Effect of the interaction between Anticarsia gemmatalis multiple nucleopolyhedrovirus and Epinotia aporema granulovirus,on A. gemmatalis (Lepidoptera: Noctuidae) larvae

The bean shoot borer Epinotia aporema Wals. (Lepidoptera: Tortricidae) and the velvet bean caterpillar Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) are key pests of soybean and other legume crops in South America. They are often found simultaneously in certain regions. A. gemmatalis nucleopolyhedrovirus (AgMNPV) is widely used to control A. gemmatalis. More recently, E. aporema granulovirus (EpapGV) has been characterized and evaluated as a bioinsecticide for E. aporema. In order to increase its potential use and to design optimized strategies for the management of lepidopteran pests, we evaluated the interaction between EpapGV and AgMNPV on third instar A. gemmatalis larvae. Larvae fed with 50 AgMNPV OBs/larva showed an increase in the mortality rates (from 42% to 81%) and a decrease in the median survival time (from 7.7 days to 5.7 days) when these OBs were mixed with 6000 EpapGV OBs/larva. When 300 AgMNPV OBs/larva were used alone or in combination with EpapGV OBs no changes in biological parameters were observed. No mortality was detected in A. gemmatalis larvae treated with EpapGV alone. In larvae fed with the viral mixtures, only AgMNPV DNA was detected by PCR. A. gemmatalis peritrophic membranes (PMs) examined by SDS–PAGE and scanning electron microscopy showed signs of damage. Notably, we found the presence of spheroidal bodies associated with damaged areas in the PMs of larvae fed with EpapGV but not in those that were given AgMNPV alone. These results show that EpapGV increases the viral potency of AgMNPV, and thus the insecticidal efficiency, suggesting that the use of formulations including both viruses might be a valuable tool for pest management.     

Biological characteristics and thermal requirements of a Brazilian strain of the parasitoid Trichogramma pretiosum reared on eggs of Pseudoplusia includens and Anticarsia gemmatalis

A new strain of the parasitoid Trichogramma pretiosum, was collected in Rio Verde County, State of Goiás, Central Brazil, and designated as T. pretiosum RV. This strain was then found to be the most effective one among several different strains of T. pretiosum tested in a parasitoid selection assay. Therefore, its biological characteristics and thermal requirements were studied, aiming at allowing its multiplication under controlled environmental conditions in the laboratory. The parasitoid was reared on eggs of Pseudoplusia includens and Anticarsia gemmatalis at different constant temperatures within an 18–32 °C temperature range. The number of annual generations of the parasitoid was also estimated at those temperatures. Results have shown that T. pretiosum RV developmental time, from egg to adult, was influenced by all temperatures tested within the range, varying from 6.8 to 20.3 days and 6.0 to 17.0 days on eggs of P. includens and A. gemmatalis, respectively. The emergence of T. pretiosum RV from eggs of A. gemmatalis was higher than 94% at all temperatures tested. When this variable was evaluated on eggs of P. includens, however, the figures were higher than that within the 18–30 °C range (more than 98%), and were also statistically higher than the emergence observed at 32 °C (90.2%). The sex ratio of the parasitoids emerged from eggs of A. gemmatalis decreased from 0.55 to 0.29 at 18–32 °C, respectively. However, for those emerged from eggs of P. includens, the sex ratio was similar (0.73, 0.72 and 0.71) at 20, 28 and 32 °C, respectively. The lower temperature threshold (Tb) and thermal constant (K) were 10.65 °C and 151.25 degree-days when the parasitoid was reared on eggs of P. includens; and 11.64 °C and 127.60 degree-days when reared on eggs of A. gemmatalis. The number of generations per month increased from 1.45 to 4.23 and from 1.49 to 4.79 when the parasitoid was reared on eggs of P. includens and A. gemmatalis, respectively, following the increases in the temperature.     

