亲土苔蛾成虫复眼超微结构

【目的】重叠型眼在昆虫复眼演化中起着重要作用。本研究旨在阐明夜出型亲土苔蛾Manulea affineola复眼类型及结构特征,以期填补灯蛾亚科昆虫复眼研究的空白,扩充夜出型昆虫复眼的特征数据,为探讨重叠型眼的变异趋势及复眼演化提供依据。【方法】运用光学和透射电子显微技术观察亲土苔蛾成虫复眼的超微结构。【结果】亲土苔蛾成虫复眼具有一个透明区,由6个次级色素细胞的透明胞质构成。小眼具8个视网膜细胞,其中1个视网膜细胞较短,仅位于小眼基部。在透明区内,7个视网膜细胞聚集成一束,其远端与晶体束末端相接,但并不形成视杆。在透明区下方,这7个视网膜细胞形成一个中心融合的视杆。在复眼背缘区的小眼的视杆具有近似矩形的横截面,而其余小眼的视杆具多分支状截面。【结论】亲土苔蛾成虫复眼属于重叠型眼;复眼背缘区的矩形视杆很可能与昆虫的偏振敏感性有关。     

Taxonomic review of the genus Lymantria (Lepidoptera: Erebidae: Lymantriinae) in Korea

A taxonomic review of the Korean Lymantria Hübner, 1819 was conducted. A total of nine species of five subgenera with two unrecorded species are listed: Lymantria (Porthetria) dispar Linnaeus 1758, L. (P.) xylina Swinhoe 1903, L. (Lymantria) monacha (Linnaeus 1758), L. (L.) minomonis Matsumura 1933 (new to Korea), L. (L.) similis monachoides Schintlimeister 2004 (new to Korea), L. (L.) lucescens (Butler 1881), L. (Nyctria) mathura Moore 1865, L. (Collentria) fumida Butler 1877, and L. (Spinotria) bantaizana Matsumura 1933. Lymantria (Lymantria) minomonis and L. (L.) similis monachoides are newly added to the Korean fauna. Lymantria (L.) minomonis was found only on Bogildo Island of Jeollanam‐do in the southern part of Korea, and L. (L.) similis monachoides was collected in central Korea. Lymantria (Porthetria) xylina and L. (Collentria) fumida were not examined in this study, and it is considered that the previous records were due to misidentification or they are only distributed in the northern part of the Korean Peninsula. We provide diagnoses of two unrecorded species and adult habitus and genitalia photos of the Korean Lymantria species.     

A new species of Schrankia Hübner, 1825 from China (Lepidoptera,Erebidae, Hypenodinae)

A new species of the genus Schrankia Hübner, 1825, S. pelicano sp. n. is described from Sichuan, China. A diagnostic comparison is made with Schrankia taenialis (Hübner, [1809]) and Schrankia separatalis (Herz, 1904); illustrations of the male holotype and its genitalia are provided. A checklist of the genus with synonyms is given.     

Forest edges enhance mate‐finding in the invasive European gypsy moth,Lymantria dispar

Habitat type, fragmentation, and edge effects can play important roles in the mate‐finding abilities of many species. These effects can be particularly pronounced in low‐density populations, which are often found at the margins of species' ranges or at the leading edge of an invasion. The European gypsy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), is a non‐native insect defoliator in the USA and Canada, where flightless females attract male moths through pheromone production and local extirpation of low‐density populations can be due to mate‐finding failure. To assess the effects of habitat edges on the ability of gypsy moths to find mates, we conducted a release experiment with male gypsy moths using female‐baited trap arrays in fields, at forest edges, and in the forest interior. Reduced mate‐finding was expected in fields and near forest edges based on geographic variation in invasion rates, male flight behavior, and pheromone plume dynamics. However, we found that mate‐finding was highest at forest edges, reduced in fields, and lowest within the forest interior. Within an array, traps closest to the forest edge also had the highest mate‐finding, suggesting that habitat characteristics can influence male flight direction in addition to pheromone cues. These results suggest that a moderate level of forest fragmentation enhances mate‐finding ability in the gypsy moth. Understanding the relationship between habitat heterogeneity and mate‐finding success in invasive species can inform predictions of future spread and assist with management plans that target mating disruption.     

