Moth Emergence Research Articles

Control of the Codling Moth with Experimental Insecticides, 1994

Abstract The trial was conducted in a 30 yr old Bartlett pear block with chemicals applied to 4 single tree replicates arranged in a RCB. Materials were applied with conventional, high pressure hand gun equipment and sprayed to runoff or about 400 gpa. Each chemical was applied three times in a season-long, phenologically timed CM program. Two different timings were employed, based on CM biofix as determined by the first male moth captured in pheromone baited traps. A standard larvicidal timing was used in treatments receiving Guthion, A 303,603 and one treatment of RH 5992. This standard program consisted of a first application at about 250 degree days (dd) following biofix; the second 28 days later and the final at about 1250 dd, or 250 dd after the predicted emergence of second generation moths. Corresponding dates to the above schedule were 12—13 May, 9 Jun and 13 Jul. An ovicidal timing was employed for the insect growth regulator (IGR) fenoxycarb. The timings for fenoxycarb was a first application at 50-100 dd after biofix (27 Apr), the second 28 days after the first, and the third at 1050 dd (7 Jul). Evaluation of CM damage was made by recording the number of larval entries per 50 fruit per replicate at the end of the first CM generations (7-9 Jul) and again at harvest (17 Aug). Densities of PP immatures, spider mites (TSM, ERM) and PRM were estimated at three post-treatment intervals (20 Jun, 25 Jul, 16 Aug) by recording their numbers from brushing of 20 leaves (10 old, 10 new) per replicate. Adult PP and predators (lacewings, earwigs, and predaceous bugs) were estimated from two beating tray samples per replicate taken on 22 Jun, 27 Jul, and 19 Aug.

Inhibitory effects of actinomycin D and cycloheximide on neuronal death in adult Manduca sexta

A decline in circulating 20-hydroxyecdysone permits the emergence of the adult Manduca sexta moth; this endocrine signal also triggers the death of approximately half of the neurons in the unfused abdominal ganglia of the moth central nervous system. This programmed death of neurons was markedly reduced by treatment with either actinomycin D (an RNA synthesis inhibitor) or cycloheximide (a protein synthesis inhibitor). Similar results were found after addition of these agents to ventral nerve cord cultures. The effectiveness of these treatments in delaying or blocking neuronal death depended upon their time of administration relative to the normal time of post-emergence death in the particular motoneuron under study: late-dying neurons, for example, could still be saved by these treatments even after early-dying neurons had already initiated degeneration. In both intact moths and cultured ventral nerve cords, the ability of actinomycin D to prevent neuronal death waned at the same time at which replacement of the steroid hormone could no longer block neuronal death. This suggests that the steroid commitment point represents the time at which the genes that mediate cell death are transcribed. Cycloheximide remained effective in delaying or blocking neuronal death until shortly before the onset of degeneration, suggesting that ongoing protein synthesis is essential for the initiation of the degeneration response.

