Ovarian response to resource availability in female Rhagoletis indifferens

Fitness trade‐offs in behavioural ecology theory suggest that the costs associated with dispersal can impact reproductive output, but evidence of dispersal‐reproduction trade‐offs is often lacking. We present evidence of Rhagoletis indifferens Curran (Diptera: Tephritidae) developing its egg load in response to host availability [Prunus avium L. (Rosaceae)] and link this to our previous work on flight behaviour through the common methodology of these two studies. We replicated the study design from the flight mill experiment, such that females were maintained in one of six possible treatments combining two factors: social interactions (crowded vs. isolated) and resources (food = food only; leaf = food + leaf; and cherry = food + leaf + fruit), and then dissected the females to determine egg load. Egg counts varied significantly with ‘crowded’ females and those in the ‘cherry’ resource treatments producing the most mature eggs. Although the average mature egg count for females from the ‘leaf’ and ‘food’ resource treatments was similar, these two groups differed in the proportion of females that produced no mature eggs at all. No significant interaction terms between the factors tested were generated. We conclude that the effect of social interactions and resources on the maturation of eggs is additive in R. indifferens. These results support those of an earlier flight mill experiment and provide evidence that egg load may trade off with dispersal ability in R. indifferens.     

Effect of sex,age and morphological traits on tethered flight of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) at different temperatures

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a pest of fruit and vegetable production that has become established in 42 countries in Africa after its first detection in 2003 in Kenya. It is likely that this rapid expansion is partly due to the reported strong capacity for flight by the pest. This study investigated the tethered flight performance of B. dorsalis over a range of constant temperatures in relation to sex and age. Tethered flight of unmated B. dorsalis aged 3, 10 and 21 days was recorded for 1 h using a computerized flight mill at temperatures of 12, 16, 20, 24, 28, 32 and 36 °C. Variations in fly morphology were observed as they aged. Body mass and wing loading increased with age, whereas wing length and wing area reduced as flies aged. Females had slightly larger wings than males but were not significantly heavier. The longest total distance flown by B. dorsalis in 1 h was 1559.58 m. Frequent short, fast flights were recorded at 12 and 36 °C, but long-distance flight was optimal between 20 and 24 °C. Young flies tended to have shorter flight bouts than older flies, which was associated with them flying shorter distances. Heavier flies with greater wing loading flew further than lighter flies. Flight distances recorded on flight mills approximated those recorded in the field, and tethered flight patterns suggest a need to factor temperature into the interpretation of trap captures.     

Commercial Yellow Sticky Strips more attractive than yellow boards to western cherry fruit fly (Dipt., Tephritidae)

Bright yellow sticky rectangles made of paper boards were previously identified as the most effective traps for capturing western cherry fruit fly, Rhagoletis indifferens Curran (Dipt., Tephritidae). However, no data on the effectiveness of commercial sticky yellow plastic traps against R. indifferens have been reported. In tests conducted in sweet cherry trees [Prunus avium (L.) L.] in Washington state (USA) using ammonium carbonate as the chemical lure, commercial plastic ‘Yellow Sticky Strips’ made of translucent high‐impact polystyrene captured ~two or three times more flies than commercial sticky yellow‐folded Pherocon^® AM and Alpha Scents boards. Yellow Sticky Strips also minimized captures of non‐target flies and bees per surface area compared with Pherocon^®AM and/or Alpha Scents boards. Trap size and adhesive type were not factors for greater catches of R. indifferens. However, more flies were caught on the shade‐facing side of Yellow Sticky Strips, which was brightly illuminated, than on the shade‐facing side of boards, which was darker, suggesting differential light passage was a factor. The Yellow Sticky Strips could be very useful for monitoring R. indifferens in detection programmes and based on the results of this study can replace yellow boards. They are also useful because they are relatively unattractive to non‐target insects.     

