Mamestra Configurata Wlk Research Articles

ISOLATION, CHARACTERIZATION, AND CULTURE OFBACILLUS THURINGIENSISFROM SOIL AND DUST FROM GRAIN STORAGE BINS AND THEIR TOXICITY FORMAMESTRA CONFIGURATA(LEPIDOPTERA: NOCTUIDAE)

AbstractOne hundred and twoBacillus thuringiensisBerliner strains isolated from six different types of Canadian soil and dust from different grain storage bins were cultured in shake flasks containing Great Northern White Bean (GNWB) protein concentrate (48.6% protein) as the main nitrogen source and dextrose as the main carbohydrate source. The resulting endotoxins were bioassayed against the bertha armyworm,Mamestra configurataWlk. Thirty-three percent of soil and 66% of grain dust samples were positive forB. thuringiensis. The bacterium was found most frequently in organic-rich soil. The four most toxic soil isolates (which were seven to 15 times more toxic than the international standard, HD1-S-1980), and two nontoxic grain dust isolates were characterized by serological typing, biochemical analysis, carbohydrate utilization, plasmid profile analysis, protein profile analysis using sodium dodecyl sulfate – polyacrylamide gels, and polymerase chain reaction. Four isolates were determined to be subsp.kurstakicontaining 130–140 and 63–65 kDa proteins, and two isolates (tested for comparison) were subsp.canadensiscontaining 31 and 38 kDa proteins. Nonpyramidal-crystal-producing strains did not grow well in culture media containing GNWB, degossypellized cotton seed meal (61% protein), defatted soy flour (55% protein), or peptone as nitrogen sources. Excess of GNWB protein concentrate in shake flask culture media (30 g/L) inhibited bacterial growth and reduced the toxicity of isolate A1.2/72 subsp.kurstaki, which was the most toxic soil isolate. Isolate A1.2/72, which was 15 times more toxic for bertha armyworm larvae than the international standard (HD1-S-1980), contained threecry1Agenes (cry1Aa,cry1Ab, and cry1Ac), whereas HD-1 lacked thecry1Abgene. This strain was synergistic with strain HD-551 subsp.kenyae(cry1A,cry2A, andcry1Bgenes) but not with HD-133 subsp.aizawai(cry1Ab,cry1B,cry1C, andcry1Dgenes) when the strains were cultured together in a cotton seed meal medium and fed toM. configurata. The growth rate, economic yield, and toxicity of the new isolate, A1.2/72, produced in a 14-L laboratory fermenter declined when the fermentation ingredients were tripled. We believe that the indigenous strain A1.2/72 warrants further research development for bertha armyworm control.

Will low-glucosinolate cultivars of the mustards Brassica juncea and Sinapis alba be vulnerable to insect pests?

Foliar concentrations of the predominant glucosinolates in the mustards B. juncea (allyl glucosinolate, sinigrin) and S. alba (p-hydroxybenzyl glucosinolate, sinalbin) were determined in lines that had been selected in breeding programs for low levels of glucosinolates in their seeds for the oilseed market. The glucosinolate concentrations found in the cotyledons and leaves of the selected lines were also low, often by three or more orders of magnitude, compared with the unselected parent. The flea beetle, Phyllotreta cruciferae Goeze, and the diamondback moth, Plutella xylostella (L.), (both crucifer specialists) fed at equal rates on B. juncea and its low-glucosinolate lines, indicating that these species are insensitive to sinigrin and suggesting that their pest status on low-glucosinolate lines of B. juncea will likely remain unchanged. By contrast, the bertha armyworm, Mamestra configurata Wlk. (a generalist) fed up to fivefold more on the leaves of low-glucosinolate lines, suggesting that its pest status on low-glucosinolate B. juncea is likely to worsen relative to the mustard B. juncea. Flea beetles, diamondback moth, and the bertha armyworm fed at equal rates on the mustard S. alba and a low-glucosinolate line indicating that the status of these pests on low-glucosinolate S. alba will unlikely be much different from the mustard S. alba.Lines of S. alba differing in their sinalbin concentration by 1000-fold had equal levels of antixenosis resistance in their cotyledons against flea beetles, leaving little doubt that this resistance is independent of glucosinolates. Flea beetle resistance was also detected in the cotyledons of a low-glucosinolate line of B. juncea. The resistance was not detected in the parental line or in another low-glucosinolate line and appears to have arisen fortuitously during crossing and selection. Since resistance occurs in a line with concentrations of sinigrin three or more orders of magnitude lower than non-resistant lines, this resistance is also unlikely to be glucosinolate based. The mustards S. alba and B. juncea are a useful source of cotyledon resistance against flea beetles that is compatible with the aims of oilseed breeding. Key words: Glucosinolate, Brassica juncea, Sinapis alba, Phyllotreta cruciferae, Plutella xylostella, Mamestra configurata, resistance, mustard, canola, insect

