Biological studies withChrysocharis parksi [Hym.: Eulophidae] a parasite ofLiriomyza spp. [Dipt.: Agromyzidae]

Biological studies withChrysocharis parksi Crawford, a parasite of agromyzid leafminers, were conducted.C. parksi successfully parasitized the following species in the genusLiriomyza Mik.,L. huidobrensis (Blanchard),L. sativae Blanchard,L. trifolii (Burgess), andL. trifoliearum Spencer. Successful parasite development was recorded from 8 plant families and 16 genera. Host plants which were suitable for leafminer development to the adult stage were also suitable for parasite development. Mean immature developmental period (egg to adult, usingL. trifolii as the host) at 21.1°, 26.7°, and 32.2° C was (for both sexes) 23, 14, and 14 days, respectively. Longevity of females provided only water was inversely related to temperature; significantly longer survival occurred at 21.1° C (5.0 days) compared to 26.7° C and 32.2° C (3.2 and 2.1 days, respectively). The addition of honey to the diet significantly improved longevity of both sexes at all temperatures. Adult female parasites which were provided an average of 33.0L. trifolii larvae per day produced an average of 135 offspring at a constant 26.7° C.C. parksi host-fed on ca. 3.7 leafminer larvae per day over an 11-day adult lifespan.      

Host-handling behavior of the parasitoid,Diglyphus minoeus [Hym.: Eulophidae], parasitizing the honeysuckle leaf-miner,Phytomyza lonicerae [Dipt.: Agromyzidae]

The host-handling behavior of individual female waspsDiglyphys minoeus which attack the larvae of the honeysuckle leaf-miner,Phytomyza lonicerae, include 4 types of behavior: probing, ovipositor insertion, host-feeding, and resting. Ovipositor insertion may either be injection of venom, probing of the host by the sensilla on the ovipositor's tip or egg laying. Three types of attacks were distinguished: oviposition attack for unparasitized larvae, host-feeding attack for unparasitized host larvae and host rejection for previously parasitized host larvae. Oviposition attack was characterized by frequent alternation between probing and ovipositor insertion, long duration of ovipositor insertion and resting, and the long duration of host-handling. Resting behavior is thought to protect the progeny against superparasitism, host-feeding by other wasps or hosts' recovery from paralysis. Host-feeding attack was characterized by frequent alternation between host-feeding and ovipositor insertion and long duration of host-feeding. Host rejection was composed mainly of probing and ovipositor insertion and short handling time.      

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.     

Temperature requirements of the chrysanthemum leaf miner,Chromatomyla syngenesiae [Dipt.: Agromyzidae], and its ectoparasitoid,Diglyphus isaea [Hym.: Eulophidae]

The development rate from egg to adult for ♂ and ♀Chromatomyia (Phytomyza) syngenesiae andDiglyphus isaea increased linearly between 19 and 25°C.D. isaea had a faster developmental rate thanC. syngenesiae between 19 and 25°C but therer was no difference at 16°C. FemaleD. isaea required 154.6 D° above the theoretical threshold of 12.80°C and maleD. isaea 152.4 D° above 12.9°C for total development from egg to adult emergence. FemaleC. syngenesiae needed 207.0 D° above 12°C and ♂ and 211.0 D° above 11.6°C for total development.      

Lachers d'Opius concolor [Hym.: Braconidae] dans des populations de printemps deDacus oleae [Dipt.: Trypetidae]

Résumé Un lacher du braconideOpius concolor Szepl. a été effectué au printemps au cours de la première génération de multiplication de la mouche de l'oliveDacus oleae Gmel. dans l'oliveraie de Delphes. Il permet de constater que: le parasite s'installe normalement aux dépens des larves réceptives (troisième stade), il est apte à parasiter les larves deD. oleae présentes en haut et en bas de l'arbre, les pontes des femelles s'étalent sur deux semaines, le parasite est susceptible d'être hébergé par les pupes qui s'enfouissent dans le sol. La mortalité larvaire naturelle due à des causes non parasitaires est importante, notamment dans les olives tombées au sol et dans celles de la partie basse et ombragée de l'arbre.