Mortality of Rhagoletis indifferens exposed to hydrolyzed protein baits and spinosad in the absence and presence of yeast extract

Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is the major quarantine pest of sweet cherry, Prunus avium (L.) L. (Rosaceae), in the Pacific northwest of the USA and in British Columbia in Canada. Although spinosad bait (GF‐120 NF Naturalyte® Fruit Fly Bait) is used for the control of R. indifferens in this region, the effects of alternate food sources on fly responses to this bait have not been studied. In this study, experiments were conducted to determine mortalities of flies exposed to hydrolyzed protein baits in the presence of sugar only and sugar + yeast extract food. All baits contained Entrust® (termed ‘spinosad alone’). When flies were exposed to GF‐120 with or without added ammonia compounds (uric acid, ammonium acetate, and ammonium carbonate) for 48 h, mortalities were higher in the presence of sugar only than in the presence of sugar + yeast extract, but when flies were exposed to spinosad alone, mortalities were similar in presence of either of the two foods. In another experiment comparing GF‐120, Nu‐Lure, Mazoferm, Baker's yeast extract, and spinosad alone, mortalities in the GF‐120, Mazoferm, and Baker's yeast extract treatments were higher in the presence of sugar only than in the presence of sugar + yeast extract, but in the Nu‐Lure and spinosad alone treatments, mortalities were similar in the presence of either of the two foods. Overall results suggest that the indirect effects of yeast extract food on mortality are dependent on bait type and that mortalities caused by spinosad alone and baits are similar. Nu‐Lure and spinosad alone may have an advantage over other treatments for fly control, because their effects do not appear to be affected by the presence of nitrogenous food.     

Investigations of the oogenesis-flight syndrome inAnthonomus grandis (Coleoptera: Curculionidae) using tethered flight tests

This paper investigates the relationship between oogenesis and flight duration and the use of tethered flight as an indicator of tendency to migrate inAnthonomus grandis grandis Boheman (Coleoptera: Curculionidae), the boll weevil. When boll weevils were flown to exhaustion in tethered flight tests, many flew between 2 and 3 h, with several flying more than 4 h. To test the validity of the tethered flight test as an indicator of tendency to migrate, comparisons of mean flight duration were made between boll weevils trapped in pheromone traps far from any cultivated cotton and those trapped at the edge of heavily infested, flowering cotton fields. There was a significant difference in mean flight time between the two groups, supporting the assumption that long-duration tethered flight in the laboratory reflects the tendency to make long-distance flights in the field. Groups of weevils of different ages were killed after flight testing, and the degree of ovarian development and fat body status were determined and related to duration of tethered flight. Insects with undeveloped or partially developed ovaries were the most likely to make long flights. Weevils with ovaries bearing chorionated eggs made very few long flights. Flight duration was positively correlated with degree of fat body development. In contrast, there were no significant differences in the degree of ovarian development with fat body status. We conclude from these experiments thatA. grandis grandis is capable of long-distance flight, that this species displays some behavioral and physiological characteristics typical of many insect migrants including an oogenesis-flight syndrome, and that a tethered flight test is an appropriate means of measuring migratory tendency in this species.     

Flight Performance of <Emphasis Type="Italic">Agrilus planipennis</Emphasis> (Coleoptera: Buprestidae) on a Flight Mill and in Free Flight

Computer-monitored flight mills were used to record the flight performance of the emerald ash borer, Agrilus planipennis Fairmaire. Flight performance of fed and unfed, and mated and unmated beetles of both sexes were recorded and compared. Mated females flew further per day and longer than unmated females or males. Mated females that were allowed to feed between flight periods flew an average of 1.3 km/day for four days; 10% flew more than 7 km/day. Measurements of free-flight speed using a mirror and a high-speed camera were used to calibrate the flight mill results, permitting absolute estimates of flight performance to be made. Free-flight speeds were approximately three times the speeds recorded by the flight mills. The median corrected distance flown by mated females was >3 km with 20% flying >10 km and 1% flying >20 km. The flight performance of mated females suggests a considerable capacity for range expansion by this invasive species. The implications for quarantine and control are discussed.     

Variability in response specificity of apple, hawthorn, and flowering dogwood-infesting Rhagoletis flies to host fruit volatile blends: implications for sympatric host shifts

Rhagoletis pomonella Walsh (Diptera: Tephritidae) originating from domesticated apple (Malus pumila), hawthorn (Crataegus mollis) (Rosaceae), and flowering dogwood (Cornus florida) (Cornaceae) were tested sequentially in flight‐tunnel assays to volatile blends previously identified from the three fruit types. The majority of flies flew to odor sources containing their natal blend (68–83%). Some flies from each fruit type also flew to non‐natal fruit blends (11–39%), but of these non‐natal responders the vast majority were flies that responded to their natal blend as well. The results indicate that individual flies within R. pomonella populations infesting different host types have different degrees of specificity with respect to discriminating among fruit volatile blends, and that a moderate proportion of apple, hawthorn, and dogwood flies (10–30%) are broad responders, with the capacity to recognize and orient to more than one blend. The observed variability in response specificity could facilitate sympatric shifts to new host plants.     

