Mating frequency in dispersing potato tuber moth, Phthorimaea operculella, and its influence on the design of refugia to manage resistance in Bt transgenic crops

Mating of potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), was investigated in relation to the dispersal of males in laboratory and field trials. The effect of stimulating the flight of males to light sources in a large cage on their mating ability was estimated for three age groups, and compared with similar estimates for confined moths. Although the mating of males declined with ages of up to 15 days, simulated dispersal had no effect on subsequent mating when the males were paired with virgin females. The dispersal of male moths was also categorised by the initial flight activity of untethered moths to a light source. Scores for poor, moderate, and good flight provided a repeatable measure of initial male flight activity, but the degree of activity was not related to their subsequent mating ability. In the field, virgin female potato tuber moths were tethered at various distances from the edge of isolated potato crops and then dissected to determine their mating status. Female mating frequency averaged 75% at the crop margin, remained above 50% up to 200 m, and then declined to 19% at 360 m from the margin. Derivation of the mating probability for an individual male potato tuber moth confirmed earlier work by other researchers that has indicated a tendency for dispersal prior to mating, and that males retain their ability to mate as they disperse from a crop. The influence of dispersal and mating on gene flow between crops, and its potential effects on refuge size required to minimise the development of resistance to Bt transgenic potato crops was examined.     

粘虫成虫在气流场中飞行行为的观察研究

通过改进悬吊测飞技术、室内风洞和野外雷达相结合的观测方法,研究了粘虫在气流场中的飞行行为特征及其与气流的关系。直筒风洞自由飞行观测的结果表明,粘虫蛾对气流有明显行为反应,表现为头部迎风起飞和迎风飞行的特性;在3.0～5.5 m/s风速下,有92%～94% 的个体可一次逆风飞行通过2 m长的风洞;当风速≥6.0 m/s时,有71.9%的蛾子沿螺旋状的飞行轨迹逆风通过风洞。环形风洞悬吊飞行测试的结果表明,粘虫可逆风飞行的最大风速为7.2 m/s;在风速≤4 m/s条件下,90%以上个体头部迎风飞行或头部朝向与风向成一定的夹角,侧逆风飞行。 雷达观测发现粘虫在空中迁飞过程中具有成层现象,并有较强的秋季回迁定向行为,其头部总是朝向西南;迁飞的最终位移与风向及风速大小有关,迁飞位移速度是飞行速度与风速的矢量和。     

风洞内粘虫飞翔行为与气流的关系

利用自制的昆虫飞翔实验风洞 ,系统观测了在风洞条件下粘虫在不同流速实验气流中的起飞行为与飞翔行为。结果表明 ,微风能刺激粘虫起飞 ,试虫表现明显的偏爱迎风 (或稍偏一点角度 )起飞的习性 ,飞翔时亦多采取迎风 (或稍偏一点角度 )的姿势。试虫在气流中的实际位移是昆虫飞翔位移与气流位移的矢量和。当气流速度小于 2 m/ s时 ,逆风向位移占多数 ;而气流速度为 3～ 4 m/ s时 ,94 .8%的试虫为顺风向位移。     

Role of moth ocelli in timing flight initiation at dusk

ABSTRACT. The role of ocelli in timing flight initiation of cabbage looper moths, Trichoplusia ni (Hübner) (Noctuidae), at dusk was studied under simulated sunset conditions using a multichannel actograph. The mean time of flight initiation was determined for control, sham (sham/occluded, sham ablated, unilateral ablated) and experimental (ocellus occluded, ocellus ablated moths). Ocellus occlusion delayed flight initiation on the first day following treatment but was less effective on the subsequent days. Ocellus ablation also delayed flight initiation on the first day, and also produced pronounced delays on subsequent days. In studies where the sunset was advanced 1 h, control sham ocellus occluded and unilaterally ocellus ablated moths responded to the advance, but bilaterally ocellus ablated moths did not. These results indicate that moths make use of input from the ocelli in determining the threshold light intensity for flight and in making adjustments to small light-phase changes.     

