Mating frequency and reproductive success in an income breeding moth,Mnesampela privata

The frequency of mating in insects is often an important determinant of female reproductive output and male sperm competition. In Lepidoptera that provide male nutrients to the female when mating, it is hypothesized that polyandry may be more prevalent. This is thought to be especially so among species described as income breeders; that is, in species who do not derive all their nutrients for reproductive output entirely from the resources obtained during the larval stage. We selected the geometrid moth, Mnesampela privata (Guenée) (Lepidoptera: Geometridae), to examine this hypothesis further. We found this species was best characterized as an income breeder with female weight on emergence positively correlated with total egg load but not with the number of eggs laid. Further, in accord with income breeders, females emerged with a partially developed egg load and lifetime fecundity was positively correlated with the number of oviposition days. However, in the laboratory we found that incidence of repeated matings or polyandry was rare. When moths were paired singly over their lifetime, only 4% of mated females multiple mated. When females were paired with three males concurrently, female mating success increased from 60 to 81% with multiple mating among mated females increasing to just 15%. Dissection of wild caught M. privata found that polyandry levels were also low with a maximum of 16.4% of females collected at any one time being multiple mated. In accord with theory, mating significantly increased the longevity of females, but not of males, suggesting that females acquire essential resources from male ejaculates. Despite this, multiple mated females showed a trend toward decreasing rather than increasing female reproductive output. Spermatophore size, measured on death of the female, was not correlated with male or female forewing length but was negatively correlated with the number of fertile eggs laid and female longevity. Smaller spermatophore width may be related to uptake of more nutrients by the female from a spermatophore. We discuss our findings in relation to income breeding and its relationship to polyandry in Lepidoptera.     

Tarsal taste sensilla of the autumn gum moth, Mnesampela privata: morphology and electrophysiological activity

Mnesampela privata Guenée (Lepidoptera: Geometridae: Ennominae) is a native Australian geometrid that conducts considerable host assessment prior to ovipositing on its host plants, which belong to the genus Eucalyptus . The leaves of some of their hosts are covered with a particularly thick and waxy cuticle and we have shown that epicuticular waxes influence the oviposition preferences of females. This necessitates that M. privata has evolved specific chemosensory organs to assess the identity and perhaps even the quality of its hosts. In this work, we examined the morphology of tarsal taste sensilla and the sensitivity of their sensory neurones to a range of primary metabolites possibly influential on host assessment and oviposition. The ventral surface of the fifth tarsomere of females bear two parallel rows of up to eight sensilla, each loosely aligned with two parallel rows of five spines. Salts, sugars, and amino acids elicited phasi-tonic multicellular neuronal responses of variable magnitude and form. Two pairs of sensilla are closely apposed to the most distal spine in each row; the sensory neurones associated with these sensilla exhibited notably larger responses to alanine and serine compared with those of all other sensilla. The arrangement of the taste sensilla in close proximity to prominent tarsal spines is unique and could represent an adaptation that enables them to penetrate the wax layer and be brought into contact with primary metabolites present closer to the leaf surface.     

Oviposition by autumn gum moth (Mnesampela privata) in relation to Eucalyptus globulus defoliation, larval performance and natural enemies

Abstract 1 Eucalyptus globulus Labill. exhibited consistent intraspecific variation in oviposition choice by Mnesampela privata (Guenée) (Lepidoptera: Geometridae) in field surveys of host plants that had been designated, based on the prior season's defoliation levels, as resistant or susceptible to M. privata. At both field sites significantly fewer egg batches were found on resistant compared to susceptible trees. 2 In cage bioassays we demonstrated a significant oviposition preference by M. privata, with over two‐fold greater number of egg batches laid on foliage sprigs from susceptible compared to resistant trees. Despite differences in tree oviposition choice, we found no evidence in the field or the laboratory of adult females adjusting egg batch size in accordance to oviposition preference. 3 Caged larval survival, development times and pupal weight did not vary significantly between resistant and susceptible trees. Similarly, in a laboratory feeding experiment, neonates utilized resistant and susceptible foliage equally. 4 Larval mortality in the field attributed to natural enemies did not vary significantly between resistant and susceptible trees, nor did the percentage of Telenomus sp. parasitism of M. privata eggs within a batch and batches per tree. 5 Failure to associate either larval performance or natural enemy efficacy with the observed intraspecific variation in E. globulus susceptibility to M. privata oviposition indicates that some other unidentified factors drive the evolution of host selection for oviposition.     