Detection of Rhagoletis indifferens (Dipt., Tephritidae) larvae using brown sugar flotation and hot water methods

The brown sugar flotation and hot water methods are accepted procedures for detecting larval western cherry fruit fly, Rhagoletis indifferens Curran, in sweet cherry [Prunus avium (L.) L.] and could be included in a systems approach, a combination of all steps involved in cherry production, for showing the absence of larvae in fruit. The methods require crushing cherries and then submerging them in brown sugar solution or hot water to extract the larvae. Larvae are visually detected when they float to the surface of the brown sugar solution or sink in the hot water. The objective of this study was to test the efficacy of these two methods. Both methods detected at least one larva in all 288 moderately to heavily infested cherry samples. The brown sugar flotation and hot water methods detected 89.6–94.7% and 83.0–85.9% of total larvae, respectively, from cherry samples on each of three dates. Significantly higher percentages of 1st instars were detected using the brown sugar than hot water method on two dates, of 3rd instars on one date and of total larvae on two dates. Percent detection of 3rd instars was higher than that of 1st instars using both methods. For both methods, greater percentages of split whole cherries with seeds and non‐split cherries had larvae than split whole cherries with no seeds and halved cherries. Results show that both methods were equally efficacious in detecting the presence of R. indifferens larvae in cherry samples, but brown sugar flotation was more efficacious than the hot water method in detecting a higher percentage of total larvae present and could be integrated into a systems approach for R. indifferens.     

适用于蚜虫等微小昆虫的飞行磨系统

介绍了一套采用计算机进行控制和数据采集的适用于蚜虫等微小昆虫的飞行磨系统。该系统能同时对32头昆虫进行飞行测试,并对测试数据进行自动分析处理。利用该飞行磨系统对不同日龄禾缢管蚜的飞行能力进行了初步测试。结果表明,禾缢管蚜在第1至第5日龄的飞行能力最强,明显高于第7和第9日龄。平均飞行时间在各日龄之间差异不显著,但平均飞行速度随日龄的增加而逐渐降低。本文对飞行磨结构、数据采集接口板电路原理和软件流程设计等方面均进行了较为详细的介绍。并简要介绍了不同日龄禾缢管蚜的飞行能力测试结果。对开展微小型昆虫的飞行行为学研究具有较为重要的参考价值。     

Genetic structure of cherry fruit fly (Rhagoletis cingulata) populations across managed,unmanaged, and natural habitats

The cherry fruit fly (CFF), Rhagoletis cingulata Loew (Diptera: Tephritidae: Trypetini), is endemic to eastern North America and Mexico, where its primary native host is black cherry [Prunus serotina Ehrh. (Rosaceae)]. Cherry fruit fly is also a major economic pest of the fruit of cultivated sweet (Prunus avium L.) and tart (Prunus cerasus L.) cherries. Adult CFF that attack wild black cherry and introduced, domesticated cherries in commercial and abandoned orchards are active at different times of the summer, potentially generating allochronic isolation that could genetically differentiate native from sweet and tart CFF populations. Here, we test for host‐related genetic differences among CFF populations in Michigan attacking cherries in managed, unmanaged, and native habitats by scoring flies for 10 microsatellite loci. Little evidence for genetic differentiation was found across the three habitats or between the northern and southern Michigan CFF populations surveyed in the study. Local gene flow between native black cherry, commercial, and abandoned orchards may therefore be sufficient to overcome seasonal differences in adult CFF activity and prevent differentiation for microsatellites not directly associated with (tightly linked to) genes affecting eclosion time. The results do not support the existence of host‐associated races in CFF and imply that flies attacking native, managed, and unmanaged cherries should be considered to represent a single population for pest management purposes.     