EFFECTIVENESS OF STEINERNEMATID AND HETERORHABDITID NEMATODES AGAINST NOCTUID, PYRALID, AND GEOMETRID SPECIES IN SOIL

AbstractLarvae of one pyralid, five noctuid, and one geometrid species were exposed to six species/strains of steinernematid and two species of heterorhabditid nematodes applied to soil surface in the laboratory. The most parasitic nematodes were Steinernema bibionis Bovien for the wax moth (Galleria mellonella L.) and the bertha armyworm (Mamestra configurata Wlk.), Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) for the cereal armyworm [Pseudaletia unipuncta (Haw)], S. feltiae Filipjev Mexican for the variegated cutworm [Peridroma saucia (Hbn.)], and S. feltiae All for the red-backed cutworm [Euxoa ochrogaster (Gwen)] and the spring cankerworm [Paleacrita vernata (Peck.)]. When both LD50 values and rates of parasitism of the hosts were considered together, the most promising nematode for soil applications was S. feltiae against the bertha armyworm.

The effect of insecticides on (Ca 2+ + Mg 2+)-ATPase and the ATP-dependent calcium pump in moth brain synaptosomes and synaptosome membrane vesicles from the bertha armyworm, Mamestra configurata Wlk

The cyclodienes chlordane, heptachlor, aldrin, and toxaphene inhibited both (Ca 2+ + Mg 2+)-ATPase activity and ATP-dependent Ca 2+ transport in brain synaptosome membrane vesicles from the moth, Mamestra configurata, under identical incubation conditions in a similar dose-dependent manner. These cyclodienes appear to affect the outward-directed ATP-dependent calcium pump in moth brain synaptic sites in a specific manner. 1,1,1-Trichloro-2,2-bis-( p-chlorophenyl)ethane (DDT) inhibited (Ca 2+ + Mg 2+)-ATPase activity but had no corresponding inhibitory effect on ATP-dependent calcium transport and, at high concentrations (>10 −5 M), strongly stimulated calcium transport. DDT appears to affect calcium movement in brain synaptosomal preparations of M. configurata in a way that may not involve the ATP-dependent calcium pump. The pyrethroids permethrin and decamethrin were weak inhibitors of moth brain (Ca 2+ + Mg 2+)-ATPase. Allethrin was an effective inhibitor of enzyme activity and a potent inhibitor of calcium transport. Inhibition of the ATP-dependent calcium pump may contribute to the action of some pyrethroids in insects. Organophosphates, carbamates, and formamidines were weak inhibitors of the moth brain (Ca 2+ + Mg 2+)-ATPase. Changes in the activity of synaptosomal (Ca 2+ + Mg 2+)-ATPase in the brains of moths after in vivo poisoning with chlordane, DDT, and allethrin were consistent with the effects of these insecticides in vitro.

High affinity (Ca 2+ + Mg 2+)-ATPase in adult brain synaptosomes of the bertha armyworm, Mamestra configurata Wlk.