一日龄饥饿对粘虫成虫卵巢发育和飞行能力的影响

为了明确羽化后0～24 h (1日龄)饥饿处理对迁飞型粘虫Mythimna separata (Walker)生殖系统和飞行系统发育的影响,对1日龄饥饿处理后粘虫的卵巢发育级别、产卵前期、飞行肌和飞行能力进行了系统研究。结果表明, 1日龄饥饿对粘虫成虫卵巢发育级别、产卵前期、中胸背纵肌干重、飞行能力等均有显著的影响。饥饿后成虫卵巢发育级别显著高于对照,产卵前期显著短于对照。成虫中胸背纵肌干重从饥饿后96 h开始下降,至120 h时饥饿粘虫(5.1 mg)显著低于对照(5.86 mg)。成虫飞行能力从饥饿后96 h开始显著低于对照,此时饥饿处理粘虫蛾的飞行距离平均为22.03 km,飞行时间平均为4.07 h,显著低于同时期的对照粘虫的飞行距离(42.3 km)和飞行时间(7.99 h),尽管在饥饿后72 h内差异不显著。实验结果显示,1日龄饥饿可以显著抑制粘虫飞行系统的发育,加速飞行向生殖的转变。     

Mating disruption in Agrotis segetum monitored by harmonic radar

The long-range, pheromone-mediated, flight behaviour of male moths under natural and mating disruption conditions was monitored by means of harmonic radar. Individual male turnip moths, Agrotis segetum (Denis & Schiffermüller) (Lepidoptera: Noctuidae), tagged with radar transponders, were released and tracked in plots with or without disruptive doses of sex pheromone. In addition, male attraction to pheromone-baited traps and mating of calling females in treated and untreated plots was investigated. High doses of a four-component pheromone blend reduced trap catch by 79% and mating of females by 62% when compared with control plots in pre-radar experiments. Surprisingly, this effect was not associated with any pronounced differences in flight behaviour of males between a treatment and a control plot as revealed by harmonic radar recordings. In total, 20 flight tracks from a control plot and 22 flight tracks from a treatment plot were analysed. Moths could be followed for up to 77 min, corresponding to a track length of 7350 m. Mean ground speed ranged from 0.7 m s^–1 to 5.4 m s^–1. There was a strong trend (P = 0.06) for a greater number of male orientations to traps from downwind in the control field compared to the treatment field. Many flight tracks were fragmented due to radar shadow. Advantages and constraints using harmonic radar to study the pheromone-mediated flight behaviour of nocturnal moths are discussed.     

Factors influencing adult male Grapholita molesta dispersal in commercial Malus and Prunus host crops

The oriental fruit moth (OFM), Grapholita molesta (Busck) (Lepidoptera: Tortricidae), has been an economic pest of apples (Malus spp.) and peaches (Prunus spp.; both Rosaceae) in the eastern USA since the 1930s. Successful management of G. molesta with insecticides requires careful timing of these products based on sex‐pheromone trap captures of male moths. In Pennsylvania, apple and peach orchards are often planted adjacently. Factors such as trap distance from release points, host crop, and wind were considered in relation to male moth movement within and between hosts. Our practical objective was to understand male G. molesta dispersal within and between these two hosts to achieve better management. Recapture of moths decreased over distance; the majority of moths were recaptured 50–100 m from the release point regardless of crop type. Male G. molesta released into commercial apple and peach orchards were most likely to remain in the crop of release and to not exhibit host shifts over the season, even after peach fruit were harvested. Our analyses of wind direction data with respect to recapture showed that the likelihood of recapture was similar regardless of the orientation of the traps relative to the mean wind direction at peak flight times. The apple and peach host crops appeared to affect male G. molesta dispersal to the extent that wind in orchards affects their perception of pheromone. Crop effects were most likely due to the traps closest to the release points being in the same crop as the release points.     

Effects of age and mated status on flight potential of Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract The effects of ageing and female mated status on the flight potential of Helicoverpa armigera (Hübner), collected as larvae from a pigeonpea crop in southern India, were investigated using a tethered-flight technique. In non-mated moths fed sugar solution, from the first night after adult eclosion, the durations of both total and longest continuous flight per night increased up to night 4 and remained at this level until at least night 6. Ovarian maturation was rapid with 77% of unmated moths having commenced oviposition by the third night. On the basis of field evidence it is likely that most females would be mated by the third or fourth night, provided plants with nectar or sugary exudates were locally available. In successfully-mated females a 15-fold decrease in total flight duration and a 28-fold decrease in longest continuous flight duration was observed in contrast to non-mated females of similar age. As host plants suitable for adult feeding and oviposition were locally available during the time of feral adult emergence, synchronous pre-reproductive migration was unlikely to occur in the population studied.     