Apple, Airblast Evaluation of Insecticides, 1993

Abstract Experimental sprays were applied to 3 tree plots in a randomized block design consisting of 2 replicates of ‘Yorking’ and 2 replicates of ‘Golden Delicious’ with a buffer tree between plots and a buffer row between blocks. These trees were spaced 20 × 30 ft apart and were 19 years old. Experimental sprays were applied with a Friend Airmaster ‘309’ calibrated to deliver 100 gpa at 2.0 mph. Application dates and materials varied between treatments and are listed in the table for WALH. All applications were complete sprays. A routine schedule of fungicides (Dithane 75DF, Nova 40WP, captan 50WP and Benlate 50DF) was maintained throughout the experiment. Effectiveness on SA was evaluated by counting aphid-infested leaves/10 top terminals, and aphids/most infested leaf. The effect of the sprays on WALH was evaluated by counting nymphs/25 injured leaves/tree. Effectiveness of test chemicals on ERM and ZM was evaluated by counting these mites several times during the season on samples of 25 random leaves/tree, 100 leaves/treatment. The effect of sprays on S. punctum was evaluated by 3-min counts of adults and larvae around the periphery of the test trees. STLM were evaluated by a 5-min count of mines around the periphery of the trees at the end of each of the first two generations before peak emergence of adults. OFM shoot injury was assessed by making a 3 min observation around the periphery of each tree and counting injured shoots. Internal feeding lepidoptera were evaluated with a 5-min count of apples exuding frass and the total number of apples evaluated to give percent injured apples. Effectiveness of chemicals on fruit feeders was assessed for injury by scoring drop apples on 6 and 21 Jul and 3 and 16 Aug and picked samples of 50, 100 and 100 fruit per replication on 16 Aug, 3 and 20 Sep, respectively. Pest pressure was extremely high throughout the season. Fruits were rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>51% russeted surface). Possible ranges are 0-30 (none to raised lenticels) 31-60 (raised lenticels to 1- 10% russeted surface), 61-90 (1-10% to 11-25% russeted surface, 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to >51% russeted surface). Effects on parasitoids attacking CM and OFM were evaluated several times during the season on a single tree within each plot by picking up to 20 apples exuding frass in a 10-min count and rearing the larvae in the laboratory on a semi-synthetic lima bean diet at 20 °C, 16:8 D:L. Injured apples were collected on 7 and 22 Jun, 7 and 19 Jul, 4 and 18 Aug, and 2 Sept. Larvae of CM and OFM were transferred singly to diet cups on each collection date and monitored several times a week for adult moth and parasitoid emergence for 5 weeks. Two species of braconid parasitoids were found during these evaluations, Macrocentrus delicatus which was by far the most common and Charmon extensor. Rates of parasitism for each treatment were calculated by dividing the total number of parasitoids by the total number of parasitoids plus total number of CM and OFM adults.

Mortality of Helicoverpa zea (Lepidoptera: Noctuidae) Pupae in Ear-Stage Field Com

The factors having an impact on the survival of the F2 seasonal generation of Helicoverpa zea (Boddie) pupae in southwestern Arkansas field corn were identified and quantified. Last instar (fifth or sixth instar) field-collected com earworm larvae (480 per yr) were allowed to pupate in fields under four treatments designed to provide three levels of natural enemy exclusion. Mortality of these pupae and samples of feral pupae were determined and mortality factors were identified. Recovery of exuviae and remains from placed pupae were excellent (94 and 96% in 1990 and 1991, respectively). Moths emerged from the vast majority of test pupae (82.3 and 93.9% in 1990 and 1991, respectively). The exclusion treatments had no effect on the incidence of mortality in either year. Mortality was higher in 1990 (11.7%) than in 1991 (1.9%) because of the collapse of emergence tunnels prior to or during moth emergence. The increased incidence of collapse may have been caused by a significantly lower clay content (7.03%) in 1990 than in 1991 (16.4%). Observed biotic mortality was extremely low (2.1% and <1% in 1990 and 1991, respectively) in spite of a rich predator fauna as identified from pitfall traps. The large number of earworm larvae surviving to pupation following larval development in the ear of field corn, combined with the observed low mortality rates, suggests that a large number of moths would emerge from each hectare of corn at a time when other crops, particularly cotton, are attractive for oviposition. Enhancement of pupal mortality in ear-stage corn by cultural or chemical means is impractical or impossible, thus providing support for implementation of a biological control program that targets H. zea pupae.

Oviposition by the Forest Tent Caterpillar (Lepidoptera: Lasiocampidae) and Acceptability of Its Eggs to Trichogramma minutum (Hymenoptera: Trichogrammatidae)