Fluorescent Brighteners Improve Anticarsia gemmatalis (Lepidoptera: Noctuidae) Nucleopolyhedrovirus (AgMNPV) Activity on AgMNPV-Susceptible and Resistant Strains of the Insect

Fluorescent (optical) brighteners are known for their characteristics of protecting baculoviruses against deactivation by ultraviolet (UV) light and enhancing the activity of these agents as microbial insecticides on hosts and semipermissive hosts. These substances were evaluated in combination with the velvetbean caterpillar, Anticarsia gemmatalis Hübner, multiple-embedded nucleopolyhedrovirus (AgMNPV). The first trial involved 4 fluorescent brighteners (Blankophor BBH, Blankophor HRS, Blankophor RKH, and Tinopal LPW) obtained from the United States. The second trial was conducted with 11 fluorescent brighteners (Tinopal UNPA-GX, Tinopal DMS, Tinopal CBS, Leukophor DUB, Leukophor BSBB, Hostalux KS-N, Hostalux ETBN, BRY 10 D2 100, BRY 10 D2 150, Uvitex BHT, and Uvitex NFW) available in Brazil in combination with the AgMNPV to determine the degree of enhancement of viral activity. These brighteners were also evaluated with regard to AgMNPV protection against deactivation by UV light. Combinations of the virus with selected fluorescent brighteners were tested against both AgMNPV-susceptible and resistant strains of A. gemmatalis. In the first trial, brighteners obtained from the United States promoted increases in AgMNPV activity from 5.2-fold (Blankophor HRS) to 76.6-fold (Blankophor RKH) and reduced the mean time to death by 2.8 to 3.5 days. In the second trial, the most effective brightener (Tinopal UNPA-GX) reduced the LC₅₀ in A. gemmatalis larvae from 7083 occlusion bodies (OBs)/ml (virus alone) to 77.8 OBs/ml (≈90-fold). When 4 selected brighteners were tested in combination with the AgMNPV in resistant insects, the LC₅₀ was reduced by ca. 10,000-fold (Leukophor DUB) to ca. 62,000-fold (Tinopal UNPA-GX), in comparison to the LC₅₀ of 3.7 × 10⁷ OBs/ml observed for the virus alone. Therefore, mortality of highly resistant A. gemmatalis larvae to the AgMNPV increased dramatically when the virus was combined with some fluorescent brighteners. UV protection measured by original activity remaining (OAR) varied from <30% OAR (Uvitex NFW) to >90% OAR (Tinopal UNPA-GX and BRY 10 D2 100). All efficacious brighteners were stilbene disulfonic acid derivatives and, when used alone, none showed negative effects against A. gemmatalis larvae.     

Effects of Fetal Bovine Serum deprivation in cell cultures on the production of <Emphasis Type="Italic">Anticarsia gemmatalis</Emphasis> Multinucleopolyhedrovirus

Background  

Anticarsia gemmatalis is a pest in South America's soybean crops, which could be controlled by the Multinucleopolyhedrovirus of A. gemmatalis (AgMNPV). Currently, its commercial production is based on infected larvae. However, the possibility of using modified baculoviruses in Integrated Pest Management programs has stimulated an interest to develop alternative multiplication processes. This study evaluated the AgMNPV production in UFL-Ag-286 cells previously deprived Fetal Bovine Serum.     

The effects of serial passage of a nucleopolyhedrosis virus through an alternate host system

The multiple-embedded velvetbean caterpillar nucleopolyhedrosis virus (VBC-NPV) ofAnticarsia gemmatalis Hübner was shown to be infectious of a variety of noctuid hosts. The mortality data demonstrated the importance of defining the dosage used in host range analysis. Serial passage of the VBC-NPV through the soybean looper,Pseudoplusia includens, was done to select for host range variants of this NPV. After several passages of the VBC-NPV through this insect the virulence of the progeny virus remained unchanged indicating heterogeneity in the host and not the virus population. However, between the 3rd and 5th serial passage throughPseudoplusia a latent NPV identical to a single-embedded NPV previously associated fromA. gemmatalis was activated. The biological and biochemical characteristics of this isolate demonstrated it to be distinct from the original VBC-NPV. A single passage of this activated virus throughA. gemmatalis resulted in the production of viral progeny having characteristics of the original VBC-NPV. Serial passage of this virus preparation throughP. includens resulted in virus progeny having biological properties associated with both the original VBC-NPV and the activated NPV isolate.     