Flight duration and flight muscle ultrastructure of unfed hawk moths

Flight muscle breakdown has been reported for many orders of insects, but the basis of this breakdown in insects with lifelong dependence on flight is less clear. Lepidopterans show such muscle changes across their lifespans, yet how this change affects the ability of these insects to complete their life cycles is not well documented. We investigated the changes in muscle function and ultrastructure of unfed aging adult hawk moths (Manduca sexta). Flight duration was examined in young, middle-aged, and advanced-aged unfed moths. After measurement of flight duration, the main flight muscle (dorsolongitudinal muscle) was collected and histologically prepared for transmission electron microscopy to compare several measurements of muscle ultrastructure among moths of different ages. Muscle function assays revealed significant positive correlations between muscle ultrastructure and flight distance that were greatest in middle-aged moths and least in young moths. In addition, changes in flight muscle ultrastructure were detected across treatment groups. The number of mitochondria in muscle cells peaked in middle-aged moths. Many wild M. sexta do not feed as adults; thus, understanding the changes in flight capacity and muscle ultrastructure in unfed moths provides a more complete understanding of the ecophysiology and resource allocation strategies of this species.     

营养和幼期密度对棉铃虫飞翔能力的影响

采自棉花、玉米、花生、绿豆和芝麻5种作物上的棉铃虫Helicoverpa armigera(Hubner),其飞翔能力依次为：棉花和玉米>花生>绿豆和芝麻。对室内利用人工饲料、棉铃、棉蕾和棉叶饲养的棉铃虫吊飞表明,取食人工饲料和棉铃的个体的飞翔能力数倍于取食棉叶者。成虫体重越大,飞翔能力越强。获得补充营养个体的飞翔距离是无补充营养者的2倍左右。本试验还研究了食物质量对棉铃虫卵巢发育的影响,结果显示成虫期的补充营养明显影响幼期营养较差个体的卵巢发育进程。对不同幼虫密度下发育个体的吊飞则表明成虫的飞翔能力和幼期密度关系不大。鉴于较差的营养条件和较高的幼期密度并不导致成虫飞翔能力的增加,本文认为,棉铃虫的远距离运动是成虫对羽化阶段不良环境的行为反应。     

稻纵卷叶螟的飞行和再迁飞能力

稻纵卷叶螟Cnaphalocrocis medinalis (Guenée)可以通过连续几夜的飞行实现远距离迁移, 这种变幻莫测的再迁飞能力给稻纵卷叶螟的预测造成了极大的困难, 明确其迁飞行为参数是灾变预警的前提。为此, 利用飞行磨装置测定了稻纵卷叶螟成虫的飞行能力和再迁飞能力。结果表明: 在生殖隔离条件下, 稻纵卷叶螟不同日龄和不同性别的成虫的飞行能力间没有显著差异, 雌雄虫的平均飞行时间分别为156.94±103.19 min和147.71±111.38 min。根据吊飞的累计飞行时间(accumulative flight duration, AFD)可将稻纵卷叶螟种群划分为居留型(AFD<40 min)、迁飞型(40 min≤AFD≤130 min)和强迁飞型(AFD>130 min) 3种类型; 且3种类型的个体比率分别为46.1%, 27.3%和26.6%, 其中居留型平均累计飞行时间为11 min, 迁飞型为82 min, 强迁飞型为232 min。稻纵卷叶螟具有很强的再迁飞能力, 其种群作一次迁飞的个体比率都大于90%, 2次(夜)再迁飞的比率达70%以上, 一般可进行4~5次(夜)再迁飞, 最多可达9次(夜)。成虫的补充营养对再迁飞能力没有显著影响, 但蜜水可增强成虫的飞行能力。这些研究结果为稻纵卷叶螟的虫源分析和迁入区预测提供了基本参数。     

Wind as a factor influencing flower-visiting by Hadena bicruris (Noctuidae) and Deilephila elpenor (Sphingidae)

Abstract. 1. In a low-speed wind tunnel, male as well as female moths of Hadena bicruris responded to floral odours with positive anemotaxis. Hitherto, such orientation has only been demonstrated for male moths in response to pheromones.
2. H.bicruris had a maximum flight speed of 4.5–5.4ms^-1 and stopped its flower visiting at a wind speed of 2.5–2.8 m s^-1.
3. Deilephila elpenor had a similar maximum flight speed (4.5— 5.1 ms^-1), but it continued visiting flowers up to wind speeds of 3.0–5.0 ms^-1.
4. Apart from mechanical resistance during flight and flower visits, wind might have adverse effects on the energy budget and on evaporative water loss.     

