Actebia Fennica Research Articles

The influence of smoke volatiles on sexual maturation and juvenile hormone biosynthesis in the black army cutworm, Actebia fennica (Lepidoptera: Noctuidae)

Outbreaks of the black army cutworm, Actebia fennica, are associated with recently burned sites, where larvae feed on early successional plants. In the present paper we show that smoke volatiles stimulate juvenile hormone biosynthesis in virgin females, resulting in a more rapid rate of oocyte maturation and a significant advance in the age of first calling (the release of the sex pheromone) compared to control females. The ecological implications of this physiological effect are discussed.

Searching Speed of Trichogramma minutum and Its Potential as a Measure of Parasitoid Quality

Abstract Searching speed has been proposed as a quality criterion for the prediction of field efficacy of mass-reared Trichogramma spp. The searching speed, walking speed, and activity of female T. minutum Riley were measured using an automated video tracking system. Two- and 3-day-old thelytokous females searched twice as fast as 1-day-old females, whereas the searching speed of a strain of arrhenotokous females was similar at all ages. When reared on Actebia fennica Tauscher, the resulting wide variation in wasp size was not related to searching speed or walking speed. Both strains of T. minutum searched faster later in the day. In a second laboratory experiment, the proportion of hosts parasitized, the proportion of hosts accepted, and searching speeds of parasitoids were measured simultaneously for groups of females of both strains. Percentage parasitism was related to host acceptance but not searching speed. Searching speed was unrelated to the estimated number of host contacts. These results suggest that searching speed is not a useful measure of parasitoid efficacy for T. minutum.

Cry9Ca1 Toxin, a Bacillus thuringiensis Insecticidal Crystal Protein with High Activity against the Spruce Budworm (Choristoneura fumiferana)

The Cry9Ca1 toxin from Bacillus thuringiensis was significantly more toxic to spruce budworm (Choristoneura fumiferana) than the Cry1Ab6, Cry1Ba1, Cry1Ca2, Cry1Da1, Cry1Ea1, and Cry1Fa2 toxins. It displayed high activity against silkworm (Bombyx mori) but was not toxic to black army cutworm (Actebia fennica) or gypsy moth (Lymantria dispar). The Cry9Ca1 is the most effective spruce budworm toxin known to date and may offer promise for control and resistance management of that species.

NEMATODE CONTROL OF BLACK ARMY CUTWORM (LEPIDOPTERA: NOCTUIDAE) UNDER LABORATORY AND FIELD CONDITIONS

AbstractFour steinernematid strains, Steinernema carpocapsae All strain, S. carpocapsae Umeå strain, S. feltiae Lie strain, and S. feltiae strain 27, were evaluated in laboratory and field tests as potential agents for the control of the black army cutworm, Actebia fennica (Tauscher). Although each of the six instars was susceptible to attack, incidences of infection were highest and generally over 60% for the third, fourth, and fifth instars when exposed to 100 infective juvenile nematodes in petri dishes. Fifth-instar larvae exposed for 1 week to soil containing 4000 infective juveniles in a 1:1:1 mixture of the L1c, All, and Umeå strains were most frequently infected with the L1c strain when reared at 10 and 12 °C and with the All strain when reared at 14 and 16 °C. One hundred thousand infective juveniles of the L1c, All, and Umeå strains and strain 27, alone and in various combinations, and applied by either a spray or soil-plug inoculation, killed black army cutworm larvae caged in the field for 1 week with treated black spruce seedlings and provided protection of current and 1 -year-old foliage. Treatments that included strain 27 provided the best protection when daily mean soil temperatures were 7–11 °C in comparison to treatments that included the Umeå or All strains, whereas treatments that included the All strain as a component appeared to be more effective than treatments containing the L1c and Umeå strains when daily mean soil temperatures were 16–17 °C.

Variation in Susceptibility of Tree-Feeding Insect Species to Photoactivated Thiophene Insecticides

The contact toxicity of the plant-derived phototoxin, alpha-terthienyl (α-terthienyl) and its cyano-derivative (CN-derivative) was examined with respect to 16 terrestrial, primarily tree-feeding insect species by topical application followed by exposure to near-UV light. The sensitivity of these species to α-terthienyl varied 500-fold. Lepidoptera larvae were sensitive, with the exception of black army cutworm. For 2 species, white marked tussock moth and spruce budworm, the material was more toxic than fenitrothion and carbaryl but less toxic than permethrin. Sawfly species varied videly in susceptibility, whereas adults of coleopteran species were tolerant. The activity of the CN-derivative was generally similar to the parent α-terthienyl to 6 lepidopteran species, in contrast to previously reported results of its higher activity to mosquito larvae.

