Evaluation of trap designs and food attractants for trapping Eucryptorrhynchus scrobiculatus (Coleoptera: Curculionidae)*

Eucryptorrhynchus scrobiculatus (Motschulsky) is a serious pest of tree of heaven, Ailanthus altissima (Mill.) Swingle in China. Laboratory choice tests were conducted to compare attractiveness of vinegar, ethanol, apple juice, the vinegar-ethanol mixture (VE), vinegar-apple mixture (VA), ethanol-apple mixture (EA) and vinegar-ethanol-apple mixture (VEA) to E. scrobiculatus. VEA showed significantly higher attractiveness to E. scrobiculatus than vinegar, ethanol, apple juice alone, VE, VA or EA. The field experiments were conducted to evaluate the efficiency of commercial pitfall traps baited with different ratios of VEA (Apple: VE, m:m) for trapping E. scrobiculatus. Field evaluations showed that the number of marked and wild E. scrobiculatus in traps baited with the VEA (Apple: VE, 30:70 ratio, m:m) was significantly higher than traps baited with other ratios of VEA. Further testing of four types of trap baited with this VEA (Apple: VE, 30:70 ratio, m:m) indicated that captures in homemade pitfall trap design were significantly higher than in any other trap design (commercial pitfall traps, cross-vane versus traps and six-unit-funnel traps). The results demonstrated that homemade pitfall traps baited with the VEA (Apple: VE, 30:70 ratio, m:m) have potential for E. scrobiculatus monitoring.     

The independent effects of heat,smoke and ash on emergence of seedlings from the soil seed bank of a heathy Eucalyptus woodland in Grampians (Gariwerd) National Park,western Victoria

Abstract The independent effects of smoke, ash, and wet and dry heat treatments on seedling emergence from the soil seed bank were tested for soils from fire-prone heathy woodlands in western Victoria. A total of 763 individuals from 56 species were recorded from the surface soil samples (which covered a total area of 1 m²). Both species richness and density of seedlings was greater for smoke- and heat-treated samples than for controls and ash-treated samples. However, only the density differences were significant. Mean seed bank densities for the smoke and heat treatments ranged from 855 ± 70m^?2 to 1080 ± 58 m^?2 and are similar to estimates obtained elsewhere in Australia for heat-treated soils from dry sclerophyll communities. Of the 56 species recorded, 46 occurred in the smoke and heat treatments but only 33 in the control and ash treatments. The sudden increase in surface soil pH, exchangeable cations and extractable phosphorus which was associated with the ash treatment did not act as a trigger for germination in any of the species recorded here. Chemical constituents from smoke do appear to provide a stimulus separate from the effects of heat, but were not identified with any particular taxa.     

Interaction of larval age and antibiotic on the susceptibility of three insect species to Bacillus thuringiensis

The addition of chlortetracycline hydrochloride to bioassay diets increased the LC₅₀S of the HD-1 isolate of Bacillus thuringiensis 2.4–67.1 times when bioassayed against 4-day-old larvae of Trichoplusia ni, Heliothis virescens, and Ostrinia nubilalis. There were no significant differences in LC₅₀s when bioassays were conducted with neonate larvae in the presence or absence of antibiotic, nor were there any highly significant differences between the LC₅₀s for HD-1 when neonate larvae were used in the presence or absence of antibiotic or when 4-day-old larvae were used in the absence of antibiotic. Viable counts of B. thuringiensis did not increase over time in any of three bioassay diets. There were no differences in activity of pure chlortetracycline hydrochloride and veterinary grade Aureomycin. There was a direct correlation between amount of antibiotic and elevation of HD-1 LC₅₀s when 4-day-old larvae were used. LC₅₀ elevation in presence of antibiotic first appeared in 2-day-old larvae.     

Rearing of a coleopterous predator,Trogossita japonica (Col.: Trogossitidae), on artificial diets

Artificial diets for a coleopterous predator of pine bark and wood borers,Trogossita japonica Reitter (Col.: Trogossitidae) were studied. Diets composed of silkworm pupa-powder, dry yeasts, sucrose, peptone, squid liver oil, agar and distilled water supported larval development. The size of diet-reared adults was smaller than that in the control but they mated and oviposited normally when maintained on prey insects. An aseptic rearing method for the larvae of predator, that required a single diet change, was devised.