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Summary A release of the braconid parasitoidO. concolor Szepl. was made during spring (May) against the larval population of the olive fruit flyD. oleae Gmel. in a grove containing some trees which had heavily infested olive fruits which had overwintered. The parasitoid developed normally in the 3rd instar larvae of this population. Although it was present throughout the tree, during the 1st days it was more active in the upper part where 51% of receptive larvae were parasitized than in the lower where 18% were parasitized. After one week, these figures were 20% and 44% respectively. They have been calculated from counts ofDacus larvae containing either eggs or larvae.O. concolor had almost completely disappeared from the tree 2 weeks after the release because of fruit fall following high winds, although it was still possible to find both eggs and larvae in the appropriate host stages on the soil. The emergingO. concolor population was dominated by male adults, making up 74% of the numbers. The natural mortality ofD. oleae larvae not induced by the parasite factor was important in the area, especially in the fruits fallen onto the soil in which 28% of young larvae and 14% of 3rd instar larvae died. Higher mortality occurred from these factors in the upper crown than in the lower: 16% of young larvae and 7% of 3rd instar larvae died in the former situation but 7% and 2% respectively in the latter. Almost no parasitism from indigenous parasites was recorded.

     

Biology ofIphiaulax kimballi [Hym.: Braconidae], a parasite ofDiatraea grandiosella [Lep.: Pyralidae]

Iphiaulax kimballi Kirkland is a gregarious ectoparasite of the mature larval stage ofDiatraea grandiosella Dyar in Mexico. The developmental rate from egg to adult is 16.3±1.0 (x±S.D.) at 29°C. The sex ratio is 1.7∶1 (♀∶♂) in the field. Following host paralysis the female deposits 63.5±2.1 eggs during der 28.6±6.4 day adult-life span; laying 4.6±3.1 eggs on each host. Females held at 10°C lived a maximum of 3 months.     

Influence of temperature onOpius dissitus (Hym.: Braconidae), a parasitoid ofLiriomyza trifolii (Dipt.: Agromyzidae)

Rearing experiments at different temperatures (10, 15, 20, 25 and 30°C) were made onOpius dissitus Muesebeck, a parasitoid ofLiriomyza trifolii (Burgess). Temperatures between 20 and 30°C were optimal for the development ofO. dissitus, which was able to adapt to relatively high temperatures despite its holarctic origin.     

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.     

Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] in Israel

The effects of certain environmental conditions on the survival ofChelonus inanitus (L.) adults were studied in the laboratory. The longevity of the adults decreased with increase in temperature. The survival of males and females under extreme conditions of temperature and humidity was negatively correlated with the duration of exposure. For short periods of exposure the survival ofC. inanitus adults was influenced by high temperatures, the lethal exposure time decreased when the parasitoids had been exposed to high temperatures. Change in the saturation deficit did not affect the survival rate. Different kinds of food available in the field such as flowers of cotton and alfalfa, cotton nectars and excretion of common aphids, did not prolong the life span ofC. inanitus adults in comparison with parasitoids that had not received food or water. The 50% mortality of males that had been fed on cane-sugar with water, honey, flowers of alfalfa or flowers of cotton, was 15, 23, 5 and 5 days respectively, while these values for females that had been fed on the same type of food were 23, 35, 5 and 3 days respectively.     

Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] in Israel

Only one species ofChelonus Panzer,Chelonus inanitus (L.), was found to be widespread in all areas of Israel. The parasitoid was particularly widespread in alfalfa fields but also was present in cotton, sugar beet, artichoke and corn. Spodoptera littoralis (Boisd) andS. exigua (Hbn.) were the main hosts ofC. inanitus although it might develop in other Lepidoptera species. A study of its population showed that adults were present in the spring, summer and autumn but not during the winter. In most cases the population density of the parasitoid appeared to be related to that of the hosts. Parasitism and sex ratio ofC. inanitus in alfalfa fields were studied. The number of males (average of 75%) was higher than that of the females. Percentage of parasitism in larvae ofS. littoralis andS. exigua reached up to 39.8% and 13.5% respectively. The parasitism values in eggs ofS. littoralis were up to 71%.     

