光周期和温度对亚洲玉米螟滞育诱导的影响

亚洲玉米螟Ostrinia furnacalis (Guenée)属兼性滞育昆虫, 其滞育特性与种群利用适生境的最大化和季节性活动密切相关。解析季节性因素如光周期和温度对其滞育的诱导作用可为预测种群发生动态提供科学依据。本实验在HPS 500型和HPG-320H型自动控制环境气候箱中, 测定了RH 80%下温度20℃, 27℃和30℃与11个光周期组合对吉林农安（NA）、 河北衡水（HS）、 广东惠州（HZ）和海南海口（HK）等4个地理种群的滞育诱导作用。结果表明： 光周期、 温度及其交互作用均对亚洲玉米螟滞育诱导具有重要影响, 其中光周期在滞育诱导中起主导作用。在20℃条件下, 其光周期反应曲线属典型的长日照反应型, 临界光周期随种群分布的地理纬度降低而缩短, 4个地理种群NA, HS, HZ和HK的临界日昼长依次为14 h 3 min, 13 h 59 min, 13 h 32 min和13 h 7 min, 最有效的滞育诱导光周期是日昼长12 h。另一方面, 随种群分布纬度升高, 其对光周期诱导滞育的敏感性降低。温度为27℃时, 其光周期反应曲线为短日照 长日照反应型, 各种群有两个临界光周期, 临界日昼长依次为12 h 50 min和13 h 32 min, 11 h 35 min和13 h 8 min, 12 h 58 min和13 h 1 min, 以及11 h 50 min和12 h 26 min, 且最有效的滞育诱导光周期范围的滞育率明显低于20℃。一定温度范围内（20℃～27℃）, 随温度升高, 临界光周期缩短; 温度达到30℃时则滞育显著被抑制, 滞育率仅为4.3%或更低。这些结果说明温度对亚洲玉米螟滞育的光周期诱导具有很强的补偿作用。因此, 在自然界亚洲玉米螟的滞育属具有温度补偿作用的长日照反应型昆虫, 临界光周期随地理纬度北移而增长; 种群滞育的短日照 长日照反应型特性可能是产生局部世代种群的重要内因。     

Sensitivity to juvenile hormone is not reduced in clustering monarch butterflies, Danaus plexippus, in Australia

ABSTRACT. Female monarch butterflies, Danaus plexippus (L.) were collected from clusters in the Sydney region at weekly intervals after cluster formation. They were neck-ligated and injected with juvenile hormone (JH) in order to test for any period of lowered JH sensitivity during the non-reproductive clustering phase. Response was assessed by production of mature oocytes. In all weekly samples, the mean response was equal to or greater than that of newly emerged females reared and maintained in optimal conditions, and was substantially higher than that reported for diapausing monarchs in North American clusters. The result is further evidence for the absence of a true reproductive diapause in New South Wales populations.     

Phenology of weight, moisture and energy reserves of Australian monarch butterflies, Danaus plexippus

Abstract. 1. In the Sydney area of New South Wales, dry weights of reproductive monarch butterflies averaged 156 mg and were higher during winter than in other seasons. Dry weights of non-reproductive monarchs ranged from 216 to 324 mg and declined by 15–25% during over wintering.
2. Fat in reproductive butterflies ranged from 0.009 to 0.017g/0.1g dry weight and was lower during winter than in other seasons. Fat content of non-reproductive monarchs was higher (0.019–0.037 g/0.1g) and declined by 24–51% during over wintering.
3. Lean dry weights of reproductive monarchs were lower than those of non-reproductive individuals. Lean dry weights of non-reproductive butterflies increased rapidly at the beginning of over wintering and remained high throughout the winter. Analysis of protein content indicated the higher lean weight of non-reproductive monarchs was due to greater protein levels.
4. Moisture content of monarchs did not vary with season or reproductive status and appeared to be correlated with ambient humidity.
5. Non-reproductive monarch butterflies in New South Wales adjust bio chemically during over wintering. Energy reserve dynamics of these butterflies are comparable to those that occur in non-reproductive monarchs in North America.     