Flight behaviour of the bird cherry aphid, Rhopalosiphum padi

Abstract Seasonal winged forms of the bird cherry aphid, Rhopalosiphum padi L., were flown in an automated flight chamber. During their maiden flights, autumn migrants (gynoparae) had a greater initial rate of climb than summer (exules) and spring migrants (emigrants). Autumn migrants, presented with a laterally-positioned green-illuminated target for 2.5 s during each minute of flight, flew for a longer period before responding to the target (110 min) than summer migrants (36 min), while spring migrants responded after an intermediate time (72 min). This period is equivalent to the migratory phase of flight. The summer migrants were maximally responsive to targets illuminated by green monochromatic light (X, 555 nm). Targets illuminated with ultraviolet (γλ 360 nm) were attractive during the migratory and green-responsive phases of flight, but infrared (γλ700 nm) wavelengths were not attractive. The results are discussed with respect to aphid behaviour in the field.     

Brugia pahangi: effects upon the flight capability of Aedes aegypti.

Aedes aegypti mosquitoes were adversely affected by infections of the filarial worm Brugia pahangi. Infected mosquitoes flew significantly shorter distances and showed marked reductions in total flight time during 24-hr flight mill tests compared to uninfected controls. Total flight range and duration flown by infected mosquitoes remained relatively constant throughout the infection process, while control mosquitoes flew further and longer with increasing time after their blood meal. Furthermore, a significantly greater number of infected mosquitoes either died or were rendered incapable of flight. Of flying and nonflying mosquitoes with 6-day-old or older infections dissected for parasite burdens, the nonflying group contained significantly more worms. Results of this study indicate that developing filarial larvae within this mosquito vector reduce its ability to survive and to transmit its infection by reducing its flight capabilities. Conclusions from this study relate only to A. aegypti homozygous for the gene fm which is fully susceptible to this filarial parasite.     

Morphological variation associated with dispersal capacity in a tree‐killing bark beetle Dendroctonus ponderosae Hopkins

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Size‐dependent insect flight energetics at different sugar supplies

Under most circumstances, large body size confers a higher fitness and is positively selected, whereas selection against large size is empirically poorly documented. Physiologically, according to the ¾ power law, larger animals have lower relative but higher absolute energy demands, such that large body size may become disadvantageous, particularly under fast locomotion in food‐limited environments. After a period of initial feeding on different sugar concentrations, we investigated size‐dependent energy content (reserves) at baseline and of females unflown (i.e. resting) or flown for 18 h in two (replicate) insect species: the yellow dung fly Scathophaga stercoraria and the yellow fever mosquito Aedes aegypti. Tethered adults of various sizes were tested in a flight mill. In both species, teneral glycogen, sugar, and lipid content increased with sugar availability, and isometrically or even hyper‐allometrically (slope > 1) with body size. Activity treatment also revealed the expected consumption effects. Both species increased their flight distance with sugar supply, although only larger mosquitoes flew longer. Crucially, larger females of both species disproportionately exhausted more glycogen and sugars (but not lipid) during flight. The mosquitoes appeared to adjust their flight more finely to their size‐dependent energy reserves at all sugar availabilities, whereas, in the dung flies, size‐dependent energy demands were detectable only with a low but not with an overly high sugar supply. Although we found a greater absolute and relative locomotory energy demand for the larger flies, which is in agreement with interspecific patterns in insects, this was (more than) compensated by their greater baseline energy reserves, resulting in the greater net flying capacity of larger individuals. Consequently, we found no evidence for energetic mechanisms limiting the performance of large flying insects under food limitation. The differences between the two species presumably relate to mosquitoes inherently being long distance flyers and dung flies being short distance flyers. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Sex,life history and morphology drive individual variation in flight performance of an insect parasitoid

1. The movement of organisms can be driven by multiple factors and has implications for fitness and the spatial distribution of populations. Insects spend a large proportion of their adult lives foraging by flying for resources; however, their capability and motivation to move can vary across individuals. 2. The aims of this study were to examine interindividual and sex differences in flight performance and flight characteristics, using a flight mill bioassay, in Megarhyssa nortoni (Hymenoptera; Ichneumonidae), a parasitoid of the invasive woodwasp Sirex noctilio (Hymenoptera: Siricidae), one of the most important pests of pine afforestation worldwide. We also assessed the influence of morphological traits in combination with sex on flight and explored the cost of flight on longevity and mass loss. 3. The results show a difference between sexes in flight characteristics and performance. Females show greater total distance flown than males, and have a better capacity to undergo sustained flight. Sexual size dimorphism was also found and it was noted that size positively affects distances travelled. Females have a longer life span than males, yet no differences were noted in longevity within sex between individuals that did not fly and those that flew. Age did not influence flight performance of females or impacted on post‐flight longevity. Females lost less body mass than males even after flying longer distances. 4. These results suggest that sex‐specific behaviours probably govern flight abilities together with (and not only because of) morphological traits. The paper discusses sex‐specific life‐history strategies in parasitoids and their implications for biocontrol programmes.     

