Arctiid moth ensembles along a successional gradient in the Ecuadorian montane rain forest zone: how different are subfamilies and tribes?

Aim We examined changes in the species diversity and faunal composition of arctiid moths along a successional gradient at a fine spatial scale in one of the world's hot spots for moths, the Andean montane rain forest zone. We specifically aimed to discover whether moth groups with divergent life histories respond differentially to forest recovery. Location Southern Ecuador (province Zamora‐Chinchipe) along a gradient from early successional stages to mature forest understorey at elevations of 1800–2005 m a.s.l. Methods Moths were sampled with weak light traps at 21 sites representing three habitat categories (early and late succession, mature forest understorey), and were analysed at species level. Relative proportions were calculated from species numbers as well as from specimen numbers. Fisher's α was used as a measure of local diversity, and for ordination analyses non‐metric multidimensional scaling (NMDS) was carried out. Results Proportions of higher arctiid taxa changed distinctly along the successional gradient. Ctenuchini (wasp moths) contributed more strongly to ensembles in natural forest, whereas Lithosiinae (lichen moths) decreased numerically with forest recovery. Arctiid species diversity (measured as Fisher's α) was high in all habitats sampled. The three larger subordinated taxa contributed differentially to richness: Phaegopterini (tiger moths) were always the most diverse clade, followed by Ctenuchini and Lithosiinae. Local species diversity was higher in successional habitats than in forest understorey, and this was most pronounced for the Phaegopterini. Dominance of a few common species was higher, and the proportion of species represented as singletons was lower, than reported for many other tropical arthropod communities. NMDS revealed a significant segregation between ensembles from successional sites and from forest understorey for all larger subordinated taxa (Phaegopterini, Ctenuchini, Lithosiinae). Abandoned pastures held an impoverished, distinct fauna. Faunal segregation was more pronounced for rare species. Ordination axes reflected primarily the degree of habitat disturbance (openness of vegetation, distance of sites from mature forest) and, to a lesser extent, altitude, but not distance between sampling sites. Main conclusions Despite the geographical proximity of the 21 sites and the pronounced dispersal abilities of adult arctiid moths, local ecological processes were strong enough to allow differentiation between ensembles from mature forest and disturbed sites, even at the level of subfamilies and tribes. Differences in morphology and life‐history characteristics of higher arctiid taxa were reflected in their differential representation (proportions of species and individuals) at the sites, whereas patterns of alpha and beta diversity were concordant. However, concordance was too low to allow for reliable extrapolation, in terms of biodiversity indication, from one tribe or subfamily to the entire family Arctiidae. Phaegopterini (comprising more putative generalist feeders during the larval stages) benefited from habitat disturbance, whereas Ctenuchini (with host‐specialist larvae) were more strongly affiliated with forest habitats.     

蛾类昆虫性信息素通讯系统的遗传与进化

性信息素通讯是普遍而又古老的化学通讯的一种形式。多数鳞翅目蛾类依靠高度种特异性的性信息素通讯寻找配偶以及实现种间生殖隔离。种特异性信息素通讯系统的遗传与进化过程往往是物种形成的组成部分。虽然现在还没有直接证据表明性信息素通讯系统分化可以促使新物种的形成,但是关于性信息素通讯系统的多态性、遗传变异以及遗传机制的研究表明性信息素信号容易发生漂变,而性信息素的接受系统可以适应漂变的性信息素信号。本文对蛾类性信息素通讯系统的遗传与进化的研究进展作了评述,并对性信息素通讯系统进化与物种形成之间的关系进行了讨论。     

Pollinator shifts and the loss of style polymorphism in Narcissus papyraceus (Amaryllidaceae)