Ca 2+ + Mg 2+)-ATPase in synaptosomes prepared from the adult brain of Mamestra configurata was strictly dependent on ATP and had a single, high-affinity binding site for ATP ( K m = 122 μM). The enzyme was stimulated by Mg 2+ ( K m = 85 μM) and was maximally active in the presence of 40 mM K +. The enzyme was insensitive to ouabain, an inhibitor of (Na + + K +)-ATPase. Moth brain synaptosomal (Ca 2+ + Mg 2+)-ATPase was stimulated by low concentrations of Ca free 2+ and appeared to have two kinetically distinct binding sites for calcium ion, one with a very high affinity for Ca free 2+ at nanomolar concentrations and the other with a lower affinity for Ca free 2+ at micromolar concentrations. The lower-affinity binding site of the moth brain synaptosomal (Ca 2+ + Mg 2+)-ATPase appears to correspond to the Ca 2+ binding site of (Ca 2+ + Mg 2+)-ATPase in mammalian brain synaptosomes. The high-affinity binding site of the moth brain enzyme for Ca free 2+ ( K m = 0.11 nM) has not been described previously in the literature and conceivably may represent a unique class of high-affinity binding sites for calcium in insect brain. Moth brain (Ca 2+ + Mg 2+)-ATPase displays the same high affinity for Ca free 2+ ( K m = 0.11 nm) as described earlier for ATP-dependent Ca 2+ transport ( K m = 0.1–0.2 nM) in synaptosome membrane vesicles, indicating that the two processes are functionally coupled in the synaptic membrane and contribute to the maintenance of calcium homeostasis in the brain of M. configurata.

MONITORING POPULATION LEVELS OF EIGHT SPECIES OF NOCTUIDS WITH SEX-ATTRACTANT TRAPS IN SOUTHERN ALBERTA, 1978–1983: CONSISTENCY OF TRAP CATCHES AND PRECISION OF POPULATION ESTIMATES

AbstractSex-attractant traps were used to monitor the relative abundances of eight species of cutworm and army worm moths at 81 locations in a 13 000-km2 (5000-mi2) area of southern Alberta from 1978 to 1983. Clover cutworm (Discestra trifolii (Hufn.)), variegated cutworm (Peridroma saucia (Hbn.)), bertha armyworm (Mamestra configurata Wlk.), and Leucania commoides Gn. were monitored during spring and early summer, and redbacked cutworm (Euxoa ochrogaster (Gn.)), darksided cutworm (Euxoa messoria (Harr.)), pale western cutworm (Agrotis orthogonia Morr.), and army cutworm (Euxoa auxiliaris (Grt.)) during late summer and fall.The ranking of moth catches among locations within years was highly consistent, indicating that the spatial pattern of abundance within the survey area remained stable during each flight period. The corollary is that differences in population levels among locations were being consistently detected. Most of the species also exhibited a considerable degree of consistency of pattern of abundance between consecutive years and to some extent over all years.Estimates of the variability associated with individual traps, between duplicate traps, and among locations were obtained for each species. The within-location variability was always much less than the among-location variability, indicating that a meaningful measure of the relative population level at each location was being obtained. When abundance levels approached economic thresholds the likelihood of moth catches in duplicate traps being within 20% of the mean catch for a location was usually greater than 80%. Year-to-year differences in mean trap catches were frequently significant at the 95% confidence level and the monitoring system could detect relatively small changes in population level between years. Season cumulative trap catches are a composite measure of abundance and the mate-searching activity of males. Weather conditions that restrict male activity are also likely to reduce oviposition by females. Cumulative trap catches may therefore be closely correlated with realized fecundity.