Assessment of Trichogramma species for biological control of forest lepidopteran defoliators

AbstractIn a laboratory study, we determined the potential of three Trichogramma (Hymenoptera: Trichogrammatidae) species, T. brassicae Bezdenko, T. minutum Riley and T. nr. sibiricum Sorokina, for biological control against six species of forest lepidopteran pests, black army cutworm, hemlock looper, eastern spruce budworm, western spruce budworm, white‐marked tussock moth, and gypsy moth. Females of each parasitoid species were offered eggs from each of the six host species. Parasitization and the effect of the host species on the emerging progeny were examined and recorded. Trichogramma minutum had the broadest host range and successfully parasitized four host species out of the six offered. Trichogramma nr. sibiricum had the narrowest host range and parasitized only two species of hosts. Of the six host species, black army cutworm was the most preferred by all three Trichogramma species; white‐marked tussock moth and gypsy moth were not parasitized by any parasitoids. There was a positive correlation between the size of female offspring and their corresponding egg complement in all three parasitoid species. The developmental time of parasitoids from egg to adult was influenced by both the parasitoid and host species. Our results suggest that T. minutum has the greatest potential for biological control against various forest lepidopteran pests and that the black army cutworm may be the best target candidate for further study.

Growth inhibitory and antifeedant effects of azadirachtin on six noctuids of regional economic importance

AbstractThe comparative efficacy of azadirachtin, the major active ingredient in the botanical insecticide neem, as a larval growth inhibitor and feeding deterrent was determined for six species of noctuids of economic importance: the black army cutworm, Actebia fennica (Tausch.), the bertha armyworm, Mamestra configurata Walker, the variegated cutworm, Peridroma saucia Hubner, the zebra caterpillar, Melanchra picta (Harr.), the Asian armyworm, Spodoptera litura (Fab.), and the cabbage looper, Trichoplusia ni Hubner. When added to an artificial diet, azadirachtin inhibited neonate larval growth of all species in a dosedependent fashion. EC50 values (dietary concentration reducing larval growth by 50% relative to controls) following ten days of feeding ranged from 0.12 to 0.24 mg kg−1 but without significant differences between species. However, when second‐instar larvae were offered a choice, only larvae of P. saucia and S. litura discriminated between a control diet and diet containing azadirachtin at concentrations up to 0.4 mg kg−1. A more sensitive behavioural bioassay using fourth‐instar larvae indicated that S. litura was the most sensitive to the antifeedant effects of azadirachtin (EC50 = 1.25 ng cm−2), whereas A. fennica was the least (EC50 = 40.7 ng cm−2). Topical treatment of fourth‐instar larvae with 50 or 100 ng of azadirachtin resulted in significant inhibition of subsequent growth, diet consumption, and dietary utilization. However, A. fennica and S. litura are less inhibited that the other four species. The present study indicates that behaviourbased bioassays alone do not characterize the total effect of azadirachtin on noctuid larvae.

Mortality and height growth losses of coniferous seedlings damaged by the black army cutworm

Growth and survival of seedlings were determined for 1 to 3 years following defoliation by black army cutworm, Actebiafennica (Tausch.). Ten data sets were collected on three sites and included four species of seedlings: interior Douglas-fir, Pseudotsugamenziesii var. glauca (Beissn.) Franco; lodgepole pine, Pinuscontorta Dougl.; western larch, Larixoccidentalis Nutt.; and Engelmann spruce, Piceaengelmannii Parry. Mortality following defoliation cannot be assessed until after the flush in the next growing season because completely defoliated seedlings often regenerate new foliage and survive. More than 90% of the total mortality that did occur was detected at that time. Mortality of up to 39% occurred when seedlings were defoliated more than 60%; most of this occurred when planting was carried out concurrent with defoliation. Synergistic root stress effects caused by poor planting, dry sites, or drought significantly increased mortality. Height growth was significantly reduced when defoliation was greater than 60%; the greatest effects occurred when terminal bud destruction accompanied needle loss. Growth losses were greatest the year of defoliation; recovery of height growth of lodgepole pine was complete by the 2nd year on good growing sites. On poor sites, retardation of lodgepole pine height growth was still evident after 3 years.