Studies were conducted to assess the availability and acceptability of eggs of forest tent caterpillar, Malacosoma disstria Hubner, to Trichogramma minutum Riley for use in inundative releases. Oviposition by the forest tent caterpillar occurred 4-19 July and lasted 7-10 d in southern Ontario. At least 50% of the egg-laying activity occurred during the first 3-4 d. Oviposition was initiated on the same day as female moth emergence, 2 d after male moth emergence. Pheromone traps baited with two-component lures predicted oviposition within 2 d. No Trichogramma emerged successfully from 0- to 7-d-old host eggs, although the survival of tent caterpillar embryos exposed at this age to the parasitoids was reduced significantly (from 97.5 to 42.3%). The greatest number of Trichogramma emerging from caterpillar egg masses (72.7%) was observed in those eggs exposed to parasitoids 21 d after oviposition, with 43.5 and 12.5% emergence from egg masses exposed at 14 and 28 d after oviposition, respectively. A tent caterpillar egg mass contained 109.8 +/- 14.8 (mean +/- SE) eggs; parasitoids emerged from 14.4 +/- 3.5 of these eggs (13.1% egg parasitism). The number of parasitoids emerging from each parasitized egg ranged from 5.0 to 11.0; 69.5% were female and development at 20 degrees C took 14.2 +/- 0.2 d. Removal of the spumaline layer from the egg masses increased emergence of parasitoids very slightly. No Trichogramma successfully overwintered in forest tent caterpillar eggs, although a single dead parasitoid (0.2%) was observed infrequently in eggs simultaneously with a dead pharate larva. Trichogramma possibly can be used in inundative releases against M. disstria; however, further studies are needed to determine why the parasitoid kills but does not emerge from tent caterpillar eggs < 14 d old.

Seasonal bionomics of Heliothis armigera (Hubner) (Lepidoptera: Noctuidae) in the Terai Belt of northeastern Uttar Pradesh

Heliothis armigera (Hubner) completed five generations in the laboratory, as well as in the field, in a year. The first generation was completed from the first week of December to the fourth week of February, the second generation from the second week of February to first week of April. The third generation from third week of August passing through the extreme summer, the fourth generation during monsoon period and the fifth last generation from the third week of September to the fourth week of November. The seasonal variation in generation time is largely due to extreme variations in ecological factors, temperature (10–45°C), photoperiod (10–14 hr), relative humidity (15–95%) and rainfall. These factors also affect the percentage of pupation, emergence and fecundity of the female moths. Males outnumbered the females in the first, second and fifth generation. The females lived longer than males in all generations.

Emergence of Male-Sterile Heliothis virescens (Lepidoptera: Noctuidae) Backcross Moths at a Central Release Point and Their Resulting Spatial Distribution

Heliothis virescens backcross moths are most effectively released in wide-area release programs from pupae placed in the field prior to moth emergence. A significantly greater moth emergence was obtained in the field from unharvested pupae in rearing trays than was obtained from harvested pupae. Mating, oviposition, and egg viability of emerged female moths were not adversely affected by handling procedures. Moths released from emergence containers were recovered in the most distant trap, 5.5 km, from the release point. However, the greatest number of released moths was captured in pheromone traps within 1.7 km of the release point.

Developmental neuroethology of insect metamorphosis.

During metamorphosis, the insect nervous system must change to accomodate alterations in body form and behavior. Studies primarily on moths have shown that these changes involve the death of some larval neurons, the conservation and remodeling of others, and the maturation of new, adult-specific cells. The motor and sensory sides of the adult CNS vary in this regard with the former being constructed primarily from remodeled larval components, whereas the latter arises primarily from new neurons. Neuronal remodeling has received considerable attention. Larval-specific dendritic fields are pruned back during the larval-pupal transition, followed by the sprouting of adult-specific dendrites. Simple reflexes have been used to correlate these neuronal changes with the acquisition or loss of particular behaviors. The loss of the proleg retraction reflex is associated with the regression of the dendritic arbors of the proleg motoneurons. By contrast, expansion of axon arbors of the gin-trap afferents is necessary, but not sufficient, for the assembly of the gin-trap reflex in the pupal stage. The stretch receptor reflex provides a third example in which a new dendritic field in the adult form of a neuron is associated with new adult-specific connections. Interestingly, these connections are masked by persisting larval contacts until the emergence of the adult moth. For the metamorphosis of more complex behavioral circuits, some, such as that for flight behavior, seem to be assembled de novo, whereas others, like that for adult ecdysis behavior, show conservation of some circuit elements from the larval stage but with the superposition of some adult-specific components.