PREDICTING LARVAL ABUNDANCE OF THE BERTHA ARMYWORM, MAMESTRA CONFIGURATA WLK., IN MANITOBA FROM CATCHES OF MALE MOTHS IN SEX ATTRACTANT TRAPS

AbstractTwo cone-orifice-type traps baited with (Z)-11-hexadecen-1-ol acetate (1.0 mg) and (Z)-9-tetradecen-1-ol acetate (0.05 mg) were placed in each of 5–13 canola (Brassica spp.) fields per year for 7 years at locations distributed throughout the area in Manitoba subject to outbreaks of the bertha armyworm, Mamestra configurata Wlk. (Lepidoptera: Noctuidae). The number of male moths per trap varied from 0 to 821 in the 90 fields trapped. Larval density, in the trap fields and in 185 nearby canola fields, varied from 0 to 105 per square metre. There was a direct relationship between the number of moths per trap and the density of late-instar larvae (L4–L6) for the trap fields and for nearby (within 5 km) fields but variability was loo high to allow accurate prediction of larval densities for individual fields. However, the number of moths per trap could be used to predict the proportion of fields in the vicinity of the trap field that would have larval densities above the economic threshold. No fields with above-threshold larval densities occurred with captures of <20 moths per trap. The proportion of fields with larval densities above the economic threshold increased from 0.10 with 20–30 moths per trap, lo 0.19 with 30–60 moths per trap, 0.64 with 70–100 moths per trap, and 0.91 with over 100 moths per trap. Contamination of catches by non-target species of noctuid moths had insignificant effects on the accuracy of these predictions because even if they were misidentified as M. configurata the number of moths per trap changed only marginally. Populations of M. configurara were higher and local outbreaks occurred more frequently in canola-growing areas adjacent to morainic hills along the Manitoba Escarpment, whereas populations were low in areas of the Manitoba Lowlands and of the Western Uplands. A proposed monitoring system for M. configurata in Manitoba is described.

Dual control of pupal diapause by cyclic nucleotides in the bertha armyworm, Mamestra configurata Wlk.

Treatment of diapausing pupae of M. configurata with dibutyryl cyclic AMP or 8-(4-chlorophenylthio) cyclic AMP (CPT cyclic AMP) reduced the incidence of eclosion to zero compared to about 15% for controls, whereas treatment with cyclic GMP increased eclosion to more than 90%. Treatment with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) resulted in a high incidence (79.8%) of eclosion, but treatment with dibutyryl cyclic AMP + IMBX or CPT cyclic AMP + IBMX gave low incidences (<9.1%) of eclosion. Other methylxanthines (theophylline, 8-phenyltheophylline, caffeine) and papaverine had relatively little effect on eclosion even at high doses. Treatment of post-diapause pupae with dibutyryl cyclic AMP or CPT cyclic AMP resulted in a low incidence (<5.0%) of eclosion compared to 98.8% eclosion in controls. Suppression of eclosion was more effective if dibutyryl cyclic AMP was given within the first 2 days of pupal-adult development at 20°C and became less effective as development progressed, indicating that dibutyryl cyclic AMP inhibits endocrine events initiating development rather than inhibiting subsequent metamorphic development. Treatment of post-diapausing pupae with cyclic GMP, IBMX, other methylxanthines or papaverine did not affect eclosion. These results are consistent with a dual control of pupal diapause in M. configurata by cyclic nucleotides, with cyclic AMP acting to maintain diapause and cyclic GMP acting to terminate it.

Ecdysteroid levels during post-diapause development and 20-hydroxyecdysone-induced development in male pupae of Mamestra configurata Wlk.