Contact chemoreception related to host selection and oviposition behaviour in the monarch butterfly, Danaus plexippus

Abstract. Behavioural events during host selection by ovipositing monarch butterflies (Danaus plexippus (L.), Danainae, Nymphalidae) include tapping the leaf surface with fore-tarsi and touching this surface with mid-tarsi (‘drumming’) and antennae. Flavonoids identified from host plant extracts are known to stimulate oviposition. Scanning electron microscopy revealed the presence of contact-chemoreceptor sensilla on all appendages that contact the leaf surface. This electrophysiological study was conducted to identify the contact chemoreceptors that are sensitive to the known oviposition stimuli and are therefore probably involved in host recognition. Receptor cells of conspicuous sensilla grouped in clusters on fore-tarsi of females were sensitive to the behaviourally active butanol fraction of host plant (Asclepias curassavica) extract. However, these receptors generally had low sensitivity to three oviposition-stimulating flavonoids identified from this fraction, but they were also sensitive to the butanol fraction of a non-host (Brassica oleracea). Chemoreceptors in sensilla of the tarsomers 2–4 of the mid-legs also responded to the behaviourally active fraction of host plant extract and showed some sensitivity to two of the flavonoids that stimulate oviposition. Similar results were obtained from receptor cells in sensilla on the tip of the antennae. Most of these sensilla had cells responding to the butanol fraction of A. curassavica extract but only 25% of them were also sensitive to one of the behaviourally active flavonoids. These electrophysiological results, in combination with behavioural observations, suggest that host selection in monarch butterflies relies on a complex pattern of peripheral sensory information from several types of tarsal and antennal contact chemoreceptors.     

温度和光周期对绿盲蝽滞育诱导的影响

为了阐明环境因子对绿盲蝽Apolygus lucorum Meyer-Dür卵滞育诱导作用,测定了3个温度和6个光周期组合处理对绿肓蝽的滞育诱导和绿盲蝽光周期感应的敏感虫态,系统调查了绿肓蝽在不同温度和不同光照组合下所产卵的孵化率.结果表明:绿盲蝽的敏感虫态为1龄若虫;在17℃,20℃和23℃3个不同温度下,光照时间小...     

Host plant mediation of diapause induction in the cabbage beetle, Colaphellus bowringi Baly （Coleoptera： Chrysomelidae）

The cabbage beetle, Colaphellus bowringiBaly （Coleoptera： Chrysomelidae）, is a serious pest of crucifers in China, undergoing an imaginal summer and winter diapause in the soil. The effects of host plants on diapause incidence were tested in the beetle. The ratio of adults entering diapause was significantly low when they fed on the mature leaves of Chinese cabbage Shanghaiqin （Brassica chinesis var communis） than those feeding on Chinese cabbage Suzhouqin （Brassica chinesis var communis）, radish （Raphanus sativus var longipinnatus） and stem mustard （Brassicajuncea vat tumida） at 25℃ combined with 13：11 （L： D） h. Fewer adults entered diapause on young leaves compared to physiologically aged and mature radish leaves at 25℃ combined with 13：11 （L： D） h. The effect of host plant species on diapause induction was also evident under continuously dark rearing conditions or at different photoperiods. These experimental results demonstrate that host plant mediation of diapause induction exists in the cabbage beetle. However, at temperatures ≤20℃ or photoperiods of 16：8 （L： D） h combined with 25℃, all individuals entered diapause regardless of the host plants, indicating that the effects of host plants on diapause induction could be expressed only within a limited range of temperatures and photoperiods.     