The efficacy of high and low volume spray applications of Mimic® (tebufenozide) for managing autumn gum moth larvae Mnesampela privata (Lepidoptera: Geometridae) in eucalypt plantations

Abstract 1 The autumn gum moth Mnesampela privata (Guenée) (Lepidoptera: Geometridae, Ennominae) is a native moth that can outbreak, resulting in significant defoliation of plantation eucalypts in southern Australia. 2 Laboratory trials tested M. privata larvae for their dose–response to the ecdysone agonist, Mimic® 700 WP (a.i. 700 g/kg tebufenozide); ground and aerial field trials also tested its efficacy in eucalypt plantations. 3 The laboratory trials showed that there was no significant difference in mortality between larvae treated with 172 g Mimic® (120 g a.i)/ha and those sprayed with doses ranging from 86 to 3340 g Mimic®/ha. 4 Laboratory and field trials demonstrated that second instars were the most susceptible, with the most rapid response. However, second to fourth instars all reached 100% and fifth instars 90% mortality 3 weeks after aerial spraying at 120 g a.i./ha. 5 Aerial spraying an Eucalyptus globulus plantation with 120 g a.i. Mimic® at 20 L/ha caused 95% mortality of instars two to five, and 100% for instars two to four within 3 weeks after spraying. 6 Ground spraying to run‐off with 120 g a.i. Mimic®/ha reduced defoliation of E. grandis from between 67% to 80% for unsprayed trees to 0% defoliation for sprayed trees. 7 The window for effective management of M. privata larvae is 3–5 weeks, during first to third instar development. 8 Replacement of broad‐spectrum insecticides with the more target‐specific Mimic® should increase the biodiversity of plantations and therefore would be more environmentally friendly.     

Persistent effects of aerial applications of disparlure on gypsy moth: trap catch and mating success

In forest plots treated aerially with a plastic laminated flake formulation (Disrupt^® II) of the gypsy moth sex pheromone disparlure to disrupt gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), mating was monitored the year of treatment and 1–2 years after treatment to determine the effects of the treatment on suppression of trap catch and mating success. In the year of treatment, there was a greater than 95% reduction in trap catch and a greater than 98% reduction in mating success compared to controls. One year after treatment at a dosage of 37.5 g active ingredient (a.i.) ha^?1, trap catch was reduced by 46–56% and mating success was reduced by 60–79%. Both trap catch and mating success were significantly reduced compared to controls in plots treated 1 year previously at 15 g a.i. ha^?1. Trap catch, but not mating success, was significantly reduced 2 years after treatment at 37.5 g a.i. ha^?1. The efficacy of mating disruption (MD) treatments in the Slow‐the‐Spread of the Gypsy Moth program was significantly reduced 2 years compared to 1 year after treatment. No such reduction was observed in plots treated with aerial applications of Bacillus thuringiensis kurstaki. The higher apparent efficacy of MD treatments 1 year after application may result to some extent from the suppression of moth capture in pheromone traps from the persistent effects of the previous year's treatment.     

Development of pheromone-based mating disruption for control of the eye-spotted bud moth, Spilonota ocellana

The potential for pheromone-based mating disruption of eye-spotted bud moth (ESBM), Spilonota ocellana (Denis & Schiffermüller) (Lepidoptera: Tortricidae), in apple orchards in the Okanagan Valley of British Columbia was examined in small-plot trials. In a preliminary experiment, treatment of the orchard atmosphere with a 99:1 blend of Z8-tetradecenyl acetate (Z8-14:OAc) and Z8-tetradecenyl alcohol (Z8-14:OH) completely inhibited captures of male ESBM in pheromone-baited traps, but treatment with Z8-14:OAc alone did not. Therefore, all subsequent trials used the two-component blend as a disruptant. Mean catches of male ESBM in traps baited with 0.1, 1, 10, or 20 mg of 99:1 Z8-14:OAc and Z8-14:OH were significantly reduced (81–97%) in pheromone-treated plots relative to similar traps placed in control plots. In both control and treated plots, there was a significant positive relationship between trap bait dose and trap catch. In pheromone-treated plots, this suggests that high doses of trap baits over-ride the camouflage effect of disruption or overcome the effect of sensory adaptation and habituation. The number of virgin-female baited traps capturing at least one male ESBM was reduced by 96%, and mating of virgin females on mating tables was reduced by 95% in plots treated with the two-component pheromone. The total amount of Z8-14:OAc released from pheromone disruption dispensers during the latter field trials was estimated to average 6.4 g ha^-1 over 11 days or 26.4 mg ha^-1 h^-1. The low levels of Z8-14:OH released from disruption dispensers could not be estimated by GC analysis. Dispensers loaded with a 99:1 blend of Z8-14:OAc and Z8-14:OH were highly attractive to males in baited traps, indicating that they have the potential to induce false trail following.     