Post-diapause development in male pupae of Mamestra configurata Wlk. was characterized by the appearance of large, transitory peaks of ecdysone (2.8 μg/g live wt) at day 8 and 20-hydroxyecdysone (2.2 μg/g) at day 12 which declined to low levels prior to adult eclosion at day 28. Treatment of diapausing pupae with 20-hydroxyecdysone elicited a progression of dose-dependent physiological and pathological effects, including termination of diapause, development, accelerated development, and accelerated development leading to malformation and death. At a dose of 7.5 μg 20-hydroxyecdysone/g, all treated pupae terminated diapause, developed with little mortality and produced a high proportion of morphologically perfect adults. However, there were no large peaks of ecdysone or 20-hydroxyecdysone in treated pupae, possibly due to feedback inhibition by 20-hydroxyecdysone. At doses greater than 7.5 μg/g, development was accelerated markedly, survival decreased precipitously (0% at 15 μg/g) and the proportion of malformed adults increased sharply. Pupae that received a lethal dose of 20-hydroxyecdysone died almost synchronously after undergoing accelerated development for 18–20 days, indicating that they encounter a common, hormone-induced developmental block. Pupae receiving 15 μg/g also showed no edcysone or 20-hydroxyecdysone peaks, but had a prolonged period of hyperecdysonism which likely caused their accelerated development and death.

SURVIVAL OF PUPAE OF MAMESTRA CONFIGURATA (LEPIDOPTERA: NOCTUIDAE) AND TWO OF ITS PARASITES IN UNTILLED AND TILLED SOIL

AbstractThe survival of Mamestra configurata Wlk. was determined from autumn and spring samples in 1973/74, 1980/81, and 1981/82 taken from unfilled and tilled portions of 12 fields of canola (Brassica campestris L. and B. napus L.). Survival from the pre-pupal stage in the autumn to post-diapause pupae in the spring varied from 2.9 to 56.5% in unfilled soil and from 0 to 25.4% in tilled soil. In untilled soil, the variations among fields in total mortality of M. configurata were related to parasitism by Banchus flavescens and to overwintering mortality. In tilled soil, overwintering mortality accounted for most of the variability in total mortality among fields. The percentage of mortality from injury to pupae, and their disappearance following tillage, greatly increased but this type of mortality did not account for much of the variability in total mortality. The disappearance of pupae following tillage was attributed to predation. In both untilled and tilled soils, the amount of overwintering mortality was related to the depth of accumulated snow, and mortality was lower in untilled soil because the stubble trapped more snow. The survival of M. configurata was not related to soil type, the type of tillage equipment, or the frequency of tillage. The number of adults emerging from untilled and tilled soil in one field were 2.58 and 0.27/m2 for M. configurata, 5.22 and 2.85/m2 for the parasite B. flavescens, and 4.46 and 3.60/m2 for the parasite Athrycia cinerea, indicating that the survival of the parasites was less affected by tillage than that of their host.Tillage may reduce the frequency and severity of outbreaks of M. configurata not only by increasing mortality but also by differentially affecting the survival of its main parasites.

Effects of cold stress during pupal diapause on the survival and development of Mamestra configurata (Lepidoptera: Noctuidae).

The effects of exposing diapausing pupae of Mamestra configurata Wlk. to temperatures from -5° C to-20° C during a 140-day experimental period were reduced survival to post-diapause stages, reduced survival to emergence as malformed or normal adults, and a reduced rate of post-diapause development. Pupae given a continuous exposure of variable length to -10° C and pupae given the same exposure to -10° C, interrupted by 28 days at 0° or -5° C, had the same survival, indicating that repair of cold injury does not occur at 0° or-5° C. Assuming that the effects of low temperatures were additive, not only for exposures to one temperature but also for exposures to different combinations of temperatures, survival was decribed by a polynomial: [Formula: see text] where p=the proportion in post-diapause stages and t=the number of days of exposure to the temperature given by the subscript. The values of the coefficients (C) were inversely related to the temperature of exposure (T): log10 C=-2.87-0.159 T. In validation experiments, the model accurately predicted survival of pupae in the laboratory and in soil under natural snow-cover or in soil where snow cover was maintained at <2 cm through a complete winter. Our results suggest that: (1) symptoms of cold injury, from death in the stage exposed through death, malformation or retarded development in post-exposure stages represent a continuum that can be produced by varying the exposure time at temperatures that cause cold injury; (2) repair does not occur at these temperatures nor at slightly warmer temperatures (e.g. at 0° C for M. configurata pupae); (3) the total amount of injury is not affected by the sequence of temperatures to which the insect is exposed; (4) freezing is not responsible for the observed cold injury.