Resistance in certain maize cultivars to first and third-instar Chilo partellus larvae

The resistance/susceptibility levels of ten maize (Zea mays L.) cultivars to neonates and 3rd-instar larvae of Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) were measured in the field and screenhouse experiments. The maize cultivars tested were: Inbred A, Mp 704, V-37, Population 10, Hybrid 511, Katumani Composite B, ER-29 SVR, Poza Rica 7832, ICZ2-CM, and MMV 400. Most cultivars were found susceptible to 3rd-instar larvae based on the incidence of dead heart symptoms, foliar feeding and stem tunnelling caused by stem borers in both the field and screenhouse experiments. However, the maize cultivars V-37, MMV 400 and Poza Rica 7832 sustained significantly lesser damage than the other cultivars when infested with neonates or 3rd instar larvae. The screenhouse experiments conducted with five maize cultivars, i.e. Inbred A, Mp 704, V-37, ER-29 SVR, and Poza Rica 7832 showed that neonates fed less on the resistant than the susceptible maize cultivars but feeding by the 3rd instars was equally high on all the maize cultivars except Mp 704 on which the larvae fed less than the others. In the cultivars infested with neonates, the mean period for 50% moth emergence P50 was longest on Mp 704 followed by Poza Rica 7832, ER-29 SVR, V-37 and Inbred A. In the cultivars infested with 3rd-instars, P50 was longest for Poza Rica 7832 followed equally by the remaining cultivars. On the basis of the evidence presented we here conclude that neonates of C. partellus are sensitive to the growth inhibiting effects of the resistant maize cultivars Mp 704, V-37, and Poza Rica 7832 but the older larvae are insensitive to these effects of Mp 704 and V-37 but not of Poza Rica 7832.

Nocturnal observations on the emergence and flight behaviour of Helicoverpa armigera (Lepidoptera: Noctuidae) in the post-rainy season in central India

AbstractA range of techniques was used to quantify the nocturnal flight behaviour of Helicoverpa armigera (Hübner) in pigeon pea (Cajanus cajan) crops near Hyderabad, in central India. These included visual observations in the field, the use of field cages and a vehicle-mounted net, optical and video imaging in the infra-red, and radar. Moth emergence from the soil was observed to start at dusk and recruitment continued steadily throughout the first half of the night. Little activity was observed in moths on the night of emergence, except for weak flying or crawling to daytime refuges. Flight activity of one-day old moths started about 20 min after sunset, peaked 15 min later and within about an hour of sunset had declined to a low level which persisted for the rest of the night. Flight of reproductively mature moths was most frequent about 1 h after sunset and at this time mainly comprised females searching for oviposition sites and nectar sources. By about 2 h after sunset, flight had decreased markedly, but there was a slight increase in activity in the second half of the night caused by males undertaking mate-finding flights. Under the conditions studied, the majority of H. armigera dispersed below 10 m, and there were no mass ascents to higher altitudes like those observed at outbreak sites of the African armyworm, Spodoptera exempta (Walker) (Lepidoptera: Noctuidae). The contrasting migratory strategies of H. armigera and S. exempta are briefly discussed.

Demonstration of motoneuron-12 sparing in cultured Manduca sexta ventral nerve cords.

The emergence of the adult Manduca sexta moth is accompanied by the death of half of the neurons present in the pupal abdominal nervous system (Truman, 1983). This developmental neuronal death is highly selective, so that the same neurons die at the same time relative to emergence in every moth. In the case of the MN-12 motoneurons, this cell death is regulated both by hemolymph concentrations of a steroid hormone, 20-hydroxyecdysone, and by actions exerted by adjacent ganglia (Truman and Schwartz, 1984; Fahrbach and Truman, 1987). This latter effect, which has been previously described in isolated abdomens and in moths with transected ventral nerve cords, has now been reproduced under controlled culture conditions in which the selectivity and extent of postemergence neuronal death is comparable to that seen in vivo. With respect to the MN-12 neurons found in the most anterior unfused abdominal ganglion, A3, the pterothoracic ganglion appears to be the source of a factor that permits these neurons to die according to their usual developmental schedule.

Searching Behavior of Pediobius furvus (Hymenoptera: Eulophidae) for Eoreuma loftini (Lepidoptera: Pyralidae) in Sugarcane

The behavior of searching female Pediobius furvus Gahan and parasitism of Eoreuma loftini (Dyar) pupae are described from laboratory behavioral and field enclosure studies. P. furvus responded positively to larval tunnel openings and open moth emergence windows in sugarcane stalks as cues to host presence (45.7 and 76.8% of females, respectively). Larvae of the stalkborer E. loftini typically construct frass-filled larval tunnels and closed moth emergence windows, which prevent access by P. furvus under both laboratory and field conditions. When the epidermal covering of the moth emergence window was removed, parasitism by P. furvus was enhanced from 1.4 to 25.5%.