温度和光周期对管侧沟茧蜂滞育诱导及滞育茧的低温冷藏

【目的】为明确诱导管侧沟茧蜂Microplitis tuberculifer 滞育的主要因子,在田间和室内研究了不同温度和光周期下管侧沟茧蜂的滞育率和滞育茧的最佳冷藏温度。【方法】田间实验分别从8月31日到9月25日每隔5 d在室外罩笼内释放管侧沟茧蜂寄生的粘虫幼虫,待寄生蜂结茧后统计子代蜂的滞育率。室内实验共设5个不同温度（16℃, 18℃, 20℃, 22℃和24℃）和7个不同光周期（6L:18D, 8L:16D, 10L:14D, 12L:12D, 14L:10D, 16L:8D和18L:6D）,分别统计寄生蜂在各个处理条件下的滞育率。【结果】在河北中部地区秋季自然条件下,8月底当日平均气温为24.4℃,日平均光照时间为12 h 51 min 时,少数蛹（5.08%）开始进入滞育;9月25日,当日平均气温为17.2℃,日平均光照时间为11 h 36 min以下时,几乎所有蛹个体进入滞育,滞育率达到99.70%。在室内人工控制条件下,当温度为22℃以上,无论光周期如何变化,管侧沟茧蜂不能进入滞育,所结茧全部为非滞育茧。温度为22℃以下存在光周期反应,在温度16℃, 18℃和20℃,光周期10L:14D时形成滞育茧数量最多,滞育率分别为100%, 89.75% 和 29.58%。可见温度和光周期二者共同影响管侧沟茧蜂的滞育。滞育茧在0℃左右条件下冷藏 240 d 和5℃左右环境条件下冷藏180 d, 成虫的羽化率和寄生能力与发育茧差异不显著(P>0.05);0℃条件下冷藏300 d,滞育茧仍有79%可以正常羽化。【结论】该寄生蜂在秋季进入滞育主要是低温条件和短光照反应相互作用的结果,滞育茧在0℃和5℃温度下至少可以保存240 d。这些结果对管侧沟茧蜂的大规模繁殖和滞育茧的保存具有重要参考价值。     

Oviposition preference and larval performance of monarch butterflies (Danaus plexippus) on two invasive swallow-wort species

The potential of two invasive herbaceous vines Vincetoxicum nigrum (L.) Moench and Vincetoxicum rossicum (Kleopow) Barbar. (Asclepiadaceae) to reduce monarch butterfly (Danaus plexippus L.) (Lepidoptera: Nymphalidae, Danainae) populations was investigated by evaluating oviposition selection in adult monarch butterflies and larval feeding preference in choice tests comparing the native host plant of monarch butterflies, Asclepias syriaca L. (Asclepiadaceae) and the two non‐indigenous Vincetoxicum species. In both choice and no‐choice tests, no eggs were oviposited on either of the two Vincetoxicum species whereas over 66 eggs per female were oviposited on A. syriaca plants. All first instar larvae allowed to feed on A. syriaca for 48 h survived while a significantly lower proportion survived on V. rossicum (44%) and V. nigrum (14%). Mean weight of larvae that did survive on the Vincetoxicum species was significantly lower than the mean weight of larvae that fed on A. syriaca. The mean weight of surviving larvae, however, did not differ between the two Vincetoxicum species. The mean proportion of leaves consumed by larvae feeding on A. syriaca was significantly greater than the mean proportion of leaves consumed by larvae feeding on either Vincetoxicum species. Findings from this research indicate that V. rossicum and V. nigrum are not viable hosts of monarch butterflies and are likely to pose little direct threat to their populations as oviposition sinks. The ability of these highly aggressive plants, however, to out‐compete and displace the native host of monarchs, A. syriaca, may pose a more serious threat. The potential of monarch populations to adapt to the two Vincetoxicum species as host plants over the long‐term is discussed.     

