Chrysoteuchia Topiaria Research Articles

Response of sod webworm Chrysoteuchia topiaria Zeller (Lepidoptera: Crambidae) to endophyte infection and mycotoxin profiles of cool‐season turfgrass species grown for seed in Oregon

AbstractThe subterranean sod webworm, also known as cranberry girdler (Chrysoteuchia topiaria), is one of the most damaging insect pests in cool‐season grass grown for seed crops in Oregon. Chemical control options are limited and require irrigation or rainfall for adequate insecticide incorporation to control C. topiaria larvae. Epichloë endophytes associated with cool‐season turfgrass species and their mycotoxin profiles are well‐documented in offering plant protection against invertebrates; these fungi may offer sustainable pest management tools. Our objectives were to characterize endophyte‐mediated resistance to C. topiaria in 19 commercially available cultivars of tall fescue, perennial ryegrass, and fine fescue grown for seed in Oregon. Endophyte status (presence and viability) of fungal endophytes and their mycotoxin profiles were measured using polymerase chain reaction, and liquid chromatography‐tandem mass spectrometry, respectively. No‐choice assays were conducted in the laboratory to measure the impact of endophyte status on C. topiaria larvae in two separate no‐choice experiments. Our results suggested that increased mortality of C. topiaria larvae (R2 = 0.8526, Experiment 1; R2 = 0.6628, Experiment 2) in tall fescue cultivars was most influenced by total peramine and ergot alkaloid, and total ergoline concentrations in Experiment 1 and 2, respectively. However, no significant effect on insect mortality was found in the perennial ryegrass and fine fescue cultivars included in this study. Overall, these findings suggest a viable grass–endophyte association can be utilized as a sustainable alternative to foliar insecticides for C. topiaria management in tall fescue seed crops.

Survival of submerged larvae of cranberry girdler, Chrysoteuchia topiaria, in the laboratory

Flooding for several days in late summer or early fall is reported to control larvae of the cranberry girdler, Chrysoteuchia topiaria (Zeller) (Lepidoptera: Pyralidae), which feed on roots of cranberry, Vaccinium macrocarpon Aiton (Ericales: Ericaceae). During flooding, larvae float to the surface or remain submerged. Floating larvae are vulnerable to bird predation, but the fate of submerged larvae has not been studied. The factorially designed laboratory experiments reported here examined survival of submerged cranberry girdler larvae at water temperatures of 10, 15 or 20 °C, and flood durations of 24, 48 or 72 h. These conditions are characteristic of floods applied to western Canadian cranberry farms. In the first year of the study, more submerged larvae survived at 10 °C than at 15 or 20 °C, and more survived 24-h submersion than 48- or 72-h submersion; there was no difference between survival at 15 and 20 °C or 48- and 72-h submersion. In the second year of the study, when there were no 10 °C treatments, more submerged larvae survived at 15 than at 20 °C, and more survived 24-h submersion than 72-h submersion; survival after 48 h was not significantly different from survival after 24 or 72 h. In both years, there was no interaction effect of water temperature and duration of submersion: survival of submerged larvae decreased with longer flood durations and higher temperatures. Dissolved oxygen concentrations before submersion ranged from 5.8±0.1 to 6.3±0.2 ppm in the first year, and 5.5±0.1 to 5.7±0.1 ppm in the second. After submersion, dissolved oxygen concentrations in cups with larvae were approximately 0.5 ppm lower than in cups without larvae, suggesting that larvae continued to respire and use oxygen for some time after submersion. Results of the experiments are used to improve guidelines for flooding to control cranberry girdler larvae.

Insect pests of wild cranberry, Vaccinium macrocarpon, in Newfoundland and Labrador

Cranberry (Vaccinium macrocarpon) has been commercially developed since the late 1990's in Newfoundland and Labrador. At that time, the insect fauna of the extensive stands of native, wild cranberry was not known, although these might provide a reservoir for pests to move to commercial sites. The occurrence and distribution of cranberry-feeding insects were assessed in wild stands to help cranberry growers prepare for the insect pests they might have to manage. Adults of the cranberry fruitworm, Acrobasis vaccinii were recovered in pheromone traps and larvae found in berries. The fruitworm was common and widespread. Moths of the cranberry girdler, Chrysoteuchia topiaria were caught in pheromone traps, but larvae were not recovered from plant or soil samples. There was no evidence of the black-headed fireworm, Rhopobota naevana, the cranberry weevil, Anthonomus musculus, the red-headed flea beetle, Systena frontalis, or the cranberry tipworm, Dasineura oxycoccana, serious cranberry pests in other areas. However, larvae of the lingonberry fruitworm, Grapholita libertina, were found infesting cranberry at one site in 1998. Of the species found in this study, A. vaccinii probably represents the most serious threat to the industry.

