Phosphorus-32 bioelimination by arthropod predators fed labeled eggs ofHeliothis virescens [Lep.: Noctuidae]

Adults ofGeocoris punctipes (Say),Tropiconabis capsiformis Germar,Nabis roseipennis Reuter andColeomegilla maculata (DeGeer) were confined inside petri dishes and fed phosphorus-32 (^32p)-labeledHeliothis virescens (F.) eggs. Observations of bioelimination of^32p over a 72 h period allowed derivation of equations for predicting the number ofH. virescens eggs ingested by each species. Twenty-four to 72 h after eggs were eaten, the percentages of^32p eliminated ranged from ca. 14% forG. punctipes to 42 % forT. capsiformis. Cautious use of the results will aid researchers in assessing predation on^32p labeledHeliothis. Publication N^o 5935. Mississippi Agricultural and Forestry Experiment Station, Mississippi State, MS 39762.     

Potential ofGeocoris punctipes [Hemiptera: Lygaeidae] andNabis spp. [Hemiptera: Nabidae] as predators ofEpilachna varivestis [Coleoptera: Coccinellidae]

Predation byGeocoris punctipes (Say) andNabis spp. onEpilachna varivestis Mulsant was studied in the laboratory at 26.7°C and in field cages containing soybeans. Both predator groups fed uponE. varivestis eggs, 1st, 2nd and 3rd stage larvae, but not upon 4th stage larvae, pupae, or adults. G. punctipes females produced significantly fewer eggs when fedE. varivestis eggs or 1st stage larvae than those fedGalleria mellonella (L.). Longevity of maleG. punctipes was significantly reduced when fedE. varivestis eggs; however, female longevity was not affected. Results from field cage tests indicated bothG. punctipes andNabis spp. could significantly reduce the density ofE. varivestis.     

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.     

Functional response ofChrysopa carnea [Neur: Chrysopidae] larvae feeding onHeliothis virescens [Lep.: Noctuidae] eggs on cotton in field cages

The functional response of 3rd instarChrysopa carnea (Stephens) larvae feeding on 4 densities ofHeliothis virescens (F.) eggs was determined on caged cotton (Gossypium hirsutum L.).C. carnea larvae had a mean search rate of 1.08×10⁻⁵ ha/predator-day or 0.11 row-m/predator-day.      

Predation and parasitism of cotton leafworm eggs,Alabama argillacea [Lep.: Noctuidae]

The identification and efficiency of arthropod predator and parasites related to natural control of cotton leafworm eggs,Alabama argillacea (Huebner), were studied in a cotton field, Jaboticabal, SP, Brazil. Plants were marked randomly and the eggs found on them were indicated by arrow tapes for predation and parasitism observations. To evaluate and identify the arthropod fauna in the row-meter containing the marked plant, visual countings and collections using D-Vac ® and “beat sheet” were used. The average predation rate during the season, in the presence of 23.0 predators per row-meter, was 50.6% and the parasitism byTrichogrammatoidea annulata was 44.9% totaling 95.5% of egg reduction. In decreasing order of abundance, the arthropod predators found were the antPheidole sp., the spiderChrysso clementinae Petrunkevitch, the hemipteraOrius insidiosus Say andCeratocapsus mariliensis Carvalho & Fontes, and the coccinellidHyperaspis festiva (Mulsant).     

Predation on eggs and larvae ofHeliothis virescens [Lep.: Noctuidae] by an adult predator complex in cage studies on cotton