延迟交配对昆虫生殖行为的影响以及与性信息素防治害虫的关系

对鳞翅目昆虫延迟交配对昆虫生殖力、卵孵化率、交配成功率、成虫寿命等进行了总结。雌虫延迟交配降低雌虫的生殖力、卵的孵化率及与雄虫成功交配率,但可以延长雌虫寿命。雄虫延迟交配降低雌虫的生殖力、卵的孵化率、产卵时间,雄虫的精子质量下降但寿命有所增加。已发现延迟交配在迷向法中控制害虫起着重要的作用,对进一步认识迷向法中不同作用机理以及延迟交配在迷向法防治害虫中的潜力进行了探讨。     

Emergence and mating behavior of the oriental fruit moth Cydia molesta (Lepidoptera: Tortricidae) and its potential for reproduction

The Oriental fruit moth, Cydia molesta (Busck, 1916) (Lepidoptera: Tortricidae), is a key pest of fruit and is widely distributed around the world. There are important connections between its behavior and biology and its management in agriculture, but few studies have investigated the associations between adult behaviors and oviposition. In this study, adult emergence, mating, and reproduction were investigated under laboratory and field conditions. The ratio of females to males at eclosion was approximately 1:1. When one virgin female had access to one virgin male, 66% and 34% of the couples copulated just once and twice, respectively; and the infertility rate of eggs (21.39 ± 1.25%) did not vary daily. Males, given access to one new female daily, could copulate multiple times, whereas females seldom mated more than once, indicating a male-biased operational sex ratio, but mating status of the male parent had no effect on progeny egg reproduction. Also, the number of eggs that hatched by all female partners of a male was inversely proportional to copulation duration for the female laying the eggs for total female reproductive success; and the number of eggs laid by all female partners of a male was proportional to their number of matings for total male reproductive success. However, the total number of eggs that hatched did not significantly differ for eggs laid by a female given new virgin males daily for mating (17.75 ± 4.28) versus eggs laid by virgin females (19.17 ± 7.51) presented daily with a male that re-mated daily with the series of females. Therefore, our results showed that females engaged in mate choice and males engaged in mate competition, affecting egg production, a factor that may be used to enhance mating disruption technology against Cydia molesta.     

Gypsy moth mating disruption in open landscapes

1 Aerial applications of Disrupt II, a plastic laminated flake formulation containing a racemic form of the gypsy moth sex pheromone, disparlure, achieved > 99% reduction of mating among females on individual, isolated trees surrounded by an area cleared of trees.
2 These results support the use of mating disruption to eradicate isolated gypsy moth populations in open landscapes, such as parks, residential areas and commercial settings.
3 Mating success in both treated and untreated areas varied with the initial distance between males and females. When the initial distance between males and females was < 5 cm in an area receiving a dosage of 37.5 g of racemic disparlure per ha, mating success was reduced by 27% compared with a similar deployment in an untreated area. Mating was eliminated in areas treated at the same dosage when males and females were initially deployed 1 m apart but on separate trees.
4 This suggests that mating disruption may not be an effective tactic for gypsy moth eradication in cases where the infestation is concentrated on a small number of trees and males and females are in close proximity in space and time.     