Susceptibility of cranberry girdler to entomopathogenic nematodes

The cranberry girdler, Chrysoteuchia topiaria (Zeller) (Lepidoptera: Pyralidae), is the most important sod webworm species attacking turfgrasses in Quebec, Canada (Simard 2001). Unlike other webworms, the cranberry girdler is rarely observed on grass blades but feeds on the crowns and roots in the thatch. Biopesticides based on a nematode–bacterium complex appear to hold promise as a means of controlling turfgrass insect pests, particularly those that colonize the thatch and the first few centimetres of soil (Potter 1998), such as the cranberry girdler (Georgis and Hague 1991). Our objective was to assess the susceptibility of the cranberry girdler to entomopathogenic nematodes. In the laboratory, we determined the LC50 values for four nematode species and evaluated the effect of contact time on host mortality.

Association of Insects and Ergot (<I>Claviceps purpurea</I>) in Kentucky Bluegrass Seed Production Fields

Insects in Kentucky bluegrass seed production fields in Oregon, Idaho, and Washington were sampled just before harvest and their association with ergot conidia of Claviceps purpurea Fr. (Tul.) was evaluated during 1996-1998. A diversity of insects was observed at all three locations. The most abundant beneficial insects collected with sweep nets were Nysium spp., Nabis spp., ichneumonid wasps, and Hippodamia spp. The cranberry girdler, Chrysoteuchia topiaria (Zeller), was the only important pest on grass seed collected by sweep net. Numbers of aphids such as Sitobion avenae (F.), cicadellids and thrips such as Anaphothrips spp. and Aptinothrips spp. that were collected with all aphid sampler were below economic thresholds. Other insect groups occurred in low numbers. Noctuid moths collected in universal blacklight traps included nine species of cutworms and armyworms. Protogrotis obscura (B. & McD.) was the most common cutworm species and was present in all fields. The moth Chortodes rufostrigata (Pack.) previously reported only from wet meadows in northeast and south central Oregon was found in Kentucky bluegrass fields in central Oregon, suggesting that irrigated Kentucky bluegrass seed production fields may simulate a montane meadow habitat. Conidia of C. purpurea were found on a diversity of insects, including moths, flies, leafhoppers, and thrips. Up to 100% of moths and 75% of flies collected from some fields carried conidia of C. purpurea. No correlation between ergot honeydew present in a field and number of insects with conidia of C. purpurea was detected.

Potential of a Dried Mycelium Formulation of an Indigenous Strain of Metarhizium anisopliae Against Subterranean Pests of Cranberry

We demonstrated that a dried mycelium formulation of an indigenous strain of Metarhizium anisopliae has good potential as an effective biopesticide against the black vine weevil (BVW), Otiorhynchus sulcatus (F.), and the cranberry girdler (CG), Chrysoteuchia topiaria (Zeller). The formulation was produced at moderate sized batches scales (~ 100g product per batch) using inexpensive and easily obtainable equipment (< US$1000). Levels of conidiation were consistent among production batches and storage intervals with the product remaining viable for long time periods at 4°C, in one case for more than a year. Levels of contamination by yeasts and other benign fungi were also consistent. Fewer BVW and CG were found in small plots treated with the dried mycelium formulation than in untreated plots, but differences were not always significant. A waxmoth ( Galleria mellonella ) bait bioassay demonstrated the formulation remained viable in the soil over long time periods (> 7 months). Percentage of M. anisopliae infected waxmoth larvae was significantly affected by rate.

Potential of a Dried Rice/Mycelium Formulation of Entomopathogenic Fungi to Suppress Subterranean Pests in Small Fruits

The potential of a dried rice/mycelium formulation of three species of entomopathogenic fungi ( Metarhizium anisopliae, Beauveria bassiana and Paecilomyces farinosus ) was assessed according to five criteria: storage life, field efficacy against two subterranean pests of cranberry, persistence and efficacy against first-instar black vine weevil larvae in potted strawberry and field persistence in a cranberry bog. The number of conidia sporulated from the formulation did not decline between 4 and 20 days. In small plot field trials, the numbers of black vine weevil, Otiorhynchus sulcatus (F.), were significantly lower in plots treated with 1000 gm - 2 of formulated M. anisopliae than in untreated plots. In similar trials, the numbers of adult cranberry girdler, Chrysoteuchia topiaria (Zeller), inside emergence cages were significantly lower on plots treated with the formulated M. anisopliae than on untreated plots. The formulation suppressed first-instar black vine weevil larvae in potted strawberry regardless of the species of entomopathogenic fungus or the post-inoculation interval. M. anisopliae was periodically isolated for up to 637 days from plots in cranberry bogs treated with the formulation. In general, the dried rice/mycelium formulation may be a useful fungal mycopesticide for the management of subterranean pests of small fruits, especially if applied at high rates to areas of serious pest infestation.