Variation in host plant has no effect on the performance and fitness‐related traits of the specialist herbivore Pareuchaetes insulata

The effect of host plant dissimilarity on insect preference and performance was tested using two morphological forms of Chromolaena odorata (L.) King & Robinson (Asteraceae) (one from Florida, USA, another from South Africa), and a specialist herbivore, Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae: Arctiinae) from Florida, USA, that was introduced as a biological control agent in South Africa. Although this insect did establish at one site, of some 21 sites at which over 800 000 individuals were released, its population level in the field has remained low after an initial outbreak in 2006. To explain the poor performance of P. insulata, we hypothesised that P. insulata larvae prefer Floridian C. odorata to the southern African C. odorata, which is morphologically and probably genetically distinct, and that larvae reared on Floridian C. odorata should have higher fitness and performance. We tested this by comparing insect performance metrics on each of the two plant forms in laboratory experiments. Apart from pupal mass, which was significantly greater on southern African C. odorata, P. insulata performance metrics were similar on both plant forms; there were no significant differences in total leaf area consumed, egg and larval development, immature survival rates, feeding index, host suitability index, growth index, and fecundity between the Floridian and southern African C. odorata plants. In sum, we could not demonstrate that differences in plant forms in C. odorata are responsible for the poor performance of P. insulata in South Africa.     

Difference in nutrient accumulation patterns between diapause-destined and non-diapause-destined larvae of Hyphantria cunea

Nutrient accumulation is crucial in insect diapause preparation because insufficient nutrient accumulation can shorten the diapause period, interfere with diapause development completion, and decrease the probability of surviving the overwintering period. The amounts of lipids and carbohydrates stored in diapausing pupae of Hyphantria cunea (Drury) (Lepidoptera: Erebidae, Arctiinae) are greater than those in the non-diapausing pupae. In this study, we tested the hypothesis that diapause-destined (DD) and non-diapause-destined (NDD) larvae of H. cunea have different nutrient accumulation patterns in penultimate and final instars. The body mass, as well as lipid, carbohydrate, and soluble protein contents, and the efficiency of converting digested food and ingested food into body matter were greater in the DD penultimate and final instars than in the NDD penultimate and final instars. Larger amounts of lipids, carbohydrates, and proteins were absorbed by DD penultimate and final instars and the final instar development period in the DD larvae was prolonged relative to NDD larvae. The activities of fatty acid synthase and glycogen synthase of DD penultimate and final instars were significantly higher than those of NDD larvae. These results suggest that the changes in nutrient accumulation patterns between DD and NDD larvae occur in penultimate and final instars, and that the DD larvae increase their nutrient accumulation during diapause preparation by the combined effect of extending their final-instar development period and improving their digestive efficiency; they increase their lipid and carbohydrate stores by increasing the activities of fatty acid synthase and glycogen synthase in the fat body.     

Temporal relationship between genetic and warning signal variation in the aposematic wood tiger moth (Parasemia plantaginis)

Many plants and animals advertise unpalatability through warning signals in the form of colour and shape. Variation in warning signals within local populations is not expected because they are subject to directional selection. However, mounting evidence of warning signal variation within local populations suggests that other selective forces may be acting. Moreover, different selective pressures may act on the individual components of a warning signal. At present, we have a limited understanding about how multiple selection processes operate simultaneously on warning signal components, and even less about their temporal and spatial dynamics. Here, we examined temporal variation of several wing warning signal components (colour, UV‐reflectance, signal size and pattern) of two co‐occurring colour morphs of the aposematic wood tiger moth (Parasemia plantaginis). Sampling was carried out in four geographical regions over three consecutive years. We also evaluated each morph's temporal genetic structure by analysing mitochondrial sequence data and nuclear microsatellite markers. Our results revealed temporal differences between the morphs for most signal components measured. Moreover, variation occurred differently in the fore‐ and hindwings. We found no differences in the genetic structure between the morphs within years and regions, suggesting single local populations. However, local genetic structure fluctuated temporally. Negative correlations were found between variation produced by neutrally evolving genetic markers and those of the different signal components, indicating a non‐neutral evolution for most warning signal components. Taken together, our results suggest that differential selection on warning signal components and fluctuating population structure can be one explanation for the maintenance of warning signal variation in this aposematic species.