Predation by a predator complex consisting of adults of the lygaeidGeocoris punctipes (Say), the nabidsNabis roseipennis Reuter and/orTropiconabis capsiformis Germar and the coccinelids,Hippodamia convergens Guerin-Meneville andColeomegilla maculata (DeGeer) onHeliothis virescens (F.) eggs, 1st-instar larvae or both on late pinhead square and early bloom stage cotton was evaluated in field cages in Mississippi. Prey densities of 4 (11, 512/ha) or 8 per cage and predator: prey (P:p) ratios of 1∶1, 2∶1, 3∶1, 4∶1 and 5∶1 were used. Prey were labeled with phosphorus-32 or carbon-14 to determine predator ingestion and effectiveness. Average percent egg predation as a function of P:p ratio ranged from 2.1 to 12.1 for a 48 h period. The average percent predation on larvae as a function of P:p ratio ranged from 5.3 to 22.0. The hemiptera fed more than the coleoptera on larvae, andG. punctipes was the best egg predator. For the range of predator densities used, the average area of discovery for the predator complex was 6.98 × 10⁻³ m/day and 2.34 × 10⁻² m/day when exposed to eggs and larvae, respectively. Publication N^o 5936-Mississippi Agricultural and Forestry Experiment Station, Mississippi State, MS 39762.     

Effects of parasitism byApanteles sagax [Hym.: Braconidae] on growth,food consumption and food utilization inSylepta derogata larvae [Lep.: Pyralidae]

Laboratory studies were made of the growth, food consumption and food utilization by parasitized and unparasitizedSylepta derogata (F.) larvae. Growth was lower in parasitized than in unparasitized larvae. Parasitized larvae consumed significantly less food than unparasitized larvae. The dry weightfresh weight consumption index did not differ significantly between the 2 types of larva. Parasitism increased the efficiency of digestion but had no effect on the efficiencies of conversion of ingested and digested food to body matter.

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Résumé On a étudié en laboratoire la croissance, la consommation et l'utilisation des aliments de larves deSylepta derogata (F.) parasitées ou non. La croissance est moindre chez les larves parasitées et elles consomment significativement moins de nourriture que les chenilles non parasitées. L'indice de consommation poids sec-poids frais n'est pas différent de manière significative chez les 2 catégories de larves. Le parasitisme diminue l'efficacité digestive mais n'a pas d'influence sur l'efficacité de la conversion des aliments ingérés et digérés en matières corporelles.

     

Parasitoids ofPectinophora gossypiella [Lep.: Gelechiidae] andEarias spp. [Lep.: Noctuidae] in the Punjab

Observations on the parasitoids of cotton bollworms in the Punjab were made during 1978 and 1979. The 2 trichogrammatid egg parasitoids, viz.Trichogramma achaeae Nagaraja & Nagarkatti andTrichogrammatoidea sp. nearguamensis Nagaraja (MS) were recovered fromPectinophora gossypiella (Saunders) in addition to 1 braconid egg-larval parasitoidChelonus sp. and 7 larval parasitoids, viz. 4 braconidsApanteles angaleti Muesebeck,Bracon greeni Ashsmead,Camptothlipsis sp. andRogas sp., 1 elasmid,Elasmus johnstoni Ferrière, 1 bethylid,Goniozus sp. and 1 ichneumonid,Scambus lineipes (Morley). FromEarias insulana Boisduval andEarias vittella F., 3 trichogrammatid egg parasitoids,T. achaeae, Trichogramma chilonis Ishii, andT. sp. nearguamensis 2 braconid larval parasitoids,B. greeni andRogas sp. and 1 chalcid pupal parasitoid,Brachymeria nephantidis Gahan, were recovered. One eurytomid hyperparasitoid,Eurytoma braconidis Ferrière was also recovered from the cocoons ofB. greeni. Of these parasitoids,T. achaeae, T. sp. nearguamensis, Camptothlipsis sp. andS. lineipes fromP. gossypiella, T. achaeae andB. nephantidis fromEarias spp. andE. braconidis fromB. greeni are new records.     