Regulation by Ca 2+ and calmodulin of brain adenylate cyclase from the moth, Mamestra configurata Wlk

The effects of calcium ion and calmodulin on adenylate cyclase from the brain of the moth, Mamestra configurata, were determined in a particulate brain fraction that had been depleted of these factors by repeated washing with buffers containing the divalent metal chelator EDTA and the calcium chelator EGTA. Levels of free Ca 2+ in the enzyme reaction mixtures were controlled by an EGTA-Ca 2+ buffer system and estimated using a computer programme. Adenylate cylase in the washed brain fraction exhibited a biphasic response to Ca 2+ in the presence of added calmodulin. The first response was a 1.5-fold stimulation of enzymic activity which occurred in the presence of 0.08 μM of free Ca 2+ and 0.10 μM calmodulin (half-maximal stimulation at [ Ca 2+] = 0.03 μM). No stimulation was observed in the absence of added calmodulin, consistent with the view that a Ca 2+-calmodulin complex is required to activate the enzyme. The second response was a pronounced inhibition of adenylate cyclase (half-maximal inhibition at [ Ca 2+] = 3.5 μM) which occurred almost equally in the presence or absence of added calmodulin. The activity of octopamine-stimulated adenylate cyclase in the washed brain fraction was also modulated by Ca 2+ and calmodulin. The maximal reaction velocity in the presence of 0.08 μM free Ca 2+ was increased 1.4-fold by calmodulin but the K a for octopamine (1.6 μM) remained unchanged.

The effect of single and combined doses of chlordimeform and permethrin on cAMP and cGMP levels in the moth, Mamestra configurata Wlk

Treatment of adult males of the moth, Mamestra configurata, with chlordimeform caused large increases (up to 27-fold) in the concentration of cAMP in the head, thorax, and abdomen but had little effect on cGMP. This pesticidal effect, termed A +G 0, likely results from the interaction of chlordimeform (or a metabolite) with an octopamine-sensitive adenylate cyclase present in the brain and other tissues. Treatment of moths with permethrin caused substantial increases (up to 3.4-fold) in the concentration of cGMP in the head and thorax but had little effect on cAMP. This effect, termed A 0G +, may result from a disturbance of cholinergic function. Treatment of moths with a combined dose of chlordimeform and permethrin caused increases in the concentration of both cAMP and cGMP (A +G + effect) in the head and thorax and had a synergistic effect on mortality. The synergistic effect on mortality appears to be caused by the disruption of distinct and different physiological systems by the A +G 0 and A 0G + pesticides. The hypothesis that A +G 0 and A 0G + pesticides, when combined, will exhibit synergism is supported by examples from the literature.

Developmental changes in brain taurine levels during metamorphosis of the moth, Mamestra configurata Wlk.

Taurine in the brain of Mamestra configurata rose rapidly during the first half of metamorphosis until its amount and concentration were thirty fold and twenty fold higher than found in the pupa. Taurine levels then fell rapidly to the low amount and concentration found in the brain of the adult moth. The predominant source of increased brain taurine levels during the initiation of adult development was the blood as determined by quantitative radioisotope uptake experiments. Taurine was not taken up from the blood by the brains of pupae that had not completed ‘diapause development’, indicating a rigid compartmentalisation of taurine between the blood and brain during the prolonged period of ‘diapause development’. The change in the permeability of the brain to taurine from a state of apparent exclusion to one of rapid uptake may be an important event in the initiation of adult development. The highest levels of brain taurine were found during the period of intensive brain development, and especially during the development of the massive optic lobes which contained high concentrations of taurine. It is hypothesised that taurine, in addition to its neurochemical function in the ‘mature’ brains of the pupa and adult may have a special role in brain developmental processes per se.

The biosynthesis, function and fate of taurine during the metamorphosis of the noctuid moth Mamestra configurata Wlk.