Trichogramma pretiosum parasitism of Pseudoplusia includens and Anticarsia gemmatalis eggs at different temperatures

Egg parasitism of Trichogramma pretiosum strain RV when presented with eggs of Anticarsia gemmatalis and Pseudoplusia includens was investigated at 18, 20, 22, 25, 28, 30 and 32 °C. The number of eggs parasitized per day decreased for both hosts as a function of the age of parasitoids, reaching 80% of lifetime parasitism more rapidly as temperature increased; on the 4th day at 32 °C and on the 12th day at 18 °C. The lifetime number of parasitized P. includens eggs achieved by the parasitoid maintained at 20 °C (44.95 ± 3.94) differed from the results recorded at 32 °C (28.5 ± 1.33). Differently, the lifetime number of A. gemmatalis parasitized eggs did not differ among the temperatures. When T. pretiosum reached 100% of lifetime parasitism, each adult female had parasitized from 28.5 ± 1.33 to 44.95 ± 3.94 and from 29.58 ± 2.80 to 45.36 ± 4.50 P. includens and A. gemmatalis eggs, respectively. Also, the longevity of these adult T. pretiosum females, for which P. includens or A. gemmatalis eggs were offered, was inversely correlated with temperature. Not only were the survival curves of those adult T. pretiosum females of type I when they were presented with eggs of A. gemmatalis but also with eggs of P. includens, i.e., there was an increase in the mortality rate with time as the temperature increased. In conclusion, T. pretiosum strain RV parasitism was impacted by temperature when on both host eggs; however, the parasitoid still exhibited high survival and, more importantly, high number of parasitized A. gemmatalis and P. includens eggs even at the extremes tested temperatures of 18 and 32 °C. Those results indicate that T. pretiosum strain RV might be well adapted to this studied temperature range and, thus, be potentially suitable for use in biological control programs of P. includens and A. gemmatalis in different geographical areas that fits in this range. It is important to emphasize the results here presented are from laboratory studies and, therefore, field trials still need to be carried out in the future with this strain in order to support the full development of the technology intend to use this egg parasitoid in soybean fields worldwide.     

Inactivation of the ecdysteroid UDP-glucosyltransferase (egt) gene of Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) improves its virulence towards its insect host

Some baculovirus have been genetically modified for the inactivation of their ecdysteroid glucosyltransferase (egt) gene, and these viruses were shown to kill infected larvae more rapidly when compared to wild-type virus infections. We have previously identified, cloned, and sequenced the egt gene of Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV). Here we present data regarding the construction of an egt minus (egt−) AgMNPV and its virulence towards its insect host. We have inserted an hsp70-lacZ (3.7 kb) gene cassette into the egt gene open reading frame (ORF) and purified a recombinant AgMNPV (vAgEGTΔ-lacZ). Bioassays with third-instar A. gemmatalis larvae showed that viral occlusion body (OB) production were consistently lower from infections with vAgEGTΔ-lacZ compared to the wild-type virus. A mean of 20.4×10⁸ OBs/g/larva and 40.7×10⁸ OBs/g/larva was produced from vAgEGTΔ-lacZ and AgMNPV infections, respectively. The mean lethal concentration which killed 50% of insects in a treatment group (LC₅₀) for the 10th day after virus treatment (DAT) was 3.9-fold higher for the wild-type virus compared to vAgEGTΔ-lacZ. The recombinant virus killed A. gemmatalis larvae significantly faster (ca. 1–2.8 days), than the wild-type AgMNPV. Therefore, the vAgEGTΔ-lacZ was more efficacious for the control of A. gemmatalis larvae (in bioassays) compared to wild-type AgMNPV.     

Metarhizium rileyi biopesticide to control Spodoptera frugiperda: Stability and insecticidal activity under glasshouse conditions

The insect-pathogenic fungus Metarhizium rileyi is highly sensitive to nutritional and environmental conditions which makes it difficult to produce as a stable biopesticide. In this study, a Colombian isolate of this fungus was produced in bulk, and conidia were formulated as an emulsifiable concentrate (EC). The stability of formulated conidia was studied. Conidial viability was maintained at >85 % viability for 12 m under refrigeration and for >three months at 18 °C. The pH values were stable, while contaminant content was significantly reduced. The efficacy of the EC to control Spodoptera frugiperda (Smith) was correlated with the storage time using different mathematical models, and conservative values of six and 12 months at 8 °C and 18 °C respectively, were established. Finally, the EC was evaluated in maize plants under glasshouse conditions. The LC₅₀ and LC₉₀ were estimated to be 1.17 × 10⁴ and 4.03 × 10⁶ conidia/mL respectively and a 57 % reduction in recent damage of plants was achieved. This study demonstrated the potential of M. rileyi formulated as EC to control S. frugiperda in maize. Therefore, it is necessary to continue developing this biopesticide, in order to deliver a new tool to be integrated in pest management programs.     

