Velvetbean Caterpillar Larvae Research Articles

Production of the Anticarsia gemmatalis multiple nucleopolyhedrovirus in serum-free suspension cultures of the saUFL-AG-286 cell line in stirred reactor and airlift reactor

The velvetbean caterpillar, Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), is one of the main plagues for soybean crops. Velvetbean caterpillar larvae are susceptible to be infected by occlusion bodies of the baculovirus Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV), a biological insecticide. The insect cell line saUFL-AG-286 produces very high yields of occlusion bodies of AgMNPV in suspension cultures done in the low-cost serum-free medium UNL-10 in shake-flasks. However, its ability to adapt to conditions of industrial production in bioreactors was unknown. The aim of this study was to characterize the growth of saUFL-AG-286 cell cultures in UNL-10 medium, as well as its capability to replicate AgMNPV in two different bio-reactors at laboratory scale. The cell line was able to adapt to conditions that can be used at industrial scale, both in an airlift reactor and a stirred reactor, although the former was better than the last to support the cell growth. The infection with AgMNPV in the airlift reactor produced a high yield of occlusion bodies, with very low production of budded virus, the progeny used as inoculums. On the other hand, infection in the stirred reactor yielded high titers of budded virus. These results suggest that a feasible strategy for scaling-up the production of AgMNPV might involve the use of airlift reactors for the scaling-up of cell suspension cultures and the final production of occlusion bodies, while the scaling-up of the viral inoculums being carried out under conditions as those existing in stirred reactors.

Peanut Fungicides: Effect on Survival and Development of the Corn Earworm, Fall Armyworm, and Velvetbean Caterpillar1

Abstract The fungicides chlorothalonil, tebuconazole, and propiconazole commonly used for control of peanut diseases were evaluated for activity against the corn earworm [Helicoverpa zea (Boddie)], fall armyworm [Spodoptera frugiperda (J. E. Smith)], and velvetbean caterpillar (Anticarsia gemmatalis Hübner). Chlorothalonil most adversely affected early establishment and survival of neonates of all three insect species on peanut terminal buds. Chlorothalonil also decreased the weight of larvae of all three species at 10 d and extended the time to pupation for fall armyworm and velvetbean caterpillar larvae. Similarly, tebuconazole adversely affected early survival and establishment, decreased 10-d weight and extended time to pupation of corn earworm and velvetbean caterpillar larvae, but had little effect on fall armyworm larvae. Propiconazole had no effect on establishment and survival of corn earworm and fall armyworm larvae on peanut terminals, and actually increased the weight of 10-d-old larvae for all three insects over that recorded for the untreated control. Orthogonal comparisons of the activity of five chlorothalonil-based fungicides against the fall army-worm showed that the activity was due to chlorothalonil rather than to formulation. At equivalent concentrations used in the field, Bravo Ultrex® was significantly more active against larvae of the fall armyworm than was a comparable concentration of Bravo 72®. However, regression lines did not differ for the two fungicides for any of the developmental parameters measured when larvae of all three species were fed different concentrations of Bravo 720® and Bravo Ultrex® in their meridic diet.

Soybean Pubescence and Its Influence on Larval Development and Oviposition Preference of Lepidopterous Insects

Lepidopterous insects often cause serious economic damage to soybean, Glycine max (L.) Merr. One possible source of resistance to these pests is plant pubescence. To determine the effects of pubescence on the larval stages of corn earworm (CEW), Helicoverpa zea (Boddie), velvetbean caterpillar (VBC), Anticarsia gemmatalis Hübner, and soybean looper (SBL), Pseudoplusia includens (Walker), they were reared on foliage of ‘Tracy‐M’ lines isogenic for dense, normal, or glabrous pubescence. In addition, SBL was reared on foliage of ‘Davis’ lines isogenic for the same characters. To determine the effect of pubescence on oviposition preference and on subsequent larval defoliation levels, SBL and VBC imagoes were allowed to oviposit, under free choice conditions, on Tracy‐M lines isogenic for dense, normal, and glabrous pubescence type. In all instances, larval growth and development were significantly (P ≤ 0.05) reduced and oviposition preference was significantly increased by the presence of plant pubescence. Corn earworm larvae were more affected by pubescence than SBL or VBC larvae, as exhibited by a greater increase in larval development time and a greater decrease in pupal weight when reared on normal and dense isolines. No differences were noted in VBC and SBL growth and development on normal vs. dense isolines. In one environment, SBL deposited significantly more eggs on dense plants than on normal plants. Larval populations of both SBL and VBC produced a significantly higher level of defoliation on normal and dense isolines than on the glabrous isoline. These results show that pubescence of soybean, when compared with plants without pubescence, functions as a resistance mechanism to the larval stage of lepidopterous defoliators but enhances adult oviposition. Under free‐choice conditions, the level of increased larval damage due to the superior food substrate of glabrous plants is more than offset by the reduction in oviposition on these plants.