Effects of SPLAT® GM sprayable pheromone formulation on gypsy moth mating success

Several integrated pest management programs rely on the use of mating disruption tactics to control insect pests. Some programs specifically target non‐native species, such as the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae). We evaluated SPLAT^® GM, a new sprayable formulation of the gypsy moth sex pheromone disparlure, for its ability to disrupt gypsy moth mating. The study was conducted in 2006, 2007, and 2008 in forested areas in Virginia, USA. Mating success of gypsy moth females was reduced by >99% and male moth catches in pheromone‐baited traps by >90%, in plots treated with SPLAT^® GM at dosages ranging from 15 to 75 g of active ingredient (a.i.) ha^?1. Dosage‐response tests conducted in 2008 indicated that SPLAT^® GM applied at a dosage of 7.5 g a.i. ha^?1 was as effective as a 15 g a.i. ha^?1 dosage.     

Life history and behavioural traits of Mnesampela privata that exacerbate population responses to eucalypt plantations: Comparisons with Australian and outbreak species of forest geometrid from the Northern Hemisphere

The larvae of the native Australian moth Mnesampela privata (Geometridae) sometimes defoliate plantation eucalypts, causing concern to industry. Typically, populations of M. privata maintain innocuous numbers in native forests, but outbreak populations can occur in plantations. Certain of the life history and behavioural traits of M. privata exacerbate population responses in simplified systems. Specifically, M. privata exhibits indiscriminate oviposition behaviour, for example, females oviposit upon leaves where conspecific egg clutches are already present. Combined with large egg clutches, this trait can lead to heavy exploitation of natal hosts. Complete defoliation of the natal tree necessitates that larvae disperse to undamaged hosts. In native forests, dispersing larvae would have a lower probability of locating a new host of suitable species and phenotype than they would in a plantation. Larval tolerance of a wide variety of species of Eucalyptus facilitates utilization of non‐natal eucalypts. A lower rate of encounter between larvae and natural enemies is achieved by means of leaf shelters and autumnal seasonal activity. Good dispersion by gravid females from plantations with large moth populations ensures that nearby plantations will be located. Given these characteristics, continued outbreaks of M. privata are likely in monospecific eucalypt plantations, especially when management practices reduce populations of natural enemies and overall vegetational complexity. However, because outbreaks only arise in plantations, population fluctuations of M. privata cannot be considered ‘self‐driven’. Hence, this moth is not a true eruptive species in the manner of other geometrids such as the autumnal moth (Epirrita autumnata autumnata) from Europe or the hemlock looper (Lambdina fiscellaria fiscellaria) from North America, but rather a gradient outbreak insect.     

The effects of body size on mating and reproduction in Brachinus lateralis (Coleoptera: Carabidae)

Abstract. 1. The causes and reproductive consequences of body size variation of Brachinus lateralis Dejean, a parasitic carabid beetle, were investigated.
2. Body size variation occurs within and between sites. Host size has a major influence on body size of the adult.
3. Fecundity is positively correlated with body size. Egg size is not correlated with body size.
4. Mating males tend to be larger than non-mating males. There is a positive correlation of body sizes in mating pairs.
5. Limited opportunity for host choice may maintain size variation despite the advantages of large size.
6. The non-random patterns of mating for a species without obvious intrasexual aggression suggest that subtle means of male-male competition or female choice may be important.     

Oviposition preference and neonate performance of Mnesampela privata in relation to heterophylly in Eucalyptus dunnii and E. globulus

Abstract

• 1 The autumn gum moth, Mnesampela privata, is an endemic Australian geometrid that utilizes a number of species within the genus Eucalyptus as hosts. Based on field observations, the moth is thought to be leaf‐type specific for juvenile as opposed to adult eucalypt foliage.
• 2 Laboratory binary choice assays of the oviposition preference of host novice M. privata confirmed that eggs were more likely to be laid upon juvenile rather than adult foliage of Eucalyptus dunnii and two subspecies of E. globulus. This oviposition preference was not influenced by differences in leaf size or adherence to leaves by ovipositing moths. The high specific leaf weights common to adult leaves were associated with reduced oviposition.
• 3 Although neonates fed on both juvenile and adult leaves of most of the trees studied, performance was greater on juvenile as opposed to adult foliage. Juvenile leaves typically had lower specific leaf weights and were nutritionally superior to their adult counterparts. Specific leaf weights above 0.236 mg/mm² (associated with low water, i.e. = 56.5%, and nitrogen, i.e. = 1.23%, contents) were associated with reduced larval performance. Younger adult leaves, those with lower specific leaf weights, allowed slightly greater larval consumption.
• 4 When ovipositing, this eucalypt‐specific moth discriminates between leaf types of its heterophyllous hosts in favour of types with the lowest specific leaf weight. Less tough leaf types, which are also higher in nitrogen, enable neonates to attain larger body weights.