Biological characteristics and thermal requirements of a Brazilian strain of the parasitoid Trichogramma pretiosum reared on eggs of Pseudoplusia includens and Anticarsia gemmatalis

A new strain of the parasitoid Trichogramma pretiosum, was collected in Rio Verde County, State of Goiás, Central Brazil, and designated as T. pretiosum RV. This strain was then found to be the most effective one among several different strains of T. pretiosum tested in a parasitoid selection assay. Therefore, its biological characteristics and thermal requirements were studied, aiming at allowing its multiplication under controlled environmental conditions in the laboratory. The parasitoid was reared on eggs of Pseudoplusia includens and Anticarsia gemmatalis at different constant temperatures within an 18–32 °C temperature range. The number of annual generations of the parasitoid was also estimated at those temperatures. Results have shown that T. pretiosum RV developmental time, from egg to adult, was influenced by all temperatures tested within the range, varying from 6.8 to 20.3 days and 6.0 to 17.0 days on eggs of P. includens and A. gemmatalis, respectively. The emergence of T. pretiosum RV from eggs of A. gemmatalis was higher than 94% at all temperatures tested. When this variable was evaluated on eggs of P. includens, however, the figures were higher than that within the 18–30 °C range (more than 98%), and were also statistically higher than the emergence observed at 32 °C (90.2%). The sex ratio of the parasitoids emerged from eggs of A. gemmatalis decreased from 0.55 to 0.29 at 18–32 °C, respectively. However, for those emerged from eggs of P. includens, the sex ratio was similar (0.73, 0.72 and 0.71) at 20, 28 and 32 °C, respectively. The lower temperature threshold (Tb) and thermal constant (K) were 10.65 °C and 151.25 degree-days when the parasitoid was reared on eggs of P. includens; and 11.64 °C and 127.60 degree-days when reared on eggs of A. gemmatalis. The number of generations per month increased from 1.45 to 4.23 and from 1.49 to 4.79 when the parasitoid was reared on eggs of P. includens and A. gemmatalis, respectively, following the increases in the temperature.     

Susceptibility of the cabbage looper, Trichoplusia ni, and the velvetbean caterpillar, Anticarsia gemmatalis, to several isolates of the entomopathogenic fungus Nomuraea rileyi

Cabbage looper larvae, Trichoplusia ni, were equally susceptible to isolates of the entomogenous fungus Nomuraea rileyi from Missouri, Mississippi, and Brazil; an isolate from Florida was 7–17 times less active than the other isolates. Velvetbean caterpillars, Anticarsia gemmatalis, were either only slightly susceptible or not susceptible to the isolates of N. rileyi from Missouri, Florida, and Mississippi. In contrast, larvae of A. gemmatalis cultured from three locations (Missouri, Florida, and Brazil) all were equally susceptible to a Brazilian isolate of N. rileyi.     

Toxicity of insecticides to Chrysodeixis includens and their direct and indirect effects on the predator Blaptostethus pallescens