Evaluation of Insecticides for Insect Control in Alabama Soybeans, 1990

Abstract This field test was conducted in conventionally planted and tilled soybeans at the Plant Breeding Unit of Auburn University, Tallassee, Ala. Four replicates of 15 treatments and an untreated control were planted in a randomized complete block design. Each 0.014-acre plot was 4 rows wide (36-inch row spacing) and 50-ft long. Plots were separated by 2 border rows of soybeans and replicates were separated by a 25-ft mowed alley. Treatments were applied on 21 Sep using a tractor-mounted boom sprayer equipped with 2, TX-3 hollow cone nozzles/row operating at 40 psi and delivering 6 gal/acre. A sweep net was used to sample velvetbean caterpillar larvae. Larvae were classified as small (instar 1-2), medium (instar 3-4), or large (5 + ); they were then counted and recorded. Then sweeps per plot were taken prior to treatment and 20 sweeps/plot were taken at 3 and 6 DAT.

Arthropod Predators of Velvetbean Caterpillar, Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), Eggs and Larvae

Arthropod predators of velvetbean caterpillar, Anticarsia gemmatalis Hubner, eggs and larvae were determined using a direct observation technique. Observations of predation events were made on soybean foliage and the ground below the foliage. Predation on eggs and three size classes of larvae is presented as proportional seasonal consumption over 14 to 16 h by each arthropod predator species. On the foliage, Spanogonicus albofasciatus (Reuter) (Hemiptera: Miridae) and Geocoris punctipes (Say) (Hemiptera: Lygaeidae) were observed eating velvetbean caterpillar eggs in 1981. For small velvetbean caterpillar larvae, Tropiconabis capsiformis (Germar) (Hemiptera: Nabidae) was the major consumer in 1981, whereas in 1982, G. punctipes and Calleida decora (F.) (Coleoptera: Carabidae) were the major consumers. For medium and large velvetbean caterpillar larvae in 1981, tettigoniids (Orthoptera) consumed the largest proportion. On the ground, the ant Pheidole morrisi Forel (Hymenoptera: Formicidae) was the major consumer of all three size classes of velvetbean caterpillar larvae in 1981. In 1982, the earwig Labidura riparia (Pallas) (Dermaptera: Labiduridae) ate the greatest proportion of small velvetbean caterpillar larvae on the ground.

Discrete and Interactive Effects of Plant Resistance and Nuclear Polyhedrosis Viruses for Suppression of Soybean Looper and Velvetbean Caterpillar (Lepidoptera: Noctuidae) on Soybean

Laboratory and fieid tests with two nuclear polyhedrosis viruses (NPV) infective to the soybean looper (SBL), Pseudoplusia includens (Walker), and velvetbean caterpillar (VBC), Anticarsia gemmatalis Hübner, were conducted to investigate the effects of their integration with resistant host plants for suppression of SBL and VBC on soybean, Glycine max (L.) Merrill. The soybean genotypes were an insect resistant soybean breeding line GatIR 81-296 and a susceptible cultivar (‘GaSoy 17’). In the laboratory study, foliage consumption of late-ins tar SBL reared on the resistant genotype was severely inhibited, but VBC foliage consumption was not different on the two genotypes. NPV-infected larvae of both species consumed significantly less foliage when reared on the resistant genotype than on the susceptible genotype. Although total numbers of SBL and VBC larvae generally were not significantly lower in field plots of the resistant genotype, numbers of medium-sized VBC and large SBL larvae were significantly reduced on the resistant genotype during times of peak population density. An application of VBC NPV reduced total numbers of VBC larvae by 76% (‘GaSoy 17’ plots) and 72% (81-296 plots) at 7 d after application. SBL NPV appeared to work more slowly against host larvae; however, total numbers of SBL larvae were suppressed by 78% (‘GaSoy 17’ plots) and 76% (81-296 plots) by 14 d after application. Both pathogens were effective in reducing numbers of host larvae and percentage of defoliation in plots of resistant or susceptible soybean.