Acceptance of eggs ofRivula atimeta,Naranga aenescens [Lep.: Noctuidae] andHydrellia philippina [Dipt.: Ephydridae] by insect predators on rice

Eight insect predators common in the rice ecosystem in the Philippines were compared in the laboratory on their ability as to feed on the eggs of green hairy caterpillar,Rivula atimeta Swinhoe. A ranking, based on feeding rates was made:Metioche vittaticollis (Stål) (Gryllidae) was the most voracious predator, followed byAnaxipha longipennis (Serville)(Gryllidae), Ophionea nigrofasciata (Schmidt-Goebel)(Carabidae), Micraspis nr.crocea (Mulsant) (Coccinellidae) andConocephalus longipennis (de Haan) (Tettigoniidae). Also the smallCyrtorhinus lividipennis Reuter (Miridae), readily fed upon the eggs.Paederus fuscipes Curtis (Staphilinidae) andCoccinella repanda (Thunberg) (Coccinellidae) fed to a very limited extent.Metioche vittaticollis andCyrtorhinus lividipennis were also tested on eggs of green semilooper,Naranga aenescens Moore, and rice whorl maggot,Hydrellia philippina Ferino. The feeding rate ofM. vittaticollis was similar on the 3 different preys, butC. lividipennis had a higher feeding rate onN. aenescens eggs. In 1.6 m² field cages, different densities ofM. vittaticollis andO. nigrofasciata were allowed to feed on exposedR. atimeta eggs during 2 days.Metioche vittaticollis consumed 13 and 26 eggs at predator densities of 1 and 2 per cage respectively, but was not much higher at density 8. Predation byO. nigrofasciata was not significant.     

Studies onBonnetia comta [Dipt.: Tachinidae] parasitizingAgrotis ipsilon [Lep.: Noctuidae] larvae

Laboratory studies showed that 1st-instarBonnetia comta (Fallén) maggots (planidia) had a significant impact (P<0.05) on mortality of all black cutworm (BCW),Agrotis ipsilon (Hufnagel), instars, either by killing 1st- and 2nd-instar BCWs 2.3 to 9.7 days after parasitization or by producing a puparium from older host instars. Diet consumption and utilization by BCW larvae parasitized byB. comta as 4th instars were similar to those of nonparasitized larvae until 1 to 2 days before the parasitoid emerged. In a 2-year host exposure study in Iowa, it was found thatB. comta primarily parasitized released BCWs in June through September and did not seem to play a role in controlling the damaging 1st generation of BCW larvae. Techniques were developed to produce and store large numbers ofB. comta planidia.Bonnetia comta deposited large numbers of planidia on filter paper treated with a fecal supernatant. These planidia could be stored on filter paper in a covered Petri dish at 4.4°C for 5 days with minimal mortality. Preliminary field data show that planidia placed around corn seedlings infested with 4th-instar BCW larvae do parasitize the pest and reduce the hosts cutting potential.     

Parasites ofSpodoptera exigua,S. eridania [Lep.: Noctuidae] andHerpetogramma bipunctalis [Lep.: Pyralidae] collected fromAmaranthus hybridus in field corn

Three species of lepidopterous larvae were collected fromAmaranthus hybridus L. growing in field corn during 1975 and 1976 at Hastings, Florida.Spodoptera exigua (Hubner) was the predominant species in May.Spodoptera eridania (Cramer) was predominant in June andHerpetogramma bipunctalis (F.) in July and August. Nine native species of parasites, representing theBraconidae, Eulophidae, Ichneumonidae andTachinidae, emerged from these larvae.Meteorus autographae Muesebeck emerged from bothS. exigua andS. eridania. TheTachinidae, Winthemia rufopicta (Bigot),Eucelatori rubentis (Coquillett) andLespensia sp., emerged from mixtures ofS. exigua andS. eridania. Apanteles marginiventris (Cresson),Temelucha sp., andChelonus texanus Cresson emerged from bothS. exigua andH. bipunctalis larvae, andEuplectrus platyhypenae Howard andOphion sp. emerged fromS. eridania. All the species of parasites from the lepidopterous larvae that feed onAmaranthus hybridus are also reported as parasites ofS. frugiperda, a serious pest of corn. Therefore these larvae onA. hybridus may be a source of the parasites found attackingS. frugiperda.     

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.      