Natural parasitism of the chrysanthemum leaf-minerChromatomyia syngenesiae H. [Dipt.: Agromyzidae]

Twenty-one species of parasites were reared from natural populations of the chrysanthemum leaf miner,Chromatomyia syngenesiae Hardy in Southern England. A further species was reared from glasshouse crop plants infested with leaf-miners and left outside. The parasite community attacking the crop plants was otherwise similar to the natural host plant community. The relevance of this work to the biological control of chrysanthemum leaf-miner is discussed.

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Résumé Vingt et une espèces de parasites larvaires furent élevées à partir de populations naturelles de mineuses des feuilles du chrysanthèmes dans le sud de l'Angleterre. Une espèce supplémentaire fut élevée à partir de plantes provenant de serre infestée de mineuses et exposée dans les habitats naturels. Le complexe parasitaire qui s'installe sur ces plantes fut analogue en toutes autre manières à celle trouvée sur les plantes spontanées. L'intérêt de ce travail pour la lutte biologique contre les mineuses du chrysanthème est discuté.

     

Field evaluation ofAllorhogas pyralophagus [Hym.: Braconidae], imported into texas for biological control of the stalkborerEoreuma loftini [Lep.: Pyralidae] in sugar cane

The external, gregarious, braconid parasite,Allorhogas pyralophagus Marsh was mass released into field cages enclosing sugar cane infested with the pyralid,Eoreuma loftini (Dyar) to examine factors affecting parasitism rates and to assess the parasite's potential contribution to borer larval mortality. Three field experiments were conducted in July, September, and December, 1984. Total parasitism was 25.2% for the study and was the single most important source of borer mortality. Borers were equally susceptible to attack in leaf sheaths, whorls, and stalks in general, but larvae tunneling deep within stalks were parasitized less. An interaction between tunneling behavior of the borer and attack strategy of the parasite was important for parasite success.A. pyralophagus is probably unable to effect complete control ofE. loftini in sugar cane becauseA. pyralophagus is physically unable to parasitize borers deep in the stalks. However, the parasite may be useful as part of an intergrated pest management program, acting in concert with other parasite species, or attacking the borer in small-stemed grasses that serve as alternate host plants.      

Forest and laboratory evaluations of hybridizedApanteles melanoscelus [Hym.: Braconidae], a parasitoid ofPorthetria dispar [Lep.: Lymantriidae]

Hybrids ofApanteles melanoscelus (Ratzeburg) were produced from colonies originating from France, Yugoslavia, and Connecticut. All strains, as well as freshly collected “wild” Connecticut parasitoids of the same species were evaluated in the laboratory for developmental rate, host attack rate, and sex ratios. Development was significantly slower in all the laboratory strains compared to the progeny of forest collected Connecticut females. Progeny production was greater (almost 2X) for the “wild” females and the French-Yugoslavian-Connecticut hybrid than for the laboratory Connecticut strain. The proportion of females collected from the “wild” (Connecticut) strain was higher than that observed in any laboratory strain. A field test was conducted using the triple hybrid in 3 release plots with ca. 6000A. melanoscelus cocoons released per plot in central Connecticut, U.S.A. Weekly collections of gypsy moth larvae showed that the % parasitism was significantly higher in release plots than in the 3 check plots. These results suggest the value of inundative releases ofA. melanoscelus for reduction of sparse gypsy moth populations, but they did not show that hybridization of these strains produced a more effective parasitoid under forest conditions.     

In vitro rearing ofLysiphlebus fabarum [Hym.: Braconidae]

In vitro rearing of the aphid endoparasitoidLysiphlebus fabarum (Marshall) (Hymenoptera, Braconidae) was attempted. Successful permanent cultures ofAphis fabae Sc. andMyzus persicae Sulz. cells were not obtained. Therefore, parasitoid larvae were reared in 2 unnatural media rone of which included cells ofCeratitis capitata Wied. (Diptera, Trypetidae). A group of larvae was reared in a substrate to which parasitoid teratocytes had been added. SinceLysiphlebus fabarum females did not oviposit into paraffin droplets including the substrates, the larvae were directly transferred from parasitized aphids into the rearing media. Several larvae reached the final instar, but only 2 out of the 48 tested in the 3 substrates became adults. The meaning of teratocytes inin vitro rearing of Aphidiine, Braconids is discussed. This work was supported by a grant from the italian Ministry of Education (M.P.I. 40%).     

