Apolysis without ecdysis in larval development of a strepsipteran, Elenchus tenuicornis (Kirby)

Previous uncertainty concerning the number of larval stages in a strepsipteran ( Elenchus tenuicornis ) was resolved by transmission and scanning electron microscope observations. The first larval instar (triungulinid) is free-living: after entering the host (a delphacid) it undergoes a normal ecdysis. The resulting second instar larva undergoes two further apolyses without ecdysis. In the male, the cuticle of the fourth instar larva tans to form the puparium, while the female becomes sexually mature without a further moult after extrusion of the cephalothorax through the host cuticle. The discarded exuviae of the triungulinid remain in the host abdomen; subsequent larval staging is made possible by the retention of the exuviae ensheathing the larva as each apolysis is accomplished.     

昆虫蜕皮行为的生理生化和分子生物学研究进展

羽化激素与蜕皮触发激素诱发昆虫蜕皮行为及蜕皮末期的其它生理变化。羽化激素在一些特定的脑神经分泌细胞中合成,在蜕皮激素的调控下,释放到中枢神经系统和血淋巴中。蜕皮触发激素是由Inka细胞分泌的,直接作用于中枢神经系统,触发前蜕皮和蜕皮行为。越来越多的证据表明羽化激素可能存在于所有的昆虫中,并作为一种调节蜕皮的一般性激素机制。     

Note on the glide of a bird with wings bent downwards

This note considers the influence of the bending down of the wings of a bird on the performance of its glide. The induced drag of bent wings is compared with the induced drag of a corresponding straight wing. Numerical results are given.     

Condition-dependent ecdysis and immunocompetence in the amphipod crustacean,Gammarus pulex

The exoskeleton of arthropods forms an efficient protection against pathogens, but this first line of defence is periodically weakened during ecdysis, increasing the opportunity for surrounding pathogens to invade the body cavity. Since the richness of pathogens in the environment can be spatially and temporally variable, arthropods may have a fitness advantage in moulting in a place and time of low infection risk. Consistent with this hypothesis, we found that the amphipod crustacean, Gammarus pulex, exhibits temporal adjustment of the moult cycle in response to elevated risks of infection. Interestingly, this phenomenon is variable between two populations and independent of levels of immune defences. These results suggest that plasticity of the moult cycle in response to elevated risks of infection is adaptive and may result from adaptation to local variations in the risk of infection.     

Molecular cloning of three cDNAs encoding putative larval cuticle protein expressed differentially after larval ecdysis from the mulberry longicorn beetle, Apriona germari

Three cDNAs encoding putative larval cuticle protein (LCP) were cloned from the mulberry longicorn beetle, Apriona germari. The three cDNA sequences were 309 bp, 396 bp and 408 bp in length, encoding 103, 132 and 136 amino acid residues, respectively. The predicted molecular masses for these LCPs were approximately 9.2 kDa (AgLCP9.2), 12.3 kDa (AgLCP12.3) and 12.6 kDa (AgLCP12.6). Pairwise identity among AgLCP9.2, AgLCP12.3 and AgLCP12.6 were relatively low. Each AgLCP contained a type-specific consensus sequence identifiable in other insect cuticle proteins. The deduced amino acid sequence of AgLCP9.2 is most similar to Bombyx mori LCP18 and those of AgLCP12.3 and AgLCP12.6 are both most similar to B. mori LCP17. Northern blot analysis revealed that the three AgLCPs showed epidermis-specific expression. The expression profile of AgLCPs after larval ecdysis revealed by Northern blot analysis that the high-level mRNA expression of AgLCPs was detected on the first day of larval ecdysis for AgLCP9.2, on the fifth day for AgLCP12.3 and from the first day of larval ecdysis to the fifth day after larval ecdysis for AgLCP12.6, demonstrating that AgLCP mRNAs are differentially expressed in epidermis after larval ecdysis.     

The New Zealand scorpionfly (Nannochorista philpotti comb.n.): wing morphology and its phylogenetic significance1

The win structure of the New Zealand nannochoristid currently known as Microchorista philgotti: (Tillyard, 1917) is described and discussed. Tubular wing vein sclerotizations are developed in the uper win cuticle only. Shortening of the hindwing CuP-A anastomosis to a single point cannot ge uphed as a nannochoristid autapomorphy. Absence of the Rs₃-Rs₄ crossvein (the diagnostic character for Microchorista) and, perhaps, presence of specialized microtrichia patches on the fore wing are autapomorphic of the New Zealand species. Since the genus Nannochorista, comprising the Australian/Tasmanian and S. American nannochoristids, according to available evidence is paraphyletic in terms of Microchorista the latter is synonymized with the former.     