     

Delayed mating reduces fecundity of blackheaded fireworm, Rhopobota naevana, on cranberry

This study examines the effects of delayed mating on two successive generations of blackheaded fireworm, Rhopobota naevana Hübner (Lepidoptera: Tortricidae), a pest of cranberry, Vaccinium macrocarpon Aiton (Ericaceae). The first (spring) generation produces eggs that hatch soon after oviposition, whereas the second (summer) generation produces mostly diapause eggs. Unmated female and male moths were placed together on the first, second, fourth, sixth, or eighth day after emergence. In the first generation, incidence of mating was greatest in the 1-, 2-, and 4-day treatments then declined as female survival decreased. In the second generation, incidence of mating was lowest in the 1-day treatment and greatest in the 2-, 4-, and 6-day treatments. Most second generation females in the 6- and 8-day treatments survived to mate. The mean oviposition period was 2.6 days for first generation females and 4.1 days for second generation females. Fecundity of singly mated females in both generations declined as age at mating advanced, but the pattern of decline differed between generations. First generation females that were mated on the first or second day laid more eggs than those mated on the fourth, sixth, or eighth day, and the number of infertile eggs increased as age at mating advanced. Fecundity of second generation females declined more gradually and the number of infertile eggs was greatest for females mated on the first, sixth, or eighth day. A consequence of the marked decline in fecundity due to mating delays in the first generation was that mean fecundity of the entire group of first generation females was ca. 13% less than that of the group of second generation females. On cranberry farms, pheromone-mediated mating disruption can prevent or delay mating of blackheaded fireworm. If the frequency of disrupted (prevented and delayed) matings is similar in the two generations, fewer eggs will be laid in the first generation than in the second.     

韭菜迟眼蕈蚊雄虫日龄对其交配能力和雌虫生殖力的影响

为了提高韭菜迟眼蕈蚊性信息素监控水平,本文在25℃、RH70%±5%、光周期L∶D=14∶10的条件下研究韭菜迟眼蕈蚊不同日龄雄虫的交配能力及其对雌虫生殖力的影响。结果表明,未交配雄虫平均寿命4.5d,雌虫4.2d,雌雄成虫的平均寿命无显著差异。雄虫一生最多可交配13次,且随着雄虫日龄增加,雌虫交配成功率逐渐减少。随着雄虫交配经历的增加,雌虫交配的时间延长,最长达97min。雄虫的日龄并不影响与之交配雌虫的产卵量和卵孵化率,但是雄虫的交配经历与雌虫的产卵量和卵孵化率相关,尤其当雄虫交配经历超过8次时,与之交配的雌虫的产卵量和卵孵化率显著下降。研究阐明了韭菜迟眼蕈蚊的生殖行为特征,为其性信息素应用提供了参考。     

Pheromone pre-exposure and mating modulate codling moth (Lepidoptera: Tortricidae) response to host plant volatiles

Abstract 1 Two codling moth Cydia pomonella kairomonal attractants, ethyl (E,Z)‐2,4‐decadienoate (pear ester) and (E)‐β‐farnesene, were tested in an insecticide‐sprayed apple orchard and an orchard treated for mating disruption with synthetic pheromone (E,E)‐8,10‐dodecadienol (codlemone). Male captures with pear ester were higher in the pheromone‐treated than in the insecticide‐treated orchard, whereas captures with (E)‐β‐farnesene were not different. Subsequent wind tunnel experiments confirmed that pre‐exposure to sex pheromone codlemone increased the behavioural response of codling moth males to pear ester. This supports the idea that male attraction to the plant volatile pear ester and sex pheromone codlemone is mediated through the same sensory channels. 2 Pear ester is a bisexual codling moth attractant and even captures of female moths were significantly increased in the pheromone‐treated orchard. In the laboratory wind tunnel, pheromone pre‐exposure had no effect on female response to pear ester, but significantly more mated than unmated codling moth females flew upwind towards a pear ester source. Differences in mating status in insecticide‐treated vs. pheromone‐treated orchards may thus account for the differences in female trap captures with pear ester. 3 These findings are important with respect to monitoring of codling moth with pear ester in mating disruption orchards. They also emphasize the importance of host plant volatiles in pheromone‐mediated mating disruption, which has been neglected to date.     