Influence of parasitism byEucelatoria bryani [Dip.: Tachinidae] on the consumption and utilisation of chickpea flour diet byHeliothis armigera [Lep.: Noctuidae]

Fourth and 5th instar larvae ofHeliothis armigera (Hübner) parasitised byEucelatoria bryani Sabrosky consumed significantly less chickpea flour diet than unparasitised larvae of the same age in the laboratory. Significant reduction in diet consumption, larval weight gain and frass produced at 24 and 48 h following parasitisation was observed in 5th instar host larvae. Parasitised larvae retained a greater percentage of food ingested (AD) than did the unparasitised ones. Unparasitised 5th instar larvae ofH. armigera were more efficient in converting the ingested food (ECI) and digested food (ECD) into body substance than larvae of similar age parasitised byE. bryani.     

Predation of cotton leafworm first instar larvae,Alabama argillacea [Lep.: Noctuidae]

Natural predation first instar larvae of the cotton leafworm (CLW)A. argillacea was studied in cotton fields in Jaboticabal, Sao Paulo State, Brazil, during 1986. The presence of naturally occurring arthropod predators showed a first instar larvae predation rate of 78.6 and 88.9% after 24 h and 48 h of exposure, respectively. A predator prey ratio of 1∶1 (1 CLW key predator per 1 prey/plant) maintained a level of no more than 1 CLW small larvae per plant. The most evident arthropod predators in the studied fields were: beetles (Coleoptera: Coccinellidae), antsPheidole sp. andConomyrma sp.;Dermaptera Doru lineare (Eschs);Hemiptera Geocoris sp., andOrius insidiosus Say; and the spidersTheridion volubile, Chrysso pulcherrima, Misumenops sp.,Chiracanthium sp., andOxyopes salticus Hentz.      

Control ofAgrotis segetum [Lep.: Noctuidae] root crops by granulosis virus

Agrotis segetum Schiff. granulosis virus (GV) propagated in Danish laboratory cultures was applied against field populations ofA. segetum in experimental latin square plots planted with beetroots, carrots and potatoes. Some test plots were isolated by net tents extending 15 cm into the soil whereas others were not caged. Plots were treated with suspensions of GV containing 10⁶ to 10⁸ capsules per ml with 50 ml being applied per m² of plot. In 4 tests in which released eggs or larvae were caged over plots, cutworm numbers and damage were reduced by approximately 80% compared to untreated plots. The comparable reductions in 3 open experiments with natural populations of cutworms were 65–75%. GV-treatment 4 days after release of eggs appeared to be more effective than treatment 10 days after release. Whereas treatments with 10⁷ and 10⁸ capsules per ml reduced damages to approximately 75%, the effect of 10⁶ Capsules was only 50%. Damage reduction by treatment with parathion varied from 50% in 2 caged experiments to approximately 20% in 2 open experiments, indicating that parathion was less effective than GV. The data indicated a residual effect of GV from one year to the next. Furthermore GV appeared to have spread at least 10 m from foci of application.     

Interspecific competition among endoparasitoids of tobacco budworm larvae [Lep.: Noctuidae]

The ability of female larvae endoparasitoids [Microplitis croceipes Cresson:Cardiochiles nigriceps Viereck andCumpoletis sonorensis (Carlson)] to distinguish between unparasitized tobacco budworm,Heliothis virescens (F.), larvae andH. virescens larvae parasitized by the egg-larval parasitoidChelonus insularis,Cresson, was determined in laboratory studies. The 3 species of larval endoparasitoid females did not appear capable of distinguishing between unparasitized andC. insularis parasitized larvae resulting in multiple parasitoidism. The results of the ensuing competition between the 3 species for possession of the host demonstrated that bothC. sonorensis andM. croceipes were intrinsically superior toC. insularis. Both larva endoparasitoids destroyed the olderC. insularis larvae by physically attacking the latter. The presence ofC. insularis larvae in the host was found to prevent the hatch of compeatingC. nigriceps eggs through physiological suppression. The results show that the early attack of a host, as in the egg-larval parasitoid habit, is not necessarily advantageous.     

