported by the Illinois Natural History Survey, The Illinois Agricultural Experiment Station, National Science Foundation, and the U.S. Environmental Protection Agency, through a grant (NSF GB-34718) to the University of California. The findings, opinions and recommentations expressed herein are those of the author(s) and not necessarily those of the University of California, the National Science Foundation and the Environmental Protection Agency.     

Studies onPrays acmonias [Lep.: Yponomeutidae] and its natural enemies in Pakistan

A survey forPrays acmonias Meyr. and its natural enemies was made in the northern hills in Pakistan. It attackedViburnum spp. in the Murree hills, Azad Kashmir and Swat. Its populations were generally low at most localities.Deraecoris sp.,Haplothrips sp. (egg predators),Apanteles sp. nr.dilectus Hal.,Elasmus hyblaeae Ferrière,Elachertus sp.,Euderus sp. andSympiesis sp. (larval parasites),Sphedanolestes sp. (larval predator),Aspergillus flavus Link andStreptococcus sp. (pathogens) attackedP. acmonias. Among theseApanteles was more common throughout the distribution area of the host and destroyed up to 13% host larvae. It appears to be a possibly promising parasite for trials in areas wherePrays spp. are pests. However, it did not parasitizePrays oleae (Bern.).

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Résumé Cette chenille qui attaque lesViburnum spp. dans les collines du Nord du Pakistan s'y trouve généralement en faibles densités.Deraecoris sp.,Haplothrips sp. (prédateurs des œufs),Apanteles sp. nr.dilectus Hal.,Elaemus hyblaeae Ferrière,Elachertus sp.,Euderus sp. etSympiesis sp. (parasites des larves),Sphedanolestes sp. (prédateur des larves),Aspergillus flavus Link etStreptococcus sp. (germes pathogènes) sont les ennemis naturels deP. acmonias. Le plus commun estApanteles, qui peut détruire jusqu'à 13% des chenilles. Il peut être un parasite intéressant pour la lutte contre desPrays spp., mais il ne parasite pasPrays oleae (Perm.).

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This work was sponsored by the Food and Agriculture Organisation of the United Nations as a part of the project entitled “Research on the control of olive pests and diseases in continental Greece, Crete and Corfu”.     

Biological comparisons between arrhenotokous and thelytokous biotypes ofMesochorus nigripes [Hym.: Ichneumonidae]

The host preferences and sex ratios ofMesochorus biotypes from Sweden and Colorado (U.S.A.) were studied in the field and laboratory. TheseMesochorus are secondary parasites ofBathyplectes spp., parasites ofHypera postica (Gyllenhal). The Colorado biotype is 100% thelytokous, and clearly prefersBathyplectes stenostigma (Thomson) as a host. Only an arrhenotokous biotype was positively detected in Sweden, and it appeared to preferB. curculionis (Thomson). However, some of the data suggest that the thelytokous biotype was probably also present in Sweden, at least inB. stenostigma. The behavioral differences and reproductive isolation of the thelytokous and arrhenotokous biotypes indicate that they are separate sibling species, even though they cannot yet be separated morphologically, and isozyme analyses were inconclusive (possibly due to a mixture of biotypes in Sweden).