Natural product analogs: Stable mimics of aldehyde pheromones

AbstractUnder field conditions, the aldehyde components of the pheromones of important lepidopteran and coleopteran pests undergo chemical transformations (oxidation, polymerization, etc.) resulting in behaviorally inactive compounds. In our search for pheromone analogs with favorable chemical and biological properties, a series of nitriles, oximes and isothiocyanates, as novel functional group mimics of some cyclic and long chain pheromones, were prepared and tested. The biological activities of these nitrogen‐containing analogs were studied by electrophysiological and field experiments with three different insect species showing the nitrile analogs to be the most potent mimics, but their activities were lower than those of the natural pheromones. Thus, a 1:1 mixture of pheromone analogs in place of the corresponding natural aldehyde components III and IV elicited dose‐dependent electroantennogram (EAG) responses of antennal preparations of the female boll weevil, Anthonomus grandis. In field trials, the nitrile analogs were poor substituents for the corresponding aldehydes. In EAG experiments with antennal preparations of males of the southwestern corn borer, Diatraea grandiosella, Z11‐16:Nitrile ((Z)‐11‐hexadecenonirile) elicited dose‐dependent responses while single neuron recording from antennal preparations of this species revealed that a neuron responsive to the pheromone component was also stimulated by the mimic Z11‐16:Nitrile. In field experiments, a 97:3 mixture of nitriles Z11‐16:Nitrile and Z9‐16:Nitrile ((Z)‐9‐hexadecenonitrile) effectively attracted males of the cranberry girdler moth, Chrysoteuchia topiaria. © 1993 Wiley‐Liss, Inc.

Use of Alternative Plant Species as a Monitoring Tool for the Cranberry Girdler (Lepidoptera: Pyralidae)

Soil-dwelling larvae of the cranberry girdler, Chrysoteuchia topiaria (Zeller), are difficult to detect even at densities causing severe damage to plantings of commercial cranberry (Vaccinium macrocarpon Ait.). This study examined plant preference of this insect as a potential monitoring tool in cranberry bogs. Girdler larvae preferred grasses to Douglas fir seedlings and to cranberry plants. Among the seven grass species evaluated, foxtail (Alopecurus pratensis L.) and red top (Agrostis alba L.) were most heavily infested. Preference in these experiments is expressed as movement of larvae to these plants rather than as oviposition preference by adult females. Foxtail is suggested as a useful monitoring tool in cranberry bogs because detecting girdler larvae on this plant is easy even at very low levels of girdler infestation on cranberry plants. It is suggested that this method of attracting and monitoring also be incorporated in the protocol of experimental studies of control measures for this insect, or as a potential trap crop.

Effect of Dosage and Ratio of Sex Pheromone Components on Behavior of Chrysoteuchia topiaria (Zeller) (Lepidoptera: Pyralidae)

When the dosage of the primary pheromone component (Z)-ll-hexedecenal (Zll-16:AI) of the cranberry girdler, Chrysoteuchia topiaria (Zeller), was varied from 0.03 to 10 mg in field tests, maximum catch was obtained at a dosage of less than 1 mg. When (Z)-9-hexadecenal (Z9-16:AI)was present at 0.3, 1, or 3% of Zll-16:AI, trap catch was proportional to the logarithm of the dosage over the same concentration range. The amount of Z9-16:Althat produced maximum trap catches within calculated confidence limits of each dosage ranged from 0.2 to 2.1% when the dosages of Zll-16:Al were 0.3, 1,3, and 10 mg. Z9-16:AI at 1% always was included within the confidence limits of these dosages. The two higher dosages captured significantly more males than the two lower dosages, but trap catches were not significantly different between dosages of 0.3–1 and 3–10 mg. The reduced trap catch by Zll-16:AI alone for dosages above 1 mg was the result of the absence of an important pheromone component. In flight tunnel studies, Zll-16:AI induced limited plume-oriented flight (19% of tested males) at a dosage of 0.03 mg only, and males did not reach the source. The percentage of males exhibiting upwind flight in the plume increased dramatically when Z9-16:AI was present. At a dosage of 0.3 mg, upwind flight in the plume was 0% for the single component and 90% for the two components. Maximum upwind flight occurred at dosages from 0.03 to 3 mg and, as occurred in field tests, the Z9-16:AI at 1% of Zll-16:AI always was included within the calculated confidence limits for these dosages. The 3-mg dosage of Zll-16:AI reduced the number of males landing on the septa.