黄地老虎飞行能力研究

黄地老虎Agrotis segetum是一种重要的农业迁飞性害虫,研究飞行生物学对明确其迁飞机理有重要意义。本项研究利用昆虫飞行磨系统对黄地老虎的飞行能力进行了测定。对实验室种群飞行能力的测定结果表明:1日龄成虫的飞行能力最弱;3日龄飞行能力最强,其24 h平均飞行时间、平均飞行距离和平均飞行速率分别达到12.16±0.74 h、48.94±3.40 km和3.76±0.12 km/h。雌蛾与雄蛾间的各项飞行参数均无显著差异,但处女成虫平均飞行距离和平均飞行速率均显著高于已交配个体。对渤海湾野外迁飞种群飞行能力的测定显示,早季节北迁个体和晚季节回迁个体的平均飞行时间和平均飞行距离无显著差异,但皆显著低于实验室种群。黄地老虎具有较强的飞行能力,日龄和交配是影响其飞行能力的关键因素。     

Dispersal of potato tuber moth estimated using field application of Bt for mark-capture techniques

A new mark-capture technique involving field applications of Bacillus thuringiensis Berliner (Bt) to study the dispersal of potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), was investigated as a tool to improve information on the potential impact of insect pest dispersal on crop infestation and insecticide resistance. The acquisition and persistence of Bt on moths were characterized and potential contamination of moths from naturally occurring Bts was examined. This mark-capture technique was developed to mark larger numbers of moths than had been previously achieved with laboratory marking using fluorescent dyes in mark-release-recapture experiments. Applications of commercial preparations of Bt to 0.3 and 1.0 ha potato fields were estimated to have marked ca. 50 000 moths in each experiment. Pheromone trap catches of potato tuber moths in the Bt-sprayed fields and in potato fields at distances of ca. 80, 200, 350, and 750 m were assayed for the Bt marker using selective microbiological media and identification of characteristic Bt crystal inclusions. Marking rates of moths were 78–100% in the sprayed fields and, compared with our previous mark-release-recapture studies, marking at ca. 200 m was increased by 15–18-fold to >3.0 moths per trap. This capture rate allowed the calculation of a dispersal curve that improved the reliability of estimates of movement at farm-scale distances. These estimates indicated that 10% of the population dispersed to 240 m in 3 days, and suggested that moths can potentially disperse throughout a typical potato-growing area in one growing season. This level of dispersal has implications for the spread and management of potato tuber moth populations, especially if insecticide resistance is present.     

棉铃虫飞翔的能源物质及消耗

研究结果表明棉铃虫Helicoverpa armigera(Hubner)初羽化个体的能源储备主要为甘油酯,1日龄成虫甘油酯和糖原的含量分别为每头3.6365mg和0.3658mg,通过成虫期的取食,二者的含量分别于羽化后4d和5d达到高峰(6.5707mg和2.3500mg)。对吊飞个体的测定表明甘油酯和糖原是棉铃虫飞翔的能源物质,蛋白质含量和飞行活动无明显的相关关系。4日龄成虫在飞行磨上吊飞66h,飞翔时间37.9943h,累积飞行216.8650km。累积消耗能量218.72J,其中甘油酯占85.87%,糖原占14.13%。     

粘虫飞行对生殖及寿命的影响

该文报道了粘虫Mythimna separata（Walker）成虫飞行后产卵、交配及寿命的研究结果。1日龄成虫飞行6 h、12 h、18 h、24 h后的产卵前期均显著短于对照的,其中飞行6 h、12 h的比对照的短2天以上,产卵量均比对照的高。对1～5日龄成虫分别飞行23.5 h后的研究结果表明,1日龄飞行的产卵前期和上述结果相一致。2～4日龄飞行的与对照的没有显著差异,但产卵量则随飞行日龄的延迟而逐渐减少。5日龄飞行的产卵前期显著延长,产卵量已不到对照的一半。所有经过飞行的成虫产卵高峰日比对照的早1天。不同日龄成虫飞行时间、距离与成虫产卵量的关系为：1～3日龄飞行时间、距离长的个体产卵量也高;但4～5日龄的成虫飞行时间与距离越长,其产卵量越少,表现出明显的卵子发生飞行拮抗症(oogenesis-flight syndrome)。除了5日龄飞行的成虫交配率有所下降以外,所有经过飞行的成虫产卵历期、交配率及寿命与对照的没有显著差异。最后,根据这些结果,对粘虫迁飞的起飞时期,迁飞在粘虫生殖、种群动态及成灾规律中的作用进行了讨论。     

The reproduction-flight syndrome and the inheritance of tethered-flight activity in the cotton-bollworm moth, Heliothis armigera