The soybean looper Chrysodeixis includens (Lepidoptera: Noctuidae) is a pest of the soya bean, and increasing populations have been observed on several crops in Brazil. Control of this pest is accomplished using insecticides, particularly with new products recently launched in the market. The effectiveness of these insecticides against C. includens and their impact on natural enemies need further study. Therefore, this study aimed to determine the toxicity of nine insecticides for C. includens and their effects on the Blaptostethus pallescens. Toxicity was increased via the addition of an insecticide synergist, and behavioural changes in Blaptostethus pallescens, an anthocorid predator of C. includens, were assessed. Except for acephate, all other insecticides showed high toxicity to C. includens (mortality >80%). The estimated lethal time (LT₅₀) for C. includens was shorter for methomyl, cartap and spinosad than others six insecticides tested in this work. Chlorantraniliprole, chlorfenapyr, deltamethrin, flubendiamide, indoxacarb and spinosad showed selectivity for the predator B. pallescens and exhibited a lower toxicity to the predator than to C. includens. The detoxifying enzymes monooxygenase and glutathione S‐transferase may be involved in the selectivity mechanisms of these insecticides for the predator based on the results obtained with the synergized insecticides. Only the insecticides cartap, indoxacarb and spinosad changed the behaviour of the predator B. pallescens. These three insecticides are repellent, and the predator avoids them. However, the predator tended to remain on the surface treated with flubendiamide longer. Our results suggest that the insecticides chlorfenapyr, chlorantraniliprole, flubendiamide, spinosad and indoxacarb are the most promising compounds for use against C. includens. These compounds also preserve populations of B. pallescens and allow more sustainable integrated pest management programmes.     

Larval development and proteolytic activity of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) exposed to different soybean protease inhibitors

Anticarsia gemmatalis represents a relevant factor for lowering soybean and other legume crop productivities. Protease inhibitors affect protein degradation and reduce the availability of amino acids, impairing the development and survival of insect pests. To evaluate the possible use of proteinaceous protease inhibitors in the management of this pest, the activities of midgut proteases and the growth and development of A. gemmatalis larvae exposed to soybean Bowman–Birk trypsin-chymotrypsin inhibitor (SBBI) and soybean Kunitz trypsin inhibitor (SKTI) were determined. The survival curves obtained using Kaplan–Meier estimators indicated that SKTI and SBBI stimulated larval survival. However, the development of A. gemmatalis was delayed, and prepupal weight decreased in the presence of both inhibitors. The results showed that SKTI and SBBI inhibited the trypsin-like and total proteolytic activities of larvae on the 12th day after eclosion. On the 15th day after eclosion, larvae exposed to SKTI increased the activities of trypsin and total proteases. Although SKTI and SBBI did not affect the survival of the insect, they had effects on midgut proteases in a stage wherein A. gemmatalis fed voraciously, increased the larval cycle, and decreased prepupal weight. These findings provide baseline information about the potential of proteinaceous protease inhibitors to manage the velvetbean caterpillar, avoiding chemical pesticides.     

Use of labeled lectins to investigate cell wall surfaces of the entomogenous hyphomycete Nomuraea rileyi

Nomuraea rileyi is an entomogenous fungus infecting lepidopterous defoliators; host range of the pathogen varies according to strain. Identifying surface components of infectious stages of different strains of the fungus may be an important step in understanding host-parasite interactions. A variety of fluorescein and ferritin-conjugated lectins, including concanavalin A, peanut, soybean, winged pea and wheat germ were used to investigate surface components on germ tube and hyphal body walls from two strains (FL 74, FL 78) of N. rileyi. Binding was observed on outer wall layers when both Con A and wheat germ agglutinin conjugates were tested. There was no apparent difference in binding between the two strains or between germ tubes and hyphal bodies. These results indicate the presence of mannose (and/or glucose) residues (Con A specifity) and N-acetyl-D-glucosamine residues (wheat germ agglutinin specifity) on outer wall surfaces. Extracellular sheath material especially noticeable on germ tubes from the FL 74 strain was not labeled by any of the lectins tested, but was well stained with ruthenium red, indicating the presence of polysaccharides.Florida Agricultural Experiment Station Journal Series No. 4764.     

Susceptibility of larvae of Trichoplusia ni and Anticarsia gemmatalis to intrahemocoelic injections of conidia and blastospores of Nomuraea rileyi

The LD₅₀ for larvae of Trichoplusia ni injected with blastospores of Nomuraea rileyi was 4.30 ± 1.16 hyphal bodies/larva; the LD₅₀ for injected conidia was ca. 25,000 conidia/larva. The dose-mortality regression line for blastospores was Y = 4.6504 + 0.5487 X. Larval mortalities of Anticarsia gemmatalis and T. ni at 100 blastospores/larva were 0.4 ± 0.5% and 96.7 ± 1.9%, respectively. At a dosage of 25,000 conidia/larva, larval mortalities for A. gemmatalis and T. ni were 0.4 ± 0.5% and 43.1 ± 8.7%, respectively. Thus, larvae of A. gemmatalis were > 100 times and >200 times more resistant to injected conidia and blastospores, respectively, than were larvae of T. ni. Resistance of A. gemmatalis to N. rileyi may not be solely at the integumental barrier, as is often believed, but may also be a function of an internal physiological response.     