Effects of photoperiod and temperature on pupal diapause induction of grape berry moth Lobesia botrana

Abstract. The grape berry moth, Lobesia botrana Denn. & Sciff. (Lepidoptera: Tortricidae), one of the most injurious pest of grape berries in Greece, is a multivoltine species that overwinters as diapausing pupae. The effects of several diel and non-diel photoperiods and of temperature, experienced by eggs and larvae, on pupal diapause induction were investigated. The diapause response curve was of Type I (long day type) and the determining factor was the duration of scotophase (> 11 h), regardless of the duration of photophase. However, at very short (< 4 h) photoperiods, the incidence of diapause was also high. Diapause was positively and significantly correlated with the egg-larval developmental time, pupal mortality and the duration of the pupal stage. Eggs and larvae reared under LD 12 : 12 h photoperiod and various temperatures (from 12 to 30 °C) produced diapausing pupae (almost 100%), but the duration of the pupal stage (intensity of diapause) increased with increasing temperature. Under continuous darkness, however, the percentage diapause decreased with increasing temperature. Single and double 1-h light pulses were applied systematically at various times during the scotophase of six diapause-inducing diel photoperiods. Two photosensitive points in time (called A and B) were revealed, during which illumination resulted in a significant decrease of diapause induction. The decrease was much greater during the first sensitive period (early in scotophase) rather than in the second (late in the scotophase).     

Effects of photoperiod and temperature on reproductive diapause in Ophraella communa (Coleoptera: Chrysomelidae), a potential biocontrol agent against Ambrosia artemisiifolia

Abstract To investigate the seasonal adaptation strategies of Ophraella communa to new habitats, the effects and regulation mechanisms of photoperiod and temperature on the reproductive diapause in a population collected from Changsha, Hunan were examined. Adults showed obvious reproductive diapause, which was regulated by photoperiod and temperature. At 30°C, there was no adult diapause occurring under either long‐day or short‐day conditions; at 25°C the pre‐oviposition period was short and fecundity was high in adult females under L : D 16 : 8 h, whereas under L : D 12 : 12 h, a few females entered reproductive diapause; at 20°C under short‐day conditions, all female adults entered diapause. The pre‐oviposition period was significantly prolonged when the pupae and adults were transferred from long‐days to short‐days, but the day length influence was not obvious when they were transferred only in the adult stage. However, the fecundity dropped greatly no matter whether the photoperiod shifted to short‐days only in the adult stage or whether the shift occurred in both the pupal and adult stage. The fecundity was extremely low when photoperiod shifted from long‐days to short‐days in both pupal and adult stages. This was an indication that the pupal and adult stages were the photoperiod‐sensitive stage for adult reproductive diapause. This was especially true for the photoperiod in the pupal stage, which has a distinctly significant regulative effect on reproductive diapause. Additionally, this article also addresses the reason for different photoperiodic response patterns in reproductive diapause induction between the Changsha strain and the Tsukuba strain (Japan) of O. communa.     

Effects of soil nutrients on the sequestration of plant defence chemicals by the specialist insect herbivore,Danaus plexippus

1. Although anthropogenic nitrogen (N) enrichment has significantly changed the growth, survival and reproduction of herbivorous insects, its effects on the defensive sequestration of secondary chemicals by insect herbivores are less well understood. Previous studies have shown that soil nutrient availability can affect sequestration directly through changing concentrations of plant defence chemicals, or indirectly through altering growth rates of herbivores. There has been less exploration of how nutrient deposition affects the consumption of secondary chemicals and subsequent sequestration efficiency. In the current study, the overall effect of soil N availability on cardenolide sequestration by the monarch caterpillar Danaus plexippus was examined. Specifically, the effects of soil nutrient availability on growth, consumption, excretion and sequestration efficiency of cardenolides by D. plexippus larvae fed on the tropical milkweed Asclepias curassavica were measured. 2. The results showed that soil N and phosphorus (P) fertilisation significantly reduced caterpillar growth rate and the sequestration efficiency of cardenolides by monarch caterpillars feeding on A. curassavica. The lowered sequestration efficiency was accompanied by higher concentrations of cardenolides in frass. Although the total cardenolide contents of caterpillars were lower under high N or P fertilisation levels, caterpillar cardenolide concentrations were constant across fertilisation treatments because of lower growth rates (and therefore lower body mass) under high fertilisation. It is concluded that anthropogenic N deposition may have multiple effects on insect herbivores, including their ability to defend themselves from predators with sequestered plant defences.     