Duration of diapause in the stem borers, Busseola fusca and Chilo partellus

AbstractThe duration of diapause in the stem borers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) was studied in South Africa by collecting diapausing larvae from the field throughout winter (April–August). B. fusca larvae emerged as moth around the middle of October regardless of the date of collection and the length of time they were kept in the laboratory under constant 21 °C. C. partellus larvae collected in April‐June emerged in November, those collected in July emerged in October, and those collected in August emerged in September. Regardless of the collection date C. partellus started to emerge from diapause earlier and moth emergence lasted up to twice as long as in B. fusca. Under laboratory conditions at 60% RH both borer larvae lost about 50% of their body mass during diapause. When provided with water B. fusca larvae lost about 30% of their body mass and adults emerged 20 days earlier than when kept dry. C. partellus, on the other hand, lost only 13% of their body weight and emerged 34 days earlier. The differences between the two species are discussed in light of different types of diapause; i.e., obligatory diapause in B. fusca and facultative diapause in C. partellus.

Evaluation of bivoltine single and double cross hybrids of silkworm, Bombyx mori L. for grainage parameters

Grainage parameters, viz. pupal weight, rate of moth emergence, fecundity and hatching were studied among four bivoltine pure races and their five single and four double cross hybrids of silkworm Bombyx mori L. The significant increase in double cross hybrids over pure races was 11.72, 7.43,19.45 and 12.26% for pupal weight, rate of moth emergence, fecundity and hatching, respectively. The fecundity in double cross hybrids improved significantly over single cross hybrids to the extent of 16.03% whereas pupal weight, rate of moth emergence and hatching increased to the extent of 4.38, 5.90 and 5.76%, respectively. The extent of standard heterosis and heterobeltiosis was maximum in double cross hybrids and the heterosis was more pronounced for fecundity.

CONTROL OF SPRUCE BUDMOTH, ZEIRAPHERA CANADENSIS MUT. AND FREE., IN WHITE SPRUCE PLANTATIONS WITH ENTOMOPATHOGENIC NEMATODES, STEINERNEMA SPP.

AbstractA spruce budmoth population reduction of 82%, as measured by moth emergence, was realized after a foliar spray in which Futura®, a commercial Bacillus thuringiensis Berliner (B.t.) formulation, was added to a suspension of Steinernema carpocapsae (Weiser). The nematode suspension, which took advantage of the wetting and spreading agents in the formulation, was applied to runoff at the rate of 9785 viable infective juvenile nematodes per litre. Mortality was attributed to the nematodes; B.t. was not available to the cryptic larvae. Soil drench treatments were encouraging, and suggested that applications of nematodes to the soil may be feasible.

Modeling the Areawide Impact of Sugarcane Varieties and Predation on Sugarcane Borer (Lepidoptera: Pyralidae) Populations in Southern Louisiana

A simulation model was developed to increase understanding of how varietal resistance and predation may affect sugarcane borer, Diatraea saccharalis (F.), populations on an areawide basis. The model includes the processes of immature development, oviposition, host-dependent mortality, and mortality due to arthropod predation. Varietal parameters in the model were obtained from replicated small-plot evaluation trials. Percentages of bored internodes were used to compare survival of sugarcane borers from the egg stage until establishment in the stalk among sugarcane cultivars with and without predator suppression. A relative survival index was used to estimate survival among cultivars, from establishment in the stalk until pupation. Simulations showed that differences in moth emergence and total emergence would be greatest in the absence of adult exchange among varieties. These studies indicated that the impact of susceptible varieties on sugarcane borer populations might be mitigated if these varieties are dispersed among varieties with greater resistance. Varietal differences observed in small-plot varietal evaluations were substantially magnified during simulations when the amount of adult redistribution among varieties was reduced. Based on this research, data obtained from small-plot varietal resistance studies alone may not adequately address the potential impact that such varieties, when grown on larger acreages, might have on pest populations.