Taurine is only a minor constituent of growing larvae and prepupae of Mamestra configurata. Following pupation there is a massive synthesis and accumulation of taurine in the pupa. Radioisotope experiments with [ 35S]-cysteine demonstrated that labelled cysteamine, hypotaurine and taurine were formed rapidly following the injection of labelled cysteine into two-day-old pupae. No radioactivity was found in either cysteine sulphinic acid or cysteic acid. The biosynthesis of taurine from cysteine in the pupa appears to be via: cysteine → cysteamine → hypotaurine → taurine. Newly-synthesized taurine was liberated into pupal blood and initially accumulated there. Most of the taurine in the blood of the non-diapausing pupae was taken up by developing adult structures, and especially by the flight muscles. More than 90% of the taurine synthesized during metamorphosis was found in the thorax of the adult moth, indicating an important role for taurine in the flight muscles. Diapause-programmed individuals also synthesized and accumulated large amounts of taurine following pupation. Taurine was stored in the blood of the diapausing pupa for later use when development resumed. Diapause-related functions for taurine may include membrane stabilization and diapause maintenance.

Changes in brain octopamine levels during metamorphosis of the moth, Mamestra configurata Wlk

During metamorphosis, the amount of octopamine in the brain of Mamestra configurata increased by almost 30-fold, from 0.45 pmoles per brain in the pupa to 12.6 pmoles per brain in the adult. When increases in brain weight were taken into account, the change was more than ten-fold, from 9.8 pmoles per mg dry brain weight to 110 pmoles per mg dry brain weight. The rise in the level of octopamine occurred rapidly during the last ten days of metamorphosis and paralleled increases in the activity of octopamine-sensitive adenylate cyclase both in time and in relative magnitude of change. The highest concentration of octopamine and the highest specific activity of octopamine-sensitive adenylate cyclase occur in the optic lobes of the adult brain. These observations support a neurotransmitter or neuromodulator role for octopamine in the optic lobes. The low concentration of octopamine and weak activity of octopamine-sensitive adenylase cyclase in the pupal brain of M. configurata appear to be correlated with the low level of sensory input and limited behavioural range of the dormant pupa overwintering in the soil in darkness at sub-zero temperatures. The development of an enhanced octopaminergic system during brain ontogeny may be required to process and/or modulate the greatly increased sensory input of the volant adult, and in particular, to modulate input from the compound eyes.

Characterization of an octopamine-sensitive adenylate cyclase from insect brain (Mamestra configurata Wlk.).

An adenylate cyclase present in the brain of the moth Mamestra configurata Wlk. that is stimulated selectively by low (micromolar) concentrations of octopamine has been characterized with respect to several properties. The optimum pH, optimum ATP:Mg2+ ratio, the concentration of ATP required for half-maximal and maximal reaction velocity, metal ion specificity, effect of NaF, and effects of GTP and 5'-guanylylimidodiphosphate were in general similar to those of catecholamine-sensitive adenylate cyclases from various regions of mammalian brain. However, ethylene glycol bis-(beta-aminoethyl ether)-N,N-tetraacetic acid (EGTA), a calcium chelator, stimulated both basal and octopamine-sensitive enzyme activity in the insect brain, whereas in mammalian brain EGTA is usually observed to inhibit basal activity but not catecholamine-stimulated activity. Adenylate cyclase activity of the 47,000 g particulate fraction of the insect brain was almost undetectable in the absence of added GTP. Addition of saturating concentrations (100 micrometer) of GTP to the particles restored about 30% of the basal and octopamine-sensitive enzyme activity present in the homogenate. Addition of 100,000 g supernatant to the particles doubled both basal and octopamine-sensitive enzyme activity in the presence of saturating concentrations of GTP, indicating that in addition to GTP, a cytosolic factor(s) is necessary for enhanced adenylate cyclase activity.