Effects of photoperiod and temperature on the development and diapause of the bark beetle Ips typographus

Abstract:  Diapause was induced in a Central European population of Ips typographus grown at 20°C when the day length decreased below 16 h [50% diapause incidence occurred in the 14.7:9.3 h L:D (light:dark) regime]. The non-diapausing adults fed on days 2–6 and 10–14 after the ecdysis and swarmed after the second feeding bout with chorionated eggs in the ovaries and sperm in the spermiducts. Neither gonads nor the flight muscles matured and no swarming occurred in the diapausing adults. The development from egg to adult took about 34 days in both 18:6 h (no diapause) and 12:12 h L:D (diapause) regimes, but it was extended by up to 30% without diapause induction when only larvae or pupae were exposed to L:D 12:12 h. Diapause was induced in insects reared at L:D 12:12 h through the last larval and the pupal instars and/or in the adult stage. Temperature ≥ 23°C prevented diapause induction at L:D 12:12 h but diapause occurred at L:D 14:10 h associated with 26:6°C thermoperiod. The effect of thermoperiods on the developmental rate requires further research. Exposure of the non-diapausing adults to 5°C for several days blocked feeding and evoked a diapause-like state, whereas diapausing adults fed and their gonads slowly developed at this temperature. Diapausing adults exposed in forest to low night temperatures and transferred in October to 20°C readily reproduced at 18:6, but not 12:12 h L:D photoperiods. After 2-months at 5°C and darkness, they became insensitive to the photoperiod, matured and most of them also swarmed at 20°C in the 12:12 h L:D regime. In a Scandinavian population, diapause occurred at 18:6 h L:D and was terminated either by exposure to 5°C or by very long photoperiod (L:D 20:4 h) combined with high temperature (23°C).     

Effects of photoperiod and temperature on diapause induction in Conogethes punctiferalis (Lepidoptera: Pyralidae)

The yellow peach moth, Conogethes punctiferalis (Guenée), a multivoltine species that overwinters as diapausing larvae, is one of the most serious insect pests on maize in China. Effect of photoperiod and temperature on larval diapause was examined under empirical laboratory conditions. Short‐day treatments caused larval diapause at 25°C, and the critical photoperiod was between 12 and 13 h (or 12 h 51 min) light per day. No sensitive instar was identified for diapause induction under alternated short‐ (L : D 11 : 13 h) and long‐day (L : D 14 : 10 h) treatments at different larval stages. However, accumulative treatment of three instars and 10 d under short‐day treatment was required for the induction of 50% larval diapause. All larvae entered diapause at 20°C, whereas less than 3% did so at 30°C, irrespective of the long‐ or short‐day treatment. Furthermore, under the short‐day treatment, more than 90% of larvae went into diapause with temperatures ≤ 25°C, but less than 17% did so at 28°C. In contrast, under the long‐day treatment, less than 19% of larvae went into diapause with temperatures ≥ 23°C. The forward shift (5°C) of critical temperature under the long‐day regime demonstrated the compensatory effect of temperature and photoperiod on diapause induction. In conclusion, C. punctiferalis had a temperature‐dependent type I photoperiodic diapause response; there was no sensitive instar for diapause determination, but the photoperiodic accumulation time countermeasures both of the short‐day cycles and the number of instars exposed, and the photoperiodic diapause response, was a temperature‐compensated phenomenon.     