Darwin proposed that the driving force for the evolution of style polymorphisms is the promotion of cross‐pollination between style morphs, through accurate placement of pollen on the pollinator’s body. This hypothesis has received much attention, but the effect of different pollinators in the fitness of morphs remains poorly understood. Narcissus papyraceus is a style dimorphic species (long ‐L‐ and short ‐S‐ styled) with isoplethic (1 : 1) and L‐monomorphic populations, mainly visited by long‐tongued (LT) nocturnal and short‐tongued (ST) diurnal pollinators, respectively. We studied natural female fertility of morphs, and assessed the role of diurnal and nocturnal pollinators. We also quantified female fertility of the morphs in experimental populations with different morph ratio, exposed to predominately long‐ or short‐tongued pollinators. We found that with LT pollinators, both morphs were successfully pollinated in all morph ratio conditions, suggesting that these insects could be involved in maintenance of the polymorphism, although other factors may also play a role. However, with ST pollinators, S‐plants displayed less fertility than L‐plants, and mating among L‐plants was favoured, implying that the polymorphism is lost. These results underscore the role of pollinators on variations in style polymorphism.     

The evolution of obligate pollination mutualisms: senita cactus and senita moth

We report a new obligate pollination mutualism involving the senita cactus, Lophocereus schottii (Cactaceae, Pachyceereae), and the senita moth, Upiga virescens (Pyralidae, Glaphyriinae) in the Sonoran Desert and discuss the evolution of specialized pollination mutualisms. L. schottii is a night-blooming, self-incompatible columnar cactus. Beginning at sunset, its flowers are visited by U. virescens females, which collect pollen on specialized abdominal scales, actively deposit pollen on flower stigmas, and oviposit a single egg on a flower petal. Larvae spend 6 days eating ovules before exiting the fruit and pupating in a cactus branch. Hand-pollination and pollinator exclusion experiments at our study site near Bahia Kino, Sonora, Mexico, revealed that fruit set in L. schottii is likely to be resource limited. About 50% of hand-outcrossed and open-pollinated senita flowers abort by day 6 after flower opening. Results of exclusion experiments indicated that senita moths accounted for 75% of open-pollinated fruit set in 1995 with two species of halictid bees accounting for the remaining fruit set. In 1996, flowers usually closed before sunrise, and senita moths accounted for at least 90% of open-pollinated fruit set. The net outcome of the senita/senita moth interaction is mutualistic, with senita larvae destroying about 30% of the seeds resulting from pollination by senita moths. Comparison of the senita system with the yucca/yucca moth mutualism reveals many similarities, including reduced nectar production, active pollination, and limited seed destruction. The independent evolution of many of the same features in the two systems suggests that a common pathway exists for the evolution of these highly specialized pollination mutualisms. Nocturnal flower opening, self-incompatible breeding systems, and resource-limited fruit production appear to be important during this evolution. Received: 19 August 1997 / Accepted: 24 November 1997     

Auditory changes in noctuid moths endemic to a bat-free habitat

If the ears of moths exist primarily to detect the echolocation calls of hunting bats, endemic moths in bat-free areas (i.e., species that have evolved in the absence of the selection pressure maintaining ears) should exhibit signs of deafness. Noctuid moths from the Pacific islands of French Polynesia, a site that has never possessed bats, were sampled and electrophysiologically analysed to test this hypothesis. The auditory sensitivities of seven endemic and twelve immigrant species, captured from the islands of Tahiti, Moorea, and Hiva Oa, were compared. Both classes possess neurally responsive ears, but endemics are significantly deafer than immigrants at frequencies above 35 kHz. This form of deafness is similar to other moths presumably released from the selection pressure of bat predation. I conclude that endemic moths at this site exhibit preliminary stages of deafness and that, considering their small cellular investment, ears in moths will be lost at a slower rate than more complex sensory organs.     