Larviposition response ofBonnetia comta [Dipt.: Tachinidae] to a kairomone ofAgrotis ipsilon [Lep.: Noctuidae]

A kairomone in the frass and vomitus of larvae ofAgrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) triggered larviposition activity in its habitual parasitoidBonnetia comta (Fallen) (Diptera: Tachinidae). Laboratory bioassays showed that no measurable differences existed in the larviposition-stimulating activity of frass fromA. ipsilon larvae reared on 3 different food sources. In other tests, corn seedlings damaged by late-instar larvae ofA. ipsilon elicited strong larviposition activity inB. comta; other corn seedlings damaged with a razor blade did not elicit strong activity. Frass aged for 8-days was only slightly less effective at releasing a larviposition response when compared to fresh frass.B. comta was not stimulated to larviposit by oven dried frass or an India ink dot the color and shape of a fresh pellet from a host larva. The host habitat location and host finding process forB. comta and other tachinid species that deposit free-living maggots is discussed.     

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.

     

Developmental interactions between the army wormLeucania separata [Lep.: Noctuidae] and its parasiteApanteles ruficrus [Hym.: Braconidae]

The developmental interactions between the gregarious endoparasitoidApanteles ruficrus Hal. and the army worm,Leucania separata Walker were investigated. The parasitoid preferred young host larvae and developed in 9.5 days irrespective of host age at the time of parasitization. The growth of parasitized host larvae were depressed. The net maximum weight of the host larva was positively correlated with the number of parasitoid eggs laid when the 2nd instar was parasitized. And when parasitizing in 2nd instar, the weight of parasitoid was negatively correlated with the number of eggs laid. The parasitoid has an ability to regulate the size of the host and the parasitoid itself according to the number of eggs laid when the host larva is very small.     

Interference between two nuclear polyhedrosis viruses of the armyworm,Pseudaletia unipuncta [Lep.: Noctuidae]

The larva ofPseudaletia unipuncta (Haworth) is susceptible to 2 nuclear polyhedrosis viruses (NPV), the typical (TNPV) and the hypertrophy (HNPV) strains. The interference between the 2 viruses was studied primarily in the tracheal and fat tissues. When both viruses were microfed simultaneously, no larva had mixed virus infections and most were infected with TNPV. In order to obtain 50% infection by each virus the inoculum of HNPV had to be increased by 1000 polyhedra/ml at the LD₅₀ value of TNPV. Mixed infection resulted when TNPV was inoculated 1 and especially 2 days after HNPV inoculation. In mixed infection, each virus attacked certain areas of the tracheae instead of random cells. These results indicated an interference or antagonism between the 2 viruses. The possible cause for the interference is discussed.

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Résumé La larve dePseudaletia unipuncta (Haworth) est sensible à 2 virus à polyèdres nucléaires (NPV), la souche typique (TNPV) et la souche causant une hypertrophie (HNPV). L'interférence entre ces 2 virus a été étudiée essentiellement dans les trachées et le corps adipeux. Si les deux virus sont inoculés simultanément par micro ingestion aucune larve ne présente d'infection mixte et la plupart d'entre elles est infectée par le TNPV. Pour obtenir 50% d'infection par chacun des virus, l'inoculum de HNPV doit être accru de 1000 polyèdres par ml par rapport à l'inoculum provoquant la DL 50 du TNPV. Une infection mixte est enregistrée quand le TNPV est inoculé 1 jour et de préférence 2 jours après l'introduction du HNPV. Dans ce cas d'infection mixte chaque virus attaque certaines régions des trachées et non pas des cellules réparties au hasard. Ces résultats prouvent une interférence ou un antagonisme entre les 2 virus, dont la cause est discutée.

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Portion of a dissertation submitted by the senior author for the degree of doctor of philosophy from the University of California, Berkeley. Part of the study was supported by a NSF grant provided to the junior author.