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Résumé Nous avons élaboré et évalué quatre milieux semi-synthétiques pour l'élevage deTrogossita japonica Reitter, prédateur d'insectes sous-corticaux et xylophages des pins. Les larves ont été nourries avec des milieux composés de poudre de chrysalide du ver à soie, levure de bière séchée, sucrose, peptone, huile de foie de seiche, agar et eau distillée. Les adultes obtenus ont été plus petits que ceux du lot témoin, mais ils se sont accouplés et ont pondu normalement quand ils ont été nourris avec des proies-insectes. Une méthode d'élevage des larves sur milieu aseptique a été élaborée, laquelle ne nécessite qu'un changement de milieu nutritionnel au cours du développement larvaire du prédateur.

     

Shoot neoformation in clones of Fraxinus pennsylvanica in relation to genotype,site and pruning treatments

Summary Four clones of Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern. were planted in replicated trials at two sites in Manitoba (Morden and Winnipeg) to investigate shoot growth and leaf neoformation in relation to genotype, environment and pruning treatment over a 3 year period. Significant differences were found among clones, years and sites for shoot length and numbers of neoformed leaves. Neoformation was highest shortly after transplanting and then declined. An increase in neoformation was evident following cold related winter injury or loss of terminal buds by late spring frosts. Pruning and terminal bud removal treatments both increased neoformed leaf production relative to control trees. The trees were able to quickly re-establish photosynthetic surface area after injury or treatment and neoformed leaf production was an important component in this recovery strategy. The capacity for neoformation also varied in relation to genotype but appeared to be very plastic, being affected by a wide variety of factors. In addition, the rate or pattern of change in amounts of neoformed leaves over time and locations was variable. Numbers of neoformed leaves increased with shoot length but variation in the relationship suggested that there were differences in internode length as well. Neoformed leaves were highest in the upper part of the crown indicating that there was differential allocation of resources within the crown.     

Effects of taurine supplementation on productive performance,nutrient digestibility and gene expression of nutrient transporters in quails reared under heat stress

This study was conducted to examine the effects of dietary taurine supplementation on productive performance, nutrient digestibility, antioxidant status, and the gene expression of ileal nutrient transporters in laying quails reared under heat stress (HS). One hundred and eighty laying Japanese quails (Coturnix coturnix japonica) were fed a basal diet or basal diet supplemented with either 2.5 or 5 g of taurine per kg of diet, and reared at either 22 ± 2 °C for 24 h/d (thermoneutral, TN) or 34 ± 2 °C for 8 h/d (HS) for 12 weeks. The quails reared under HS consumed less feed, produced less egg, and had lower dry matter, organic matter and crude protein apparent digestibilities compared with the quails reared under the TN condition (P = 0.001). However, increasing taurine concentrations in the diet improved feed intake and egg production (P = 0.001), but also the apparent digestibilities (P ≤ 0.027) in quails reared under HS. The greater doses (5 g/kg) of taurine resulted in more responses. The quails reared under HS had greater serum and liver MDA concentrations (P = 0.0001) which decreased with dietary taurine supplementations, particularly greater doses. The gene expressions of ileal PEPT1, EAAT3, CAT1, CAT2, SGLT1, SGLT5, GLUT2, and GLUT5 decreased under HS conditions (P = 0.001). However, supplementing taurine, in a dose-dependent fashion, to the diet of quails reared under HS resulted in increases in the gene expressions of the transporters (P < 0.05) except for CAT1. The results of the present work showed that taurine supplementation, particularly with greater doses (5 g/kg), to the diet of laying quails kept under HS acts as alleviating negative effects of HS, resulting in improvements in productive performance and nutrient digestion, and also upregulation of ileal nutrient transporters.     