Abstract. To test the hypothesis that the flight activity of Heliothis armigera (Hiibner) (Lepidoptera: Noctuidae) conforms to the 'oogenesis-fiight syndrome', female moths from India and Malawi were flight tested on nights 2, 4 and 6 after eclosion, using a tethered-flight technique. Maximum flight activity in the Indian strain occurred on night 2, that of the Malawian strain was not significantly different on the three nights of flight. This difference is explained by the Indian females reaching reproductive maturity c . 48 h before the Malawian females. The existence of a 'reproduction-flight syndrome' was confirmed by flight testing males and females of different maturity status on the fourth night after eclosion. Immature moths flew significantly more than did either mature-virgin or mature-mated moths. The inheritance of tethered-flight activity in a late-maturing line of Malawian H. armigera was investigated. Significant estimates of heritability, by offspring on mid-parent regressions, were obtained for both the total flight time (0.39 æ 0.083) and the longest flight (0.15 ± 0.058). The significance of such tethered-flight data to noctuid migration in the field is discussed, and the conclusion drawn that the current experimental design does not index migratory flight satisfactorily.     

Disruption of the odour-mediated mating behaviour of Plodia interpunctella using high-frequency sound

Abstract Indian meal moths, Plodia interpunctella Hübner (Lepidoptera: Pyralidae), have ears which are sensitive to high‐frequency calls produced by echolocating, insectivorous bats. The influence of artificially generated, high‐intensity, ultrasound signals (25 kHz, 106 dB SPL at 1 m distance) on different parameters involved in the odour‐mediated mating behaviour of this species and its potential use in population control was investigated. All moths flying towards olfactory cues in flight tunnel experiments reacted strongly to a 1 s ultrasound pulse by cessation of flight and falling out of the odour plume. The source contact proportion of both male moths orienting towards the female‐produced sex pheromone and of mated female moths orienting towards an oviposition cue was reduced by 40%, compared to unexposed moths. Calling females responded to the sound by retraction of the ovipositor or by falling to the ground. Long‐term exposure to repetitive pulses of ultrasound suppressed female calling by up to 27%. Furthermore, mating in plastic tents was disrupted by up to 58% in ultrasound‐treated tents using different sound regimens, compared to control tents. The results are discussed in relation to the potential use of ultrasound technology for the population control of pyralid stored product pests.     

Laboratory evaluation of flight activity of the common cutworm, Spodoptera litura (Lepidoptera: Noctuidae)

Abstract  The flight activity of Spodoptera litura in tethered conditions is evaluated using a computer-mediated flight-mill in the laboratory. The 3–4-day-old moths fly longer and farther than those of other ages. Male and female moths exhibit similar flight activity. Mating status does not influence the flight duration and distance of 2-day-old females. However, these two flight parameters with a 6-day-old mated female is significantly lower than that of unmated ones. The optimum temperature for flight ranged from 16–24°C, whereas the optimum RH ranged from 60%–100%. During 72-h period, the total flight duration and distance of 1-day-old male and female moths were 19.6 h (± 5.8) and 83.3 km (± 28.4), and 24.0 h (± 7.0) and 105.4 km (± 37.4), respectively. These results indicate that S. litura has a great potential to undertake long-distance migratory flights.     

甘蓝夜蛾Mamestra brassicae Linnaeus飞行能力研究

【目的】测定日龄、性别、交配等因素对农业迁飞性害虫甘蓝夜蛾Mamestra brassicae Linnaeus飞行能力的影响,为其迁飞行为研究和异地测报提供理论依据。【方法】在气温为(24±1)℃、相对湿度为75%±5%的实验室环境下,利用飞行磨系统对甘蓝夜蛾实验室种群1~5日龄未交配个体、已交配的3日龄个体以及野外迁飞种群分别进行连续24 h吊飞测试,记录其累计飞行时间、累计飞行距离、平均飞行速率等参数。【结果】甘蓝夜蛾实验室种群的飞行能力随日龄增长而变化,初羽化时即具有较强的飞行能力,2~3日龄达到峰值,4~5日龄的飞行能力显著下降;雌性甘蓝夜蛾的飞行能力强于雄性甘蓝夜蛾;交配的甘蓝夜蛾平均飞行速率显著小于处女甘蓝夜蛾,但二者的平均飞行时间和飞行距离均无显著差异。此外,渤海湾迁飞种群中晚季节南迁种群的飞行能力显著强于早季节北迁种群和过渡种群。【结论】日龄和交配状态是影响甘蓝夜蛾飞行能力的关键因素。