Effects of photoperiod and temperature on diapause induction and termination in the swallowtail,Sericinus montelus

Abstract Sericinus montelus overwinters as diapausing pupae. In the present study, the effects of photoperiod and temperature on diapause induction and termination of diapause are investigated. The results obtained demonstrate that high temperature can reverse the effect of short day‐lengths on diapause induction. Under an LD 12 : 12 h photoperiod, all pupae enter diapause at 15, 20 and 25 °C, whereas all pupae develop without diapause at 35 °C. No pupae enter diapause under an LD 14 : 10 h photoperiod when the temperature is above 20 °C. Photoperiodic response curves obtained at 25 and 30 °C indicate that S. montelus is a long‐day species and the critical day‐length is approximately 13 h at 25 °C. At 25 °C, the duration of diapause is shortest when the diapausing pupae are maintained under an LD 16 : 8 h photoperiod and increases under LD 14 : 10 h and LD 12 : 12 h photoperiods. Under an LD 16 : 8 h photoperiod, the duration of diapause is shortest when the diapausing pupae are maintained at 25 °C, followed by 20 and 30 °C, and then at 15 °C. These results suggest that a moderate temperature favours diapause development under a diapause‐averting photoperiod in this species. The duration of diapause induced by an LD 12 : 12 h photoperiod is significantly longer at 25 °C than those at 15, 20 and 30 °C, and is shortest at 15 °C. At 25 °C, the duration of diapause induced by LD 6 : 18, LD 12 : 12 and LD 13 : 11 h photoperiods is similar and longer than 90 days. Thus, the diapause‐inducing conditions may affect diapause intensity and a photoperiod close to the critical day‐length has significant influence on diapause intensity in S. montelus.     

Cardiac glycosides and oviposition by Danaus plexippus on Asclepias fruticosa in south-east Queensland (Australia), with notes on the effect of plant nitrogen content

Abstract. 1. Previous studies which attempt to relate oviposition by female monarchs, Danaus plexippus (L.), to the cardiac glycosides of their milkweed host plants are reviewed and found to be defective.
2. Here we followed ovipositing females in the field and recorded their oviposition behaviour on individual Asclepias fruticosa (L.) plants. The cardenolide glycoside and per cent nitrogen of each of these plants and also of a control set of plants was recorded.
3. Milkweeds accepted by females, on which egg laying took place, had significantly lower mean cardenolide levels compared with rejected plants and a control sets of plants.
4. Most oviposition ( c. 70%) took place on plants with intermediate cardenolide (CG) levels (=200–300 μg/0.1 g DW).
5. The mean CG level in A.fruticosa was 345 μg/0.1 g DW (SD = 138, n =122, range 119–719).
6. There was no relationship between monarch oviposition behaviour and plant per cent nitrogen.     

The integrative effects of population density, photoperiod, temperature, and host plant on the induction of alate aphids in Schizaphis graminum

The wheat aphid Schizaphis graminum (Rondani) displays wing dimorphism with both winged and wingless adult morphs. The winged morph is an adaptive microevolutionary response to undesirable environmental conditions, including undesirable population density, photoperiod, temperature, and host plant. Here we studied the integrative effects of population density, photoperiod, temperature, and host plant on the induction of alate aphids in S. graminum. The present results show that these four factors all play roles in inducing alate aphids in S. graminum but population density is the most important under almost all circumstances. In importance, population density is followed by photoperiod, host plant, and temperature, in that order. These results indicate that ambient environmental factors are highly important to stimulation of alate aphids in S. graminum, especially when population density reaches 64 individuals per leaf.     

Effect of photoperiod and temperature on reproduction of the monarch butterfly,Danaus plexippus

Optimal posteclosion ovarian development in monarch butterflies occurs at about 28°C. Higher and lower temperatures appear progressively inhibitory. Reproductive gland development in males follows a similar pattern. Juvenile hormone injections stimulate oöcyte maturation in animals held at 20 and 35°C but are most effective at the higher temperature. Juvenile hormone injections are ineffective at 10 and 15°C. The stimulatory effect of increasing photophase on ovarian development was most apparent at optimal temperature. The possible significance of our findings to monarch migration is discussed.     