Factors influencing response of flying Prostephanus truncatus to its male-produced aggregation pheromone

Abstract. The effects of age, sex, mating status, pre-exposure to pheromone, resource (diet) quality, and starvation on the response of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) to its male-produced aggregation pheromone were investigated.Age was an important factor determining the level of response to pheromone: young adults were more responsive than older adults.The suitability of the resource in which P.truncatus is present affected its dispersal tendency, but not its sensitivity to pheromone per se. Sex, mating status, brief prior exposure to pheromone, and starvation did not influence the response of the larger grain borer to pheromone.The orientation behaviour of the beetle is described, and it is proposed that the pheromone primarily functions as a 'suitable resource location and colonization signal'.     

Changes in calling behaviour and mating success in the European corn borer (Ostrinia nubilalis), caused by relative humidity

We examined the calling behaviour of O. nubilalis virgin females, held at three different constant conditions of relative humidity from the time of emergence through their sixth night of calling, as well as the incidence of mating over time at low or high relative humidity conditions. The mean age at which females initiated calling in their life was independent of relative humidity conditions, although more variable at low humidity. On successive nights of calling, fewer virgin European corn borer females called under low compared with high humidity conditions, and those that did began later in scotophase, had fewer calling bouts, and spent less time calling. These changes in the female prereproductive behaviour were reflected on the incidence of mating which, in the first two days following emergence, was significantly less at low than at high humidity conditions. The ecological significance of these results is discussed in relation with the susceptibility of O. nubilalis to desiccation.

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Résumé Nous avons étudié le comportement d'appel des femelles vierges d'Ostrinia nubilalis maintenues sous trois conditions constantes d'humidité relative, depuis l'émergence jusqu'à la sixième nuit d'appel, ainsi que l'incidence d'accouplement d'individus placés en milieu sec ou humide pour diverses périodes de temps. Les conditions d'humidité n'ont pas significativement affecté l'âge moyen auquel les femelles ont commencé à appeler au cours de leur vie, bien qu'il ait été plus variable à 53% h.r. Les nuits subséquentes, le comportement d'appel des femelles maintenues à basse humidité a débuté plus tard dans la nuit, s'est exprimé pour une période de temps plus courte avec moins de séquences d'appel que celui de leurs congénères placés en milieu humide, et la proportion de femelles en appel a toujours été plus faible à 53% h.r. Ces changements du comportement préreproducteur des femelles se sont répercutés sur l'incidence d'accouplement qui, les deux premiers jours suivant lémergence, a été significativement plus faible à basse humidité qu'elle ne l'a été en milieu humide. Ces résultats seront discutés en relation avec l'écologie de O. nubilalis et associés à sa susceptibilité à la dessication.

     

Environmental and genetic control of the larval diapause of the Southwestern corn borer, Diatraea grandiosella

ABSTRACT. The interaction of photoperiod and temperature in the regulation of the induction and termination of the larval diapause of the Southwestern corn borer, Diatraea grandiosella Dyar (Lepidoptera), was examined. A population originating from south-eastern Missouri had critical daylengths for diapause induction of about 15h 5min (ecological threshold) and llh (physiological threshold). The ecological threshold was more stable than was the physiological threshold at temperatures lower than 25°C. Above 25°C the diapause response was suppressed. The insect appears to measure photoperiods in a stationary manner since a stepwise increase or decrease in photoperiod did not affect the incidence of diapause. In the critical region of the photoperiodic response curve, a higher incidence of diapause was found among females than among males. Females entered diapause later than did males, but resumed active development earlier than males. The rate of diapause development was more temperature dependent than was the rate of diapause induction, yet it was also clearly under photoperiodic control. The temperature coefficient (Q₁₀) for this process was about 4. Several other factors including sex-linkage, age, and geographic adaptations are involved in controlling the rate of diapause development, even more so than they are in controlling diapause induction. In the laboratory, the intensity of diapause declined gradually without larvae being exposed to non-diapause inducing conditions. Incubation of field-collected larvae revealed that their sensitivity to diapause maintaining photoperiods had ended by January. Three generations of selection of a Mississippi population of D. grandiosella at 30°C and LD 12:12 led to the production of an essentially diapause-free strain and a diapause strain.