提高米粒在培养基上发芽率的研究

米粒在培养基上的发芽率与米粒的浸泡时间、消毒时间以及储存时间密切相关,在室温２５℃和１０℃时,浸泡时间分别为２ｈ与４ｈ为佳。消毒适宜时间５ｍｉｎ,米粒随着储存时间越长,发芽率越低。因此,使用当天脱皮的米粒最好。     

中华真地鳖的断足再生

报道了中华真地鳖Eupolyphaga sinensis Walker的断足再生特征。研究结果表明,不同虫龄期的若虫都有断足再生能力;足的不同部位断足后均能再生;断掉不同数量的足后,只要能成活均可再生。断足再生后,继续断掉再生足的原位或其他部位也可以再生。再生足的跗节均比正常的少一节,具有再生不完整性。断足后,只要经1～2次蜕皮,均可再生。断掉一对足的腿节后,再生足出现大小不一的现象,小的一般发育不全,断足数量多容易出现再生足发育不全。再生足比正常足要小,但生长速度要快,断掉足的腿节或跗节后的再生足经过2次蜕皮后基本可恢复到正常足大小。     

The stabilization of locust cuticle

Cuticle from the metathoracic femur of adult locusts (Locusta migratoria) is characterized with respect to changes in water content and in protein extractability during maturation. The swelling behaviour and extractability of fully-sclerotized cuticle are compared to those of chemically-modified, unsclerotized cuticle.It is concluded that although dehydration may contribute to the stabilization of cuticle, it cannot account for the observed differences. The properties of mature cuticle can best be explained by the assumption that covalent cross-links are present between protein molecules.     

The Role of Cuticular Strata Nomenclature in the Systematics of Nemata

A system of cuticular nomenclature based on the strata observed in Enoplia is proposed. Nematode cuticle is divided into four fundamental strata: epicuticle, exocuticle, mesocuticle, and endocuticle. Application of this system allows the correlation of complementary strata throughout Nemata. The major taxonomic categories within Nemata are differentiated on the basis of their cuticular strata as compared with the Enoplia model cuticle.     

Effects of methoprene and juvenile hormone on larval ecdysis,emergence, and metamorphosis of the endoparasitic wasp, Apanteles congregatus

Topical application of juvenile hormone I and III or the hormone analogue methoprene to parasitized Manduca sexta larvae inhibited subsequent emergence of the endoparasitic wasp Apanteles congregatus. Methoprene treatment inhibited wasp emergence in a dose-dependent manner, causing either a delay or total inhibition of emergence. These results were interpreted as reflecting inhibitory effects of juvenile hormone on the second-larval ecdysis of the parasitoid that normally occurs during emergence from the host larva. Parasitoid ecdysis was disrupted even when methoprene was applied to host larvae a few hours prior to the normal expected time of emergence. A correlation between the number of emerging parasitoids and the timing of emergence was seen in methoprene-treated hosts, and few parasitoids emerged after day 9 of the host's fifth-instar. Our findings suggest that the suppression of emergence by juvenile hormone analogues noted in previous studies may be due to a similar inhibitory effect on parasitoid ecdysis. We also observed that parasitoids emerging from hosts treated with a low dose of methoprene (1 μg) later pupated normally but then formed nonviable pupal-adult intermediates. Thus use of this insect growth regulator must be undertaken carefully to prevent possible adverse effects on natural parasitoid populations.     

Effects of ingested phytoecdysteroids on the growth and development of two Lepidopterous larvae

The effects of ingested or injected 20-hydroxyecdysone on silkworm larvae (Bombyx mori) including death without moulting, death following completion of promoted moulting, death during promoted moulting (ecdysis inhibition) and inhibition in growth with and without effects on moulting, are dependent upon the concentration of exogenous hormone, the precise developmental stage of the treated larvae, and the duration of exposure to the exogenous ecdysteroid. Comparisons of 20-hydroxyecdysone with other phytoecdysteroids in the silkworm and pink bollworm, Pectinophora gossypiella, show a similar but more potent effect induced by ponasterone A, while cyasterone causes an ‘antiecdysone’ effect.