Interactive effects of photoperiod and temperature on diapause induction and termination in the yellow-spotted longicorn beetle, Psacothea hilaris

Abstract. The interactive effects of temperature (20 °C or 25 °C) and photoperiod (LD 12 : 12 h or LD 15 : 9 h) on diapause induction and termination are investigated in the west‐Japan type yellow‐spotted longicorn beetle, Psacothea hilaris (Pascoe) (Coleoptera: Cerambycidae). Larval diapause of P. hilaris is induced under three diapause‐inducing conditions (20 °C–SD, 20 °C–LD and 25 °C–SD), and the diapause larvae are transferred to one of four conditions (20 °C–SD, 20 °C–LD, 25 °C–SD or 25 °C–LD) for observation of pupation, which indicates termination of diapause. The intensity of diapause induced under the three conditions increases in the order 20 °C–SD < 25 °C–SD < 20 °C–LD, when assessed by the time course of pupation after the transfer. On the other hand, the effectiveness of the temperature–photoperiod combinations to terminate diapause is in the order 25 °C–SD (ineffective) < < 20 °C–LD < 25 °C–LD < 20 °C–SD. Among the temperatures (5, 10, 15 and 20 °C) examined, 15 °C is the most effective in terminating diapause under the short day; diapause in most larvae appears to have been completed in 15 days.     

Influence of thermoperiod and photoperiod on reproductive diapause in Bruchidius atrolineatus (Pic) (Coleoptera, Bruchidae)

Abstract Bruchidius atrolineatus (Pic) is a common pest infesting cowpea seeds ( Vigna unguiculata Walp) in Africa. In the Sahelian zone, the adults are in reproductive diapause during the dry season. Diapause induction depends on the climatic conditions during embryonic and post-embryonic development. A strain of B. atrolineatus originating from the Niamey (13^oN) was reared in different thermoperiodic and photoperiodic conditions. In the thermoperiodic regime 40:25^oC, in continuous darkness, induction of diapause was dependent on the duration of the thermophase. Photoperiod could also influence diapause induction but the response depended on the temperature. When the beetles were reared in conditions of LD 12:12 h, 40:25^oC, for seven generations, the proportion of diapausing adults decreased and their sensitivity to photoperiod increased. In LD 14:10 h, 40:25^CC, the proportion of diapausing adults remained high regardless of the photoperiod. In these conditions, the first emerging adults were sexually active and were used for selection of a strain with a low incidence of diapause. After twelve generations, the proportion of diapausing beetles was lower than 5%. The responses of this selected strain to photo- and thermoperiods were reduced. The sensitivity of B. atrolineatus to photoperiod and thermoperiod could be controlled by genetic systems as observed in other insect species.     

光周期和温度对草地螟滞育诱导的影响

草地螟Loxostege sticticalis以老熟幼虫滞育越冬。在室内通过人工诱导的方法对其滞育的光周期和温度诱导条件进行了研究。结果表明:草地螟是一种典型的长日照发育型种类。光周期、温度及其交互作用均对草地螟滞育诱导具有重要影响, 其中光周期起主导作用, 温度伴随着光周期起作用。对幼虫滞育诱导最有效的光周期是L12∶D12; 随着温度的升高, 临界光周期呈缩短趋势（18℃除外）。18, 22, 26和30℃条件下幼虫滞育的临界日长依次为13.97, 14.48, 13.92 和12.88 h。光敏感实验揭示:21℃时草地螟对光照反应最敏感时期为幼虫孵化后的11～17 d（约5龄幼虫）, 但孵化后7～11 d（约4龄幼虫）的短光照积累对提高滞育率也有重要作用, 可以将滞育率从40.0%提高到90.0%。