Water balance in Rhodnius prolixus during flight: Quantitative aspects of diuresis and its relation to changes in haemolymph and flight-muscle water

The amount of water voided by male Rhodnius prolixus which were flown to exhaustion varied from 0 to over 10% of the initial live weight. It accounted for nearly all of the body water lost during the flight period. Simultaneous measurements on the loss of haemolymph water and an estimate of the amount of faecal water in the excreta indicated that the source of the voided water was primarily the haemolymph. The total water content of the flight muscles changed very little in insects which flew to exhaustion. It is concluded that, despite the diuresis and loss of water, and the considerable reduction in haemolymph volume, dehydration of the flight muscles of male R. prolixus does not occur during these flight periods, and is not a factor contributing to ‘exhaustion’. The possibility that insufficient haemolymph is a factor limiting the duration of flight is discussed.     

Characterization of novel microsatellites and development of multiplex PCR for large‐scale population studies in wild cherry,Prunus avium

Primers were developed for 14 microsatellite or simple sequence repeat (SSR) loci identified from a Prunus avium‘Charger’ genomic DNA library. In a survey of 16 wild cherry accessions 10 of the loci revealed polymorphisms of between two and six alleles. The remaining loci were found to be monomorphic. Seven polymorphic loci identified in this study and four polymorphic loci previously reported in sweet cherry were mapped and found to be unlinked. Two multiplex polymerase chain reactions (PCR) were optimized to enable the characterization of all 11 unlinked, polymorphic SSR loci.     

Tethered flight of the potato moth, Phthorimaea operculella

ABSTRACT. The effects of sex, age and mated state on average flight speed, duration and distance were determined for potato moths, Phthorimaea operculella (Zeller) (Lepidoptera, Gelechiidae), tethered to flight mills. Moths were classified as non-fliers (NFs), good-fliers (GFs) and remaining-fliers (RFs) on the basis of their performance over the first two flights. Some moths flew for over 5 h non-stop, while others tethered overnight flew between 20 and 30 km. Speed, duration and distance flown were greater during the first flight. First flight duration and distance flown by females decreased with age, whereas no trend was evident for males. Mated males and females flew slower first flights with increasing age, whereas virgin moths showed no marked trend. The analysis of fliers and NFs revealed that GFs were heavier than both RFs and NFs, GFs were faster than RFs, the percentage of NFs increased with age especially for mated females, and the percentage of GFs decreased with age. Age and mated state are important factors influencing flight performance especially for female moths. The relevance of these results to the field situation and the possible application of tethered flight to tests of potato moth quality are discussed.     

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。     

Differences in body size and egg loads of Rhagoletis indifferens (Diptera: Tephritidae) from introduced and native cherries

The western cherry fruit fly, Rhagoletis indifferens Curran, infests introduced, domesticated sweet [Prunus avium (L.) L.], and tart cherries (Prunus cerasus L.) as well as native bitter cherry, Prunus emarginata (Douglas) Eaton. Bitter cherries are smaller than sweet and tart cherries and this could affect various life history traits of flies. The objectives of the current study were to determine 1) if body size and egg loads of flies infesting sweet, tart, and bitter cherries differ from one another; and 2) if any observed body size differences are genetically based or caused by the host fruit environment. Pupae and adults of both sexes reared from larval-infested sweet and tart cherries collected in Washington and Montana were larger than those reared from bitter cherries. In addition, flies of both sexes caught on traps in sweet and tart cherry trees were larger than those caught in bitter cherry trees and females trapped from sweet and tart cherry trees had 54.0-98.8% more eggs. The progeny of flies from naturally-infested sweet and bitter cherries reared for one generation in the laboratory on sweet cherry did not differ in size. The same also was true for progeny of sweet and bitter cherry flies reared in the field on bitter cherry. The results suggest that the larger body sizes of flies from sweet and tart cherries than bitter cherries in the field are caused by host fruit and not genetic factors.