Adult eclosion rhythm of the Indian meal moth Plodia interpunctella: response to various thermocycles with different means and amplitudes

In addition to photoperiod, thermoperiod (or thermocycle) might be an important Zeitgeber for entraining the circadian oscillator controlling adult eclosion rhythm in the Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae). This is confirmed by exposing larvae receiving diapause‐preventing treatments to various thermocycles with different means and amplitudes of temperature. The thermocycles investigated in the present study are TC 8 : 16 h, TC 12 : 12 h, TC 16 : 8 h and TC 20 : 4 h, where T and C represent thermophase (30 °C) and cryophase (20 °C), respectively. For all thermocycles, the peak of adult eclosion rhythm occurs at around the mid‐thermophase. This indicates that the larvae use both ‘temperature‐rise’ and ‘temperature‐fall’ signals to adjust the eclosion phase in each thermocycle. The absence (DD) or presence (LL) of light affects this time‐keeping system slightly under the given thermocycle. The rhythmic adult eclosion noted after exposure of larvae to 30 °C DD for 14 days is recorded in the thermocycles (TC 12 : 12 h, DD; mean temperature = 25 °C) with different amplitudes of 27.5/22.5 °C, 26.5/23.5 °C and 25.5/24.5 °C. The peak in adult eclosion advances in time as the amplitude of the temperature cycle decreases. In the temperature cycle of 25.5/24.5 °C, a peak occurs at the end of the cryophase, 2 h before the temperature‐rise. The adult eclosion rhythm is also observed under various thermocycles (TC 12 : 12 h, DD) consisting of different temperature levels (30 to 20 °C) with different amplitudes. It is found that the temporal position of the peak advances significantly when the amplitude of the thermocycle becomes lower.     

Cellulose and Xylan Utilisation in the Lower Termite Reticulitermes speratus

The distribution of the enzymes of cellulose and xylan metabolism namely endo-beta-1,4-glucanase, beta-glucosidase, endo-beta-1,4-xylanase and beta-xylosidase activities, in Reticulitermes speratus (Kolbe) was measured both in the salivary glands and in the major gut sections and along the length of the gut in freshly collected termites. The majority of the endo-beta-1,4-glucanase activity (77.8%) was found in the salivary glands which also contained 23.9% of the beta-glucosidase activity. At least 70% of the remaining activity was located in the anterior section of the hindgut. A small amount of endo-beta-1,4-xylanase activity (2.4%), but no beta-xylosidase activity, was present in the salivary glands. The majority of these activities were in the anterior section of the hindgut. The RQ of freshly collected termites at 25 degrees C was 1.03+/-0.01. Maintaining termites for 16 days on wood, cellulose and xylan showed that the RQ values of termites fed on wood or xylan were not significantly different from those of freshly collected termites but significantly increased when maintained on cellulose. The RQ of starved termites after 11 days was 0.81+/-0.02. There were three effects on protozoan populations of feeding termites xylan for 20 days. One species, Dinenympha parva was not affected, while five others, Pyrsonympha grandis, Holomastigotes elongatum, Dinenympha rugosa, Dinenympha leidy and Dinenympha porteri survived for 20 days but slowly decreased in numbers. The numbers of P. grandis and D. leidy surviving for 20 days were significantly different from those in starved termites. The third group comprising the two large species, Teratonympha mirabilis and Trichonympha agilis and three small species, Pyrsonympha modesta, Dinenympha exilis and Dinenympha nobilis disappeared within 15 days as in starved termites. It is suggested that protozoa in the first two groups are xylanolytic. Protozoan populations on wood and cellulose diets were not markedly affected. Selective removal of the protozoa by u.v. irradiation led to the loss of xylanolytic activity and a life span comparable to starved termites. Copyright 1997 Elsevier Science Ltd. All rights reserved     

Action Spectrum for Photoactivation of the Water-splitting System in Plastids of Intermittently Illuminated Wheat Leaves

The chloroplasts from wheat leaves developed under intermittent illumination (1 ms light + 12 min dark) were able to photoreduce DPIP with DPC as electron donor but unable to photoreduce DPIP with water as electron donor. On exposure of these leaves to continuous light, the Hill activity with water as electron donor was rapidly induced. The photoactivation was sensitive to the treatment with DCMU prior to exposure to continuous light. The action spectrum for the photoactivation showed a sharp band at 680 nm with a distinct shoulder at 650 nm, and was similar to the absorption spectrum of photosytem-2 particles. These data suggest that the electron transfer driven by photosystem 2 is essential for the activation of the water-splitting system in the chloroplasts of intermittently illuminated leaves.     

Spatiotemporal distribution and resource use of scoliid wasps (Hymenoptera) in coastal sand dunes

The spatial and temporal distributions of scoliid wasps in the coastal sand dunes at Hakoishi, Kyoto Prefecture, Japan, were investigated using three different sampling methods in 2002 and 2003. Of eight scoliid species collected in the present study, five species, Scolia historionica, Campsomeriella annulata, Scolia decorata, Scolia oculata, and Megacampsomeris schulthessi, were dominant. The flying insects caught by Malaise traps and flower‐visiting insects caught by insect nets were mostly males, and this biased pattern was due to the active mate‐searching behavior of male wasps and their frequent visits to flowers to supplement energy consumed by such behavior. Given that the ground traps caught females exclusively, female wasps seemed to actively engage in host‐searching behavior on and below the ground. Of the wasps caught by Malaise traps and flower‐visit sampling, five dominant species showed spatially different habitat use: S. historionica and C. annulata mainly occupied the grassland zone on the plain (Gp), S. decorata occupied the grassland zone on the terrace (Gt) and the forest zone (Fp), S. oculata occupied the small scrub zone on the plain (Sp), and M. schulthessi occupied the small scrub zone on the terrace (St). Ground trap samples also indicated that S. historionica and C. annulata shared habitats. On the basis of the observed seasonal changes in wasp abundance and the degree of wing wear as an index of wasp age, S. historionica and C. annulata are thought to be bivoltine species, whereas S. decorata, S. oculata, and M. schulthessi are thought to be univoltine species. These scoliid wasp species may play an important role in pollinating coastal plants in the grassland zone.