Effects of mating rate and delayed mating on the fecundity of Adoxophyes orana

Females of Adoxophyes orana F. v. R. (Lepidoptera: Tortricidae) could mate after one day, or after up to 7 days, after eclosion. It was recorded how many eggs per female were laid, had been fertilized and ultimately hatched. Mating rate was assessed by counting the spermatophores in a female.Egg production did not depend on mating rate, but proportion fertilization of eggs from females with three or more spermatophores was reduced. Delayed mating promoted longevity and changed the pattern of oviposition in time. No correlation was found between the proportion hatching of fertilized eggs and any of the other variables in the experiments.The data were introduced into a population model to compute the relation between fecundity and probability to mate.

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Effets du nombre d'accouplements et du retard de la date du premier accouplement sur la fécondité de Adoxophyes orana

Résumé Des femelles de A. orana F. v. R. (Lep., Tortricid.) ont eu la possibilité de s'accoupler le lendemain de leur émergence. Nous avons dénombré l'effectif d'oeufs pondus par chaque femelle, et calculé leur taux de fertilisation et d'éclosion. Les femelles ont été disséquées et les spermatophores comptés pour déterminer le nombre de copulations. La même procédure a été suivie avec d'autres femelles qui ont pu copuler librement jusquà leur mort, (leur longévité a été notée), mais avec une date du premier accouplement pouvant être retardée jusqu'à 6 jours après l'émergence.La production d'oeufs ne dépend pas du nombre de copulations, mais le taux de fertilisation des femelles avec 3 ou 4 spermatophores a été plus faible. Le retard de la date du premier accouplement augmente la longévité, mais réduit légérement le taux de fertilisation. La production d'oeufs était à peu près proportionnelle à la durée de la vie décomptée à partir du moment où la copulation était possible. Aucune corrélation n'a été mise en évidence entre la taux d'éclosion des oeufs fertilisés et les variables de l'habitat.Pour évaluer ces résultats et obtenir plus de connaissances sur les conséquences des copulations retardées, par exemple provenant de procédures d'interruption des copulations, les données ont été introduites successivement dans un modèle de populations pour établir la relations entre fécondité et probabilité d'accouplement.

     

Small plot mating disruption trials for tufted apple bud moth,Platynota idaeusalis, in Pennsylvania apple orchards

Mating disruption treatments for the tufted apple bud moth (TABM),Platynota idaeusalis (Walker), were tested in small plot trials in apple orchards in Pennsylvania. Treatments were evaluated by fruit injury and by capture of male TABM in traps baited with synthetic pheromone sources or virgin females. The TABM pheromone is a two component isomeric blend ofE-11-tetradecen-1-ol (E11-14:OH) andE-11-tetradecenyl acetate (E11-14:Ac). A 50∶50 ratio of these two components was used in standard monitoring septa and in mating disruption treatments released from either hollow fibers (‘fiber’) or PVC tubes (‘PVC’). Other pheromone blends tested included a 90∶10 ratio of E11-14: Ac and E11-14:OH (‘EAc’) and its reverse (‘EOH’), mixture ‘EAc’ with 30% of the Z-isomers (‘low AEc’), and a blend similar to the preceding with 2% Z9-12:Ac (‘generic’). These other blends were released from multi tube tape (‘tape’) or Shin-Etsu type rope (‘rope’) dispensers. Seasonal dispenser release rate in mg ha⁻¹ h⁻¹ was ca. 30 for the ‘rope’ dispensers, 14 for ‘PVC’ and 6 for ‘fiber’. ‘EAc-tape’ and ‘EOH-tape’ were equally effective in reducing catches of males in traps baited with synthetic lures and in traps baited with virgin females. Both treatments also reduced fruit injury. ‘EAc-rope’, ‘fiber’ and ‘PVC’ also were generally effective; whereas, the ‘low EAc’ and ‘generic’ treatments reduced trap capture less than 90% and did not reduce fruit injury. Dispenser density was positively correlated with reduction in trap capture for the ‘low EAc-rope’ and ‘genericrope’ treatments. Traps loaded with ‘fiber’ dispensers captured more male TABM than the other treatments in non-pheromone permeated environments. Trap capture of other tortricids was reduced in pheromone treatments. ‘EAc-rope’ and the ‘TABM’ treatments provided mean (s.e.) percent reduction in trap catch of 99.5 (0.4) and 42.9 (10.1), respectively, for the redbanded leafroller,Argyrotaenia velutinana (Walker), and 90.4 (6.8) and 90.4 (1.3), respectively, for the obliquebanded leafroller,Choristoneura rosaceana (Harris).     