Identification of specific dopamine- and octopamine-sensitive adenylate cyclases in the brain of Mamestra configurata Wlk.

The brain of the moth Mamestra configurata Wlk. contains two discrete types of adenylate cyclase activity: one is stimulated specifically by low concentrations of dopamine ( K a = 0.75 μM) and the other is stimulated specifically by low concentrations of octopamine ( K a = 1.5 μM). The dopamine- and octopamine-sensitive adenylate cylases were found in homogenates and washed centrifuged particles from brains of diapausing pupae, diapause-terminated pupae and developing pharate adults. Phentolamine, an alpha-adrenergic antagonist, strongly inhibited activation of the brain adenylate cyclases by dopamine and octopamine, whereas propanolol, a beta-adrenergic antagonist was relatively ineffective. Although the brain lacks adenylate cyclases stimulated specifically by tyramine, phenylethylamine, phenylethanolamine, and noradrenaline, high concentrations of these amines can stimulate adenylate cyclase activity, probably through partial activation of receptor sites for dopamine and octopamine. No evidence for a serotonin-sensitive adenylate cyclase was found in the brain of M. configurata. The putative transmitters glycine, glutamic acid, γ-amino butyric acid, taurine and histamine had no effect on adenylate cyclase activity in brain homogenates. Carbachol, a muscarinic and nicotinic cholinergic agonist, was also without effect. The physiological role of the dopamine-and octopamine-sensitive adenylate cyclases in neurotransmission in the brain of M. configurata is discussed.

Levels of brain cyclic AMP and cyclic GMP during the initiation of adult development in the bertha armyworm, Mamestra configurata Wlk

Levels of brain cyclic AMP and cyclic GMP in Mamestra configurata remained essentially unchanged during the first three days of pharate adult development after pupae were transferred from eight months of cold storage at 5° to 20°C. Thereafter, cyclic AMP levels increased six-fold over a two week period from 0.22 pmole/brain to about 1.3 pmole/brain. Cyclic GMP levels doubled over the two week period, from 0.09 pmole/brain to about 0.19 pmole/brain. These changes appeared to follow the activation of brain neurosecretion rather than precede it. Brain cyclic AMP and cyclic GMP levels of non-developing pupae remained virtually unchanged at about 0.27 and 0.048 pmole/brain, respectively, following their transfer from two months of cold storage at 5° to 20°C. Cyclic AMP: cyclic GMP ratiosthus increase from about 2:1 in the pupal brain to 6:1 oreven 7:1 in the differentiating brain of the pharate adult. The results are consistent with an important role for cyclic AMP and cyclic GMP in brain processes that become established during differentiation of the adult brain, and perhaps in the case of cyclic AMP, in the differentiation process itself.

Correlation between organophosphate poisoning, acetylcholinesterase inhibition, and increased cyclic GMP levels in malathion-treated insects

Organophosphate poisoning with malathion caused large increases (up to 125 and 440%, respectively) in the level of cyclic GMP in larvae of Mamestra configurata Wlk. and in the fly Sarcophaga bullata Parker. Cyclic AMP was little affected. The malathion-induced increase in cyclic GMP was time and dose dependent. Time-course studies with the head and thorax of S. bullata demonstrated that the increase in cyclic GMP level occurred precipitously after a lag period of about 1 h, during which time the activity of acetylcholinesterase (EC 3.1.1.7) was progressively inhibited. The abrupt increase in cyclic GMP began when acetylcholinesterase activity had been inhibited to a sufficient extent to permit accumulation of acetylcholine. It is suggested that the accumulation of acetylcholine in the malathion-poisoned insects caused cyclic GMP levels to rise. Cyclic GMP may have a role in cholinergic transmission in normally functioning insect neural tissue. Increased levels of cyclic GMP induced by organophosphate and organocholorine (Bodnaryk, R. P. (1976) Can. J. Biochem. 54, 957-962) insecticides appear to be a vital and previously unrecognized biochemical lesion in insects poisoned by these compounds.