Selection of pheromone trap and attractant dispenser load to monitor black army cutworm,Actebia fennica

Catch rates of black army cutworm moths,Actebia fennica (Lepidoptera: Noctuidae), were determined for different types of traps and different dispenser loads of sex attractant. Of the five traps tested, highest catch (35 males/per night) was obtained with Uni-Traps, whereas Pherocon 1CP, Delta and Hara traps rapidly became saturated at 9, 6, and 11 males/per night, respectively. Multi-Pher traps, like the Uni-Traps, have a covered vertical cone with a large collecting bucket but only catch about 1/3 of the number of moths (9 males/per night) as the Uni-Traps, thus reducing potential saturation. Red rubber septa loaded with 500 μg of attractant blend gave a consistent catch for at least 60 days; 1000 and 2000 μg loadings lasted for a minimum of 90 days. Polyvinylchloride and red rubber septa dispensers containing 100 μg of attractant had similar catch rates, which decreased rapidly with age. Based on these trap and lure-loading experiments, Multi-Pher traps baited with 1000 μg of attractant in a red rubber septum were selected for future calibration studies between catch density and population fluctuations on susceptible sites. Two years of monitoring results also are reported.

IDENTIFICATION OF SEX PHEROMONE COMPONENTS OF THE BLACK ARMY CUTWORM, ACTEBIA FENNICA (TAUSCHER) (LEPIDOPTERA: NOCTUIDAE), AND A SEX ATTRACTANT BLEND FOR ADULT MALES

AbstractThe sex pheromone components of the black army cutworm, Actebia fennica (Tauscher), were identified in abdomen-tip extracts from calling female moths. The primary pheromone component was (Z)-7-dodecenyl acetate. Although (Z)-11-tetradecenyl acetate was detectable only in trace quantities in the extracts, it was the major component in the best synthetic blend for attraction of male moths. The most effective synthetic blend was (Z)-7-dodecenyl acetate and (Z)-11-tetradecenyl acetate at a ratio of 1:20. No other component detected in the extracts increased trap capture of males when added to the two-component blend; however, (Z)-5-dodecenyl acetate, (Z)-7-dodecenol, and (Z)-9-tetradecenyl acetate reduced catches. This two-component blend will be useful for studying the habits of the adults and for population monitoring.

SUSCEPTIBILITY OF 31 SPECIES OF AGRICULTURAL INSECT PESTS TO THE ENTOMOGENOUS NEMATODESSTEINERNEMA FELTIAEANDHETERORHABDITIS BACTERIOPHORA

AbstractThe susceptibility of 31 species of agricultural insect pests representing 7 families of Lepidoptera, 3 of Diptera, and 3 of Coleoptera to the entomogenous nematodesSteinernema feltiaeFilipjev andHeterorhabditis bacteriophoraPoinar, were investigated in the laboratory. Of the 27 species found susceptible toS. feltiae, 19 are reported for the first time. Of the 21 species killed byH. bacteriophora, 15 are reported for the first time. The Lepidoptera as a group were highly susceptible to the nematodes. On the basis of larval mortality caused by the nematodes, of nematode reproduction in insect cadavers, and of the known economic importance and life histories of the test insects,S. feltiaewas judged to warrant further research as a possible biological-control agent againstEuxoa ochrogaster(Guenée),E. auxiliaris(Grote),Agrotis orthogonia(Morr.),Actebia fennica(Tauscher),Mamestra configurataWalker,Delia radicum(L.),D. antiqua(Meig.), andZygogramma exclamationis(F.).

Notes on the Black Army Cutworm, Actebia fennica (Tausch.) (Lepidoptera: Phalaenidae), a Pest of Low-Bush Blueberry in New Brunswick

The black army cutwarm, Actebia fennica (Tausch.), is the most important pest of foliage of the low-bush blueberry in New Brunswick. Although usually of minor importance, it periodically appears in outbreak proportions and destroys the entire crop in heavily infested helds. Such an outbreak occurred in Charlotte County in 1944 and 1945, when the present study was initiated.The data presented in this paper are based on insectary-reared material, supplemented where possible by field observations. Larvae were reared individually in jelly jars or waxed cardboard cups and fed daily on fresh blueberry foliage. Observations on oviposition were made possible by mating reared moths.