Sprayable pheromone for controlling the North American grape berry moth by mating disruption

Abstract 1 Sex pheromone‐mediated mating disruption can be used to provide economic control of the North American grape berry moth in commercial vineyards. Controlled release devices that use a plastic tube or polymer to regulate the emission of pheromone have been registered for use in Canada for controlling this pest. These dispensers require manual application, whereas a newly developed microencapsulated formulation can be applied using a vineyard airblast sprayer. 2 The efficacy of 3M Sprayable Pheromone was compared with the efficacy of Isomate^® GBM pheromone dispensers and organophosphorus insecticide for controlling the grape berry moth during the 1997 and 1998 growing seasons. Two application schedules of sprayable pheromone were tested during 1997 and two formulations of sprayable pheromone were tested during 1998. The mating disruption efficiency of the pheromone treatments was compared using pheromone‐baited traps and the efficacy of the pheromone and insecticide treatments was compared by inspecting grape clusters for feeding injury caused by grape berry moth larvae. 3 The estimated mating disruption efficiency of the pheromone treatments ranged from 67 to 100%. There was no difference in the efficiency of the two application schedules of 3M Sprayable Pheromone during 1997. The estimated efficiency of Isomate^® GBM was greater than that of 3M Sprayable Pheromone during the first two flights of 1997. During 1998, the estimated efficiency of 3M Sprayable Pheromone and Isomate^® GBM was similar. 4 The average percentage of grape clusters with grape berry moth feeding injury was greater in the border than in the interior zone on 13 ocassions, and greater in the interior zone than in the border zone of experimental plots on six of the 72 occasions when clusters were inspected during the 2‐year study. 5 The average percentage of grape clusters with feeding injury was similar in plots treated with 3M Sprayable Pheromone, Isomate^® GBM and insecticide during both years of the study. There was no difference in feeding injury in plots treated with 3M Sprayable Pheromone and Isomate^® GBM, despite the greater estimated mating disruption efficiency of Isomate^® GBM. 6 The use of sprayable pheromone may have several operational and cost advantages compared with a hand‐applied dispensing system such as Isomate^® GBM.     

Reproductive performance of the hemlock looper,Lambdina fiscellaria,as a function of temperature and population origin

In a recent study of the hemlock looper (HL), Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae), long exposure of early‐diapausing eggs to high temperatures considerably reduced their ability to hatch. This finding raised the possibility that adults could also be negatively affected by increasing temperatures if they reproduced too early in the season in response to global warming. To investigate this hypothesis, newly formed HL pupae from three populations of eastern Canada ‐ Quebec (QC), Newfoundland (NL), and Labrador (LB) ‐ were submitted to four constant temperatures (10, 15, 20, or 25 °C) during pupal and adult development. The effect of population origin on HL reproduction was generally negligible. Mating probability was high at 15 and 20 °C (0.86 and 0.83, respectively), quite low at 10 °C (0.53), and even lower at 25 °C (0.38). Mating started earlier in the night and lasted longer as temperature decreased. Both productivity and absolute fecundity increased when temperature increased from 10 to 15 °C and then decreased slowly as temperature increased further. Over populations and temperatures, relative fecundity averaged 0.95, indicating that females had enough time to lay most of their eggs before they died. High temperatures had a deleterious effect on egg fertility: between 10 and 20 °C, relative fertility was about 0.90, but it dropped to 0.51 at 25 °C. The average proportion of fertile eggs declined from 0.88 in the first quarter of the egg‐laying period to 0.57 in the last quarter, suggesting lower sperm count or viability, or deterioration of the oocytes as the egg‐laying period progresses. Based on these findings, we argue that the production of an additional fifth instar among HL populations of southern origin can be viewed as an adaptive mechanism allowing adults to postpone reproduction or the egg‐laying period in order to mitigate the detrimental effect of high temperatures on their probability of mating successfully or that of laying fertile eggs.