Nymphal Performance of Geocoris punctipes (Hemiptera: Lygaeidae) on Pest-resistant Soybeans

Performance of Geocoris punctipes (Say) nymphs was studied on the pest-resistant soybean, Glycine max (L.) Merrill, genotypes PI 171451 and PI 229358, and pest-susceptible ‘Bragg’ and ‘Govan’. G. punctipes nymphal growth rate decreased when the insect food was velvetbean caterpillar (VBC), Anticarsia gemmatalis Hubner, reared on ‘Bragg’, PI 229358, or PI 171451. Mortality of nymphs increased when they fed on PI 171451- or PI 229358-reared VBC larvae. Direct effects of plant food as detached leaflets included increased nymphal development time and increased nymphal mortality. Development time of nymphs was increased on a diet that included PI 171451 leaf and PI 171451- reared soybean looper, Pseudoplusia includens (Walker)

Control of Small, Medium, and Large Velvetbean Caterpillars, Total Soybean Loopers, and Total Green Cloverworms on Soybeans in Alabama, 1983

Abstract This field test was conducted on soybeans planted at the Auburn University Wiregrass Agric. Exp. Substn. at Headland, Ala. Nine treatments and an untreated check were replicated four times in a randomized complete block design. Each 0.012 acre plot was four rows wide (40-in. row spacing) and 40 ft long. Treatments were applied on 16 Sept. with a tractor-mounted boom sprayer equipped with one control droplet applicator nozzle per row adjusted to produce approximately 150 micron droplets. Spray pressure was 20 lb/in2 and the sprayer was delivering 1.6 gal/acre. Each of three insecticides (Ambush, Cymbush, and DPX 5249, a more oil-soluble formulation of Lannate) were applied alone, with soybean oil, and with Agridex. Agitation was achieved with recirculation of the insecticide solution. Insect populations were sampled by placing a standard 3-ft beat sheet between the rows and beating the plants on both sides. Larvae were identified and recorded; velvetbean caterpillar larvae were separated into small (instars 1 to 2), medium (instars 3 to 4), and large (instars 5 +) larvae. F6ur samples from each plot were taken 3, 7, and 11 days postspray (19, 23, and 27 Sept.)

Estimating Rates of Arthropod Predation on Velvetbean Caterpillar Larvae in Soybeans

A method is presented for partitioning estimates of total larval mortality into that attributable to arthropod predators and that attributable to other factors. Mark-release-recapture and direct observation techniques are used in combination to derive estimates of mortality inflicted by all predators and to identify the predator species responsible for the mortalities on small and medium larvae. Daily rates of arthropod predation on velvetbean caterpillar, Anticarsia gemmatalis Hubner, larvae ranged from 0-25% per day for small larvae and 0-73% per day for medium larvae in 2 soybean fields. Nabids consumed the greatest proportion of small and medium larvae in one field, whereas imported fire ants, Solenopsis invicta Buren, were the major consumer of small and medium larvae in the other field. Results demonstrate that the total mortality inflicted by all predators can be the same for predator complexes with different species composition.

Estimation of Absolute Larval Densities and Calibration of Relative Sampling Methods for Velvetbean Caterpillar, Anticarsia gemmatalis (Hübner) in Soybean

Two methods for estimating absolute densities of three size classes of velvetbean caterpillar, Anticarsia gemmatalis (Hubner) (Lepidoptera: Noctuidae), larvae in soybean fields are described and evaluated. These absolute-density estimation methods, sweep-net and ground-cloth, were used to sample field populations of velvetbean caterpillar larvae in soybean. These data were used to derive equations converting sweep-net and ground-cloth larval density estimates to absolute-density estimates. Calibration equations for converting sweep-net estimates to ground-cloth estimates are also presented.

Consumption and Development of Velvetbean Caterpillar 1 as Influenced by Soybean Phenology 2

Effects of soybean, Glycine max (L.) cv. Bragg, phenology on leaf consumption and development of the velvetbean caterpillar (VBC), Anticarsia gemmatalis Hubner, were investigated at 26.7 ± 1° C, 14L:10D photoperiod, and RH > 80%. Soybean plant stages were designated as early vegetative (V2–V5), late vegetative (V5–V8), flowering (R1–R2), pod set to pod fill (R4–R6), and senescent (R7–R8). Mean leaf fresh weight consumed by 4th- and 5th-instar VBC larvae declined as plant phenology progressed. Dry-weight consumption did not tend to decline with plant phenology and was more uniform for all plant growth stages than the freshweight values. Mean larval development time varied from 12.6 to 14.3 days, and mean time from egg hatch to adult varied from 21.9 to 23.4 days when larvae were fed late-vegatative and senescent foliage, respectively. Larvae fed senescent leaves produced pupae with reduced weight. Sex ratio (male/female) varied from 0.83 (flowering stage) to 1.37 (late-vegetative stage).