Classical biological control in an ephemeral crop habitat with Anticarsia gemmatalis nucleopolyhedrovirus

Anticarsia gemmatalis nucleopolyhedrovirus(AgNPV) was released as a single spray in soybean at two sites in Louisiana, near Crowley and Baton Rouge, after which viral prevalence and population density were monitored for 3--4 years. Each site had a plot with no treatment (control) and two virus-treated plots, one planted with soybean yearly for 3-4 years, and the other planted with soybean for 3-4 years except for rotation to a different crop in year 2. In year 1, the single spray ofAgNPV resulted in viral prevalence rates ranging from 25--100% A. gemmatalis mortality over the entire growing season. By the end of this season, viral accumulation in soil averaged 4.1 ×10⁴ occlusion bodies (OB)/g at Crowley and 7.4× 10³ OB/g at Baton Rouge, which had a sandier soil than Crowley. At Crowley, prevalence of AgNPVreached 49% insect mortality in the unrotated plot in year 2, and 31% in the rotated plot and 38% in the unrotated plot in year 3, in spite of moderate to low population densities of A. gemmatalis. At Baton Rouge, AgNPV prevalence decreased to peak prevalence rates of 25% insect mortality in year 2,4% in year 3, and 11% in year 4, even though A. gemmatalis population densities were moderate in years 2 and 3. Viral concentration in soil decreased to 2.7 × 10² OB/g (rotated plot) and1.4 × 10⁴ OB/g (unrotated plot) by the end of year 3 at Crowley and to 10 OB/g (rotated plot) and31 OB/g (unrotated plot) by the end of year 4 at Baton Rouge. In forward stepwise multiple regressions, the concentration of OB in soil was significantly (p = 0.0001) and positively correlated with AgNPV prevalence, but correlations of the latter parameter with host population density and rainfall were not significant (p > 0.05). Prevalence rates of the fungal entomopathogen Nomuraea rileyi were significantly (p < 0.01) and negatively correlated with AgNPV prevalence at Crowley but not in the combined data set. Prevalence of N. rileyi was negatively correlated (p = 0.0001) with precipitation and positively correlated (p = 0.0001) with A.gemmatalis population density. The research demonstrated that AgNPV can be introduced and established for long-term suppression of A.gemmatalis in an ephemeral crop habitat, but certain site-related conditions, perhaps relating to soil, are necessary for its continued success. This revised version was published online in July 2006 with corrections to the Cover Date.     

Field trials against Hoplia philanthus (Coleoptera: Scarabaeidae) with a combination of an entomopathogenic nematode and the fungus Metarhizium anisopliae CLO 53

The white grub, Hoplia philanthus Füessly (Coleoptera: Scarabaeidae), is a major pest of turf and ornamental plants in Belgium. Previously, the combination of lethal concentration of the entomopathogenic nematodes Heterorhabditis megidis or Steinernema glaseri with the entomopathogenic fungus Metarhizium anisopliae (strain CLO 53) caused additive or synergistic mortality to third-instar H. philanthus in the laboratory and greenhouse. In this present study, we examined this interaction under field conditions and compared a combination of a commercial formulation of Heterorhabditis bacteriophora (Nema-green^®) and M. anisopliae. Controls were M. anisopliae, chlorpyrifos (Dursban 5 Granules) and H. bacteriophora. Field applications (surface or subsurface) were made against a mixed population of second/third-instar H. philanthus at a sport field and lawn infested in the province of West-Flanders. In both trials, the combination of M. anisopliae with H. bacteriophora at 5 × 10¹² conidia/ha +2.5 × 10⁹ infective juveniles/ha resulted in additive or synergistic effects, causing more than 95% grub mortality when the nematodes was applied 4 weeks after the application of fungus. However, application of nematode, chlorpyrifos or fungus alone provided 39–66%, 42–60% (surface) and 33–76%, 82–100% or 37–65%, (subsurface) control of H. philanthus. We concluded that the pathogen combinations we tested are compatible elements of integrated pest management and are likely to improve control of H. philanthus larvae and perhaps other insect pests beyond what is expected from single application of the pathogen.     