Management Practices for Cranberry Girdler (Lepidoptera: Pyralidae) in Douglas-Fir Nursery Stock1

The cranberry girdler, Chrysoteuchia topiaria (Zeller), was shown to be a pest of Douglas-fir seedlings, Pseudotsuga menziesii (Mirb.) Franco, grown in nurseries. The girdler was capable of reproduction in nursery beds where feeding larvae partially or completely girdled the taproot of seedlings. Pheromone traps indicated that grasslands bordering nurseries and not nursery beds were the primary source of adults. In addition to Douglas-fir, several species of true-fir were damaged by larvae, but no feeding damage was observed on pine, cedar, hemlock, or spruce. Insecticides applied to control adults and larvae effectively reduced the incidence of damage. When possible, a pest management program should include grasslands bordering the nursery, control of grass weeds, and use of a nonhost cover crop in the nursery.

Synergism of the Sex Pheromone of the Cranberry Girdler123

In field tests, traps baited with 1000 μg of (Z) -11-hexadecenal (the known pheromone component) and 25–50 μg of (Z) -9-hexadecenal captured 6 times as many male Chrysoteuchia topiaria as did traps baited only with 1000 μg of (Z) -11-hexadecenal.

Field Tests with the Sex Pheromone of the Cranberry Girdler 123

In 4 out of 5 tests in commercial grass seed fields, traps baited with 800, 900, or 1000 μg of (Z)-11-hexadecenal were as attractive to male Chrysoteuchia topiaria (Zeller) as traps baited with virgin females. The aldehyde was effective in attracting maximum numbers of males only within a narrow range of concentrations; a concentration of 1000 μg/septum was optimum. (Z)-9-tetradecen-1-ol formate, which has a molecular shape similar to that of the aldehyde, was not attractive to males at the concentrations tested. Varying amounts of ( E )-11-hexadecenal in combination with (Z)-11-hexadecenal did not significantly affect trap catches. The Z isomers of 13-hexadecenal, 13-octadecenal, and 11-hexadecen-1-ol proved to be potent inhibitors and interfered with normal pheromone communication.

Emergence Rhythm in Chrysoteuchia topiaria123

A laboratory study of the influence of various combinations of light, dark, and temperature on adult Chrysoteuchia topiaria (Zeller) revealed that the rhythm of emergence was exogenous and was initiated by changes of temperature or by the transition from dark to light corresponding to dawn in nature. Thus, the time of emergence in nature is probably determined by an interaction of photoperiod and temperature. In a field test, virgin females were attractive to males in a rhythmic manner whereby 71% of the males were attracted to the females between 0700 and 1100. Cool and cloudy weather reduced the number of responding males.

Hatching of Sod Webworm Eggs in Relation to Low Temperatures1

Eggs of Chrysoteuchia topiaria (Zeller), Crambus pascuellus floridus (Zeller), and Pediasia trisecta (Walker) were exposed to temperatures of 25, 15, 10, 4, and 10°C. Only those of P. trisecta hatched after exposure to 4°C for 30 days, while none hatched after exposure to –10°C. Eggs of none of the species hatched after exposure to 4 and 10°C for 60 days. Pre-exposure and postexposure conditioning had no significant effect on percent hatch of P. trisecta eggs, while length of exposure period had a significant effect.

Sod webworms and other lawn pests in California

does not appear. First page follows. Introduction After the summer of 1929, various publications began to record widespread damage to lawns and golf courses by certain species of the pyralid genus Crambus. In 1931, outbreaks of unprecedented magnitude occurred in many states, and the sod webworms, more popularly known as lawn moths, became recognized as major lawn pests. In California, sod webworms have been reported as causing more or less severe injury every year since 1929. The damage to private lawns, parks, and golf greens cannot well be evaluated in money. Undoubtedly, hundreds of thousands of dollars have been expended in this state in controlling this pest and replacing the injured grass. Lacking accurate information on lawn insects in California, pest-control operators have failed to agree on control practices. The author, accordingly, studied the subject from the fall of 1938 through 1941 in order to summarize the existing knowledge of such pests, present new biological data, and suggest practical means of control. Economic History of Sod Webworms The genus Crambus is practically world-wide in distribution and many of its species are recognized as agricultural pests. Crambus species have injured lawns and rice in Mauritius, pasture in Norway and England, sugar cane in Queensland, and rice in Brazil. In North America about 100 species are known, and some had attacked corn, oats, wheat, and pasture land as early as 1850. By 1895 the cranberry girdler, C. horiuellus (Hbn.) was a problem along the Atlantic seaboard. A few years later the corn root webworm, C. caliginosellus Clem. became a prominent pest. of tobacco. Although (Felt (1894))3 pointed out that the members of the genus Crambus are predominantly grass feeders, their injury to pasture received only an occasional comment till the publication of G. G. Ainslee’s studies beginning in 1917.