Control of the Velvetbean Caterpillar by Nuclear Polyhedrosis Virus and Insecticides and Impact of Treatments on the Natural Incidence of the Entomopathogenic Fungus Nomuraea rileyi1

Different concentrations of nuclear polyhedrosis virus (NPV) and insecticides (carbaryl and methomyl) were applied to natural infestations of the velvetbean caterpillar (VBC), Anticarsia gemmatalis Hubner, on soybean. Their efficacy in reducing VBC larval populations and their effect on naturally occurring epizootics of the entomogenous fungus Nomuraea rileyi (Farlow) Samson were determined. Persistence of the virus in the field was measured. Virus application rates of 75, 145, and 287.5 larval equivalents (LE)/ha suppressed VBC populations below damaging levels. Most virus-induced mortality occurred at 6, 7, and 8 days after spraying. The virus retained 65 to 70% of its original pathogenicity 7 days after treatment and 25 to 35% at 10 days. All virus doses greatly reduced the magnitude of a N. rileyi epizootic. Carbaryl or methomyl applied once at 0.28 or 0.07 kg AI/ha effectively suppressed VBC populations below economic levels for the remainder of the season. High concentrations of insecticides reduced the impact of N. rileyi by reducing the natural substrate, VBC larvae.

Velvetbean Caterpillar Ld*Jq Studies, 1973

Abstract Twelve insecticides were tested against the velvetbean caterpillar. Four to six treatment rates plus a solvent-treated check were included for each insecticide tested. A 50% acetone-water mixture was used to dissolve and dilute technical grade carbaryl and acephate to the desired concentrations. Solutions of other chemicals were prepared by dissolving and diluting technical grade materials with pure acetone. All treatments were administered with a rmcroapplicator (Isco, Model M). Test insects from an established laboratory culture of velvetbean caterpillar were used. Larbae were supplied with fresh soybean leaves daily. Last-Instar velvetbean caterpillar larvae were apportioned randomly into groups of 10. Groups were weighed collectively, and the mean weight of larvae of each group was used to determine dosages of insecticides. Individuals were topically treated with 1 u! of solution applied to the thoracic dorsum. After treatment, larvae were placed in 236 ml screen-topped cardboard cups with fresh soybean leaves. These cups were then returned to the rearing room with 25�C, 50% RH, 12/12 h light/dark phoroperiod. Mortality counts were made 24 h after treatment. The method of Litchfield and Wilcoxon (1949) was used to calculate dosage-mortality curves and LD5Q values (expressed as ug of roxicant/g of insect).

The infectivity of a nuclear polyhedrosis virus of the velvetbean caterpillar for eight noctuid hosts

Eight species of noctuid larvae were tested for susceptibility to a nuclear polyhedrosis virus of the velvetbean caterpillar, Anticarsia gemmatalis. Velvetbean caterpillar larvae were highly susceptible to crude preparations of polyhedral inclusion bodies (PIBs; LD 50 = 4.7 PIBs/larva), but preparations of purified polyhedra were much less effective against these larvae (LD 50 = 319.7 PIBs/larva). Of seven other noctuid species tested, only Heliothis virescens was as susceptible to the virus as A. gemmatalis. High dosages were required to kill Heliothis zea, Trichoplusia ni, Pseudoplusia includens, and Spodoptera ornithogalli. Plathypena scabra and Spodoptera frugiperda were not susceptible.

Winter Survival and Hosts of the Velvetbean Caterpillar in Florida

Velvetbean caterpillar larvae, Anticarsia gemmatalis Hubner, were collected throughout the winter at Homestead, Lake Worth, Ruskin, and Bartow, Florida. Year-round oviposition and larval development are indicated in South and Central Florida. Larvae were collected as late as March at Turtle Mound and Anclote in Central Florida, but were scarce, and the populations may not have survived the winter in these areas. No larvae were collected after Dec. or Jan. at Sanford, Yankeetown, and Gainesville, Florida; thus, velvetbean caterpillar populations did not appear to survive the winter in Northcentral Florida. Velvetbean caterpillars were found most frequently on the following winter hosts: Vigna luteola (Jacq.), Phaseolus lathyroides L., Dolichos lablab L. (hyacinth bean), and Pueraria lobata (Willd.) (kudzu). They were also found on the following plants: Indigofera hirusta L., Desmodium floridanum Chapm., Galactia spiciformis Torr & Gray, Rhynchosia minima (L.), Pachyrizus erosus (L.), Canavalia miritima (Aub.), and Phaseolus speciosus H. B. K.

A Nuclear Polyhedrosis Virus of Anticarsia gemmatalis: I. Ultrastructure, Replication, and Pathogenicity

A nuclear polyhedrosis virus (NPV) isolated from the velvetbean caterpillar (VBC), Anticarsia gemmatalis Hubner, on soybean in Brazil is described. The virus is a multiple embedded virus (MEV) type of the baculovirus group, with symptoms, histology, ultrastructure, and mechanism of replication similar to other reported NPVs. Velvetbean caterpillar larvae are highly susceptible to the NPV. Susceptibility studies were negative for Trichoplusia ni (Hubner), Pseudoplusia includens (Walker), and Spodoptera frugiperda (J. E. Smith); however, Heliothis zea (Boddie) was susceptible. The potential role of the NPV in an integrated pest management program for the VBC on soybean is discussed.