Biological control ofCuscuta spp. II. Biology and host-plant range ofMelanagromyza cuscutae Hering [Dipt. agromyzidae]

Résumé Melanagromyza cuscutae Hering était considéré comme un agent biotique prometteur pour la lutte biologique contre la Cuscute. Dans les conditions de laboratoire, les imagos en présence de Cuscute et d'une solution de miel s'accouplent 1 à 4 jours après leur émergence, habituellement le matin, pendant 2 à 5 heures. Les femelles pondent 2 à 8 jours plus tard et cela durant 6 à 15 jours; au cours de leur vie (8 à 21 jours), chaque femelle dépose 11 à 132 œufs avec un maximum de 31 œufs dans une journée. L'éclosion des œufs se produit après 1 ou 2 jours. Les 3 stades larvaires et le stade pupe durent respectivement 7 à 8 et 8 à 13 jours. La ponte détermine une hyperplasie des cellules de la plante h?te et le forage des tiges entra?ne leur durcissement, leur noircissement puis leur dessiccation sur 10 cm. Un fort parasitisme (60–70%) par 6 espèces d'Hyménoptères a été observé en mai et juin. La Mouche était active en mars-avril et septembre–novembre en plaine et en juin–juillet en montagne, lorsque les températures étaient comprises entre 17 et 23°C. Les périodes défavorables sont passées à l'état de pupe dans les tiges minées. Les tests de spécificité ont montré que les femelles fécondées refusent de pondre dans 81 espèces de plantes appartenant à 42 familles. Seuls,Tradescantia sp. etIpomoea batatas re?urent chacune 1 œuf qui évolua normalement tandis que la larve n'a pas poursuivi son développement. L'alimentation de l'adulte surCuscuta semble essentielle pour la reproduction: en l'absence de cette plante, l'accouplement et le développement ovarien n'ont pas lieu.      

The release ofOpius concolor andO. Concolor var.Siculus [Hym.: Braconidae] against the spring generation ofDacus oleae [Dipt.: Trypetidae] on Corfu

Releases ofOpius concolor Szepl. andO. concolor var.siculus Mon. were carried out in the spring to determine if they could be used as a biological control agent against the heavy infestation ofDacus oleae Gmel. which occurs on Corfu at that time. At an initial density of 300–400 parasites per tree the mean parasitism rates of 3rd stage larvae ranged from 30–50% in the 1st week following the release, indicating thatOpius could work well in the spring in the tall trees with large numbers of ripe and heavily infested fruits that are found on Corfu.     

A review of haliday species ofMicroctonus [Hym.: Braconidae,Euphorinae]

A neotype based on aWesmael specimen is designated forMicroctonus aethiops (Nees).M. aethiops of authors is described asaethiopoides, new species. Lectotypes are designated forM. secalis (Haliday) andcerealium (Haliday). The namecerealium is suppressed as a synonym of the namesecalis and the types ofsecalis andbrevicollis (Haliday) are redescribed.     

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.

     

Cold tolerance of coccons ofAllorhogas pyralophagus [Hym.: Braconidae]

Cold tolerance studies were conducted under laboratory conditions for coccons ofAllorhogas pyralophagus Marsh, a Mexican parasitoid of graminaceous borers. By storage, developmental time (from cocoon to adult emergence) could be extended by 2 to 6 times. However, cocoons stored for more than 14 days at 2°C failed to survive, while at 5 and 10°C, about 50% emergence was recorded for upto 21 days of storage. With respect to survival and adult longevity, 10°C seemed to be the most suitable storage temperature. Pre-emergence period was also significantly increased by storing cocoons for 21 to 35 days at this temperature. Sex-ratio of emerging adults was not significantly affected by storage. Fecundity was adversely affected in all the treatments except in the case of females emerging from cocoons stored at 5°C for 7 days. The progeny of parasitoids which emerged from cocoons stored at 5 and 10°C for 35 days consisted of only males. It is clear from the present study thatA. pyralophagus cocoons are more amenable to short-term storage. Contribution No. 285/87 of the Indian Institute of Horticultural Research, Bangalore-560 089.