云南菠萝蜜园优势科蛾类的时空生态位分析

【目的】探明菠萝蜜园的蛾类群落组成、优势科时空生态位特征,为害虫的监测预警和生态控制等提供参考依据。【方法】采用灯光诱集的方法收集菠萝蜜园蛾类标本,并进行分类鉴定和统计,利用Levins生态位宽度和Pianka生态位重叠分析主要蛾类的时、空资源占有情况及群落间的竞争共存关系。【结果】共收集到蛾类10科47种,各科物种数占总物种数的比例及其个体数量相对多度均大于5%的优势科为天蛾科(29.79%,48.58%)、灯蛾科(19.15%,24.23%)、毒蛾科(17.02%,9.24%)、螟蛾科(10.64%,5.18%)和尺蛾科(8.51%,7.84%)。优势科的时空生态位宽度普遍较大,生态位重叠主要表现为“宽-宽”型重叠;个体数量相对多度大于1%的7个科两两配对,21对组合中,在时间和空间2个一维生态位上所有组合均具有重叠意义(Q_ij>0.3),在时间和空间维度上分别有8对和7对组合显著重叠(Q_ij>0.6),但在时空二维生态位上具有重叠意义的组合降低到10对,且仅有1对组合显著重叠。【结论】菠萝蜜园蛾类优势科对时空资源占有能力普遍较强,且优势科之间的时空生态位重叠较大,其在时空生态位以外的其他资源维度可能存在较大的分化是其实现共存的原因。     

The role of silk threads as lifelines for caterpillars: pattern and significance of lifeline-climbing behaviour

Abstract.  1. Most lepidopteran larvae use all of their legs (thoracic legs and abdominal prolegs) when walking on solid substrates. When caterpillars involuntarily or intentionally drop from the tree canopy, they can regain their original position by climbing silk lifelines spun out from the head spinnerets. However, the taxonomic distribution of this climbing behaviour in the Lepidoptera is unknown.
2. Here, lifeline-climbing behaviour is reported in 13 lepidopteran species belonging to different taxa (five superfamilies and six families: Zygaenidae, Drepanidae, Geometridae, Lymantriidae, Noctuidae, and Nymphalidae). Caterpillars usually used only the three pairs of thoracic legs to climb lifelines, although they use different methods to walk on solid substrates, according to their taxonomic grouping and number of prolegs.
3. Results suggest that lifeline-climbing behaviour using only the thoracic legs is common among various lepidopteran taxa. The majority of species (12 of 13) climbed lifelines by alternating movement of the left and right set of thoracic legs, aided by side-to-side body movements. Only one of the 13 species, the geometrid Naxa seriaria (Motschulsky), climbed lifelines by drawing them down with its thoracic legs, aided by abdominal looping movements. While side-to-side movement of the abdomen was previously reported in lifeline climbing, this is the first report of the use of looping movements.     

Local and regional climate variables driving spring phenology of tortricid pests: a 36 year study

1. Insect phenology is driven by local climate variables, most notably temperature. Increased warming has been linked to advancements in critical phenophases such as the spring flight of reproductive adults in the mid‐Atlantic region of the U.S.A. 2. Local climate is governed by the fluctuations of large‐scale climate oscillations. In the northern hemisphere, both the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) control the local autumn and winter severity. Low NAO and AO indices are associated with colder autumns and winters, which can delay spring phenology. 3. In this study, 36 years of data from experimental fruit orchards in Biglerville, Pennsylvania, were used to run partial least‐squares regressions in order to determine the climate variables related to the spring phenology of five tortricid pest species. 4. The phenology of the tortricid pests did not advance, even though there was evidence of warming at the research site. 5. Spring temperatures were found to be the most significant climate variables in determining the timing of the spring flights. However, autumn–winter temperatures were also important. 6. For the NAO and the AO, it was found that these oscillations affected the tortricid moths by influencing autumn–winter conditions. The oscillations of the NAO and AO can obscure long‐term changes in phenology. 7. These findings suggest that the inclusion of large‐scale climate oscillations can provide important insights into how climate conditions can influence insect phenology, and presents an opportunity for improving the ability to forecast spring emergence.