Laboratory studies of the entomopathogenic fungus Nomuraea rileyi: Soil-borne contamination of soybean seedlings and dispersal of diseased larvae of Trichoplusia ni

Germinating soybean seedlings were contaminated by soil-borne conidia of the entomogenous fungus Nomuraea rileyi. Although N. rileyi was detected on the unifoliate and trifoliate leaflets, most of the inoculum was found on the cotyledons. Diseased larvae of Trichoplusia ni released on the first trifoliate leaves of soybean plants dispersed to all trifoliates and died. In this way, inoculum is produced that infects other larvae feeding on these leaves.     

Trapping noctuid moths with synthetic floral volatile lures

Male and female noctuid moths were collected from plastic bucket traps that were baited with different synthetic floral chemicals and placed in peanut fields. Traps baited with phenylacetaldehyde, benzyl acetate, and a blend of phenylacetaldehyde, benzyl acetate, and benzaldehyde collected more soybean looper moths, Pseudoplusia includens (Walker), than benzaldehyde-baited or unbaited traps. Females comprised over 67% of the moths captured and most were mated. At peak capture, over 90 male and female moths per night were collected. In another experiment, phenylacetaldehyde delivered in plastic stoppers attracted more P. includens moths than traps baited using other substrates, but this chemical delivered in wax attracted more velvetbean caterpillar moths (Anticarsia gemmatalis Hübner). Other noctuid male and female moths collected included Agrotis subterranea (F.), Argyrogramma verruca (F.), Helicoverpa zea (Boddie), and several Spodoptera species. Aculeate Hymenoptera were collected in large numbers, especially in traps baited with phenylacetaldehyde delivered from stoppers.     

Inhibition of phagocytic activity and nodulation in Galleria mellonella by the entomopathogenic fungus Nomuraea rileyi

Changes in phagocytic activity and nodulation in the greater wax moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae), were examined after treatment with the culture fluid of the entomopathogenic fungus Nomuraea rileyi SH1. When isolated hemocytes of G. mellonella were incubated with the conidia of N. rileyi in vitro, the rates of phagocytosis increased at 4 h after incubation but decreased subsequently. On the contrary, the rates of phagocytosis of isolated hemocytes decreased by 80% after 24 h preincubation with the fungal culture fluid (1/200, 1/100 dilutions). Levels of inhibition of phagocytic activity by the culture fluid depended on dilutions used. Galleria mellonella larvae showed a peak of nodulation at 4 h after injection with conidia. The percentage of nodules in hemolymph did not decrease by preinjection with the culture fluid, whereas the percentage of nodule‐containing conidia decreased, depending on the injected fluid. However, phagocytosis and nodulation in G. mellonella did not change after treatment of the culture fluid with proteinase K, indicating that the culture fluid contained proteinaceous immunosuppressive factors. Electrophoretic analysis of the culture fluid and not the fresh medium without culturing the fungus exhibited protein bands. Therefore, N. rileyi possibly secretes toxic proteins that impair cellular immune responses in G. mellonella larvae.     

Interactions between a braconid,Microplitis croceipes,and a fungus,Nomuraea rileyi,in laboratory-reared bollworm larvae

The parasite Microplitis croceipes required 1.1 days longer at 26°C to complete development in Heliothis zea larvae than was required for the fungus Nomuraea rileyi to kill the host larvae and sporulate. Host larvae parasitized by M. croceipes or infected with N. rileyi failed to complete a fifth larval molt or pupate. Of the remaining healthy larvae, one-half completed six larval stadia before popation. Larvae parasitized by M. croceipes were predisposed to infection by N. rileyi, but the fungus inhibited development of M. croceipes if host larvae were infected with N. rileyi within 1 day after parasitization.