Biology and development of some stored grain pests as affected byδ‐endotoxin andβ‐exotoxin ofBacillus thuringiensis

Exposure of Plodia interpunctella and Sitotroga cerealella to sublethal concentrations of Dipel 2X® (Bacillus thuringiensis var.kurstaki‐HD‐1)with its spores and endotoxin crystals led to an increase in the sum of larval‐pupal duration. A decrease in moth emergence, egg production and fertility was observed with increase of Dipel 2X concentration, while the longevity of the moths was not affected by treatment. Sublethal concentrations of β‐exotoxin (ABG‐6162 A) had no significant effect on the sum of larval—pupal duration of either insect species. Percentage of moth emergence decreased with the increase of β‐exotoxin concentrations. The longevity of both male and female adults of P. interpunctella and of females of S. cerealella were shorter at high concentrations. Egg production in P. interpunctella was reduced by all concentrations of the β‐exotoxin, and hatching of eggs was reduced by concentrations of 15 ppm and above.

USE OF STANDARD TEMPERATURE THRESHOLDS AND PHENOLOGICAL PREDICTION FOR THE EUROPEAN CORN BORER (OSTRINIA NUBILALIS HÜBNER) IN ALBERTA

AbstractA degree-day model was developed for Alberta populations of Ostrinia nubilalis Hübner. Starting with overwintered fifth-instar larvae, the model calculates the temporal distribution of first- and second-instar larvae which are the stages most vulnerable to chemical suppression. Predictions from three alternative models were compared against field data from southern Alberta. Use of a standard 10°C growth threshold to calculate physiological time scales allowed predictions as accurate as those obtained using either a pooled threshold (11.4°C) calculated specifically from Alberta populations, or a model using two thresholds (12.3°C for fifth-instar larvae to adult and 10.2°C for eggs to second-instar larvae) that incorporated significant differences in growth characteristics observed among life stages. We conclude that standard thresholds are sufficient for degree-day models for northern populations of O. nubilalis. The standard model (t0 = 10°C) predicts that moth emergence will peak at ca. 145 degree-days after median pupation, and that numbers of eggs, and first- and second-instar larvae should peak at 200, 310, and 450 degree-days, respectively. Model predictions can be used to time sampling effort in support of management decisions.

The Development of the 1983 Outbreak of the Common Armyworm, Mythimna convecta, in Eastern Australia

A large outbreak of common arymworm began in spring 1983, 6 months after the conclusion of a nation-wide drought, and occurred throughout the major cereal-growing regions of E Australia. Probable source areas were in the extensive grasslands of inland Australia, particularly SW and C Queensland. Population increase appeared to follow a complex sequence of overlapping, complementary generations. Although some generations were initiated directly by the drought-breaking rains, others appeared to arise from isolated thunderstorms which preceded them by several weeks in late summer. Moth emergence occurred in early April, late May, late July, and from late August to November. In each case, except late May, it was hypothesized that there were both local and long-range movements of adults on the synoptic airflows, resulting in moths spreading progressively from several isolated sources into the flourishing grasslands of E Australia. Multitemporal satellite data were used to identify areas of potential armyworm habitat in an inland source area of SW Queensland. Very small patches of suitable habitat were identified during the drought whilst, after the drought broke, 36% of the area comprised green grasses ideal for colonization. The subtropical grasses dried off by late winter and emigration by newly emerged moths on prefrontal airflows enabled the spring populations to colonize the temperate grass regions of inland New South Wales.

EFFECT OF SOIL MOISTURE AND SIMULATED RAINFALL ON PUPAL SURVIVAL AND MOTH EMERGENCE OF HELICOVERPA PUNCTIGERA (WALLENGREN) AND H. ARMIGERA (HÜBNER) (LEPIDOPTERA: NOCTUIDAE)

Prepupae of Helicoverpa punctigera (Wallengren) and H. armigera (Hübner) were allowed to pupate in a black cracking‐clay soil at different moisture levels. No differences in pupal survival and moth emergence were recorded where soil moisture ranged from dry to very wet when prepupae tunnelled into the soil. In a second experiment, simulated rainfall after pupation, but before moth emergence, reduced survival by disrupting emergence tunnels and trapping moths in their tunnels. This effect was greater where prepupae had tunnelled into dry soil than where they had tunnelled into wet soil.