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1.
Serangium parcesetosum Sicard (Col., Coccinellidae) is considered one of the important predators of whiteflies. However, knowledge about its preferences for different prey stages, species and parasitized prey is still lacking in the literature. The present work investigated the preferences of S. parcesetosum for different stages of B. tabaci, different prey species and B. tabaci parasitized by Encarsia formosa Gahan (Hym., Aphelinidae) by prey consumption at different temperatures in the laboratory. Results showed that L2 and L4 predatory instars of S. parcesetosum preferred puparia to nymphs and eggs of Bemisia tabaci (Genn.) (Hom., Aleyrodidae). The mean daily prey consumption was 5.1–9.0, 4.5–6.2 and 3.6–4.3 by L2 and 6.4–9.7, 5.5–8.5 and 2.5–7.5 by L4 for puparia, nymphs and eggs, respectively. Adult females, however, indicated a significantly greater preference for both puparia and nymphs, consuming a daily mean of 6.4–7.5 puparia and 5.1–6.7 nymphs, but only 3.0–4.7 eggs. At 18 and 30 °C, all S. parcesetosum stages tested significantly preferred B. tabaci and Trialeurodes vaporariorum Westwood (Hom., Aleyrodidae) over the other three prey species offered. At both temperatures, all predatory stages preferred B. tabaci to T. vaporariorum, the L2 instar at 18 °C, showing significantly more preference for B. tabaci than T. vaporariorum. In contrast, very few individuals were consumed from Aphis gossypii Glover (Hom., Aphididae), Frankliniella occidentalis (Pergande) (Thys., Thripidae) and Tetranychus urticae Koch (Acari, Tetranychidae). At 18 °C, a daily mean of 7.5–8.0, 6.6–9.0 and 6.7–8.1 B. tabaci as well as 5.3–6.4, 5.4–7.8 and 5.6–6.3 T. vaporariorum was consumed by L2, L4 and adult females, respectively, while at 30 °C, L2, L4 and adult females consumed a mean of 9.3, 8.8–9.7 and 8.3–9.7 B. tabaci/day as well as 8.3–9.0, 7.8–9.1 and 5.5–8.4 T. vaporariorum/day, respectively. S. parcesetosum L2 and L4 instars as well as adult females and males at both studied temperatures showed a significant tendency to avoid B. tabaci puparia after 5 days of parasitism by E. formosa and preferred to feed on unparasitized whiteflies. At 18 °C, the mean daily consumption was 8.7 and 0.2 (L2), 11.1 and 0.6 (L4), 12.1 and 1.0 () as well as 10.5 and 0.2 (), while at 30 °C the means were 15.9 and 0.5 (L2), 19.8 and 1.0 (L4), 18.9 and 1.2 () as well as 17.4 and 0.6 () from unparasitized and parasitized B. tabaci puparia, respectively.This paper is gratefully dedicated to Prof. Dr. W Schwenke on his 83rd birthday, 22 March 2004  相似文献   

2.
Pear lace bug, Stephanitis pyri (F.) (Heteroptera: Tingidae) is a pest of apple and pear trees and ornamental Rosaceae plants in Mediterranean countries and palearctic region. The aim of this study is to determine the effects of temperatures on S. pyri in the laboratory. Development and fecundity of S. pyri reared on apple leaves (Pyrus malus L.) were investigated at five constant temperatures (20, 23, 26, 29 and 32 ± 1°C) and a 16L:8D photoperiod. Longevity was determined to be 12.6 days at 32°C and 58.7 days at 20°C for females, and 9.7 and 37.7 days for males. Females laid 186.9 eggs per female with the highest number achieved during 28.5 days of oviposition period at 26°C. Female lifetime fecundity was reduced at 32°C (40.0 eggs per female). While the net reproductive rate (R 0) was highest at 26°C, the intrinsic rate of natural increase (r m ) was highest at both 26 and 32°C. The mean generation time (G) was estimated to be 27.2–78.4 days at 20 and 32°C, respectively. The longest development times for egg and total nymph stages were obtained as 22.0 and 24.9 days, respectively, at 20°C. S. pyri developed fastest from egg to egg in 24.3 days at 32°C. The lower developmental threshold (T 0) was 9.7°C and the thermal constant (K) was 517.3 degree-days for S. pyri. Thus, S. pyri is calculated to have 3.8 theoretical generations in Tekirdag. The optimum developmental temperature for S. pyri was 26°C.  相似文献   

3.
Laboratory experiments were conducted to evaluate the influence of repeated and delayed exposure to fresh codling moth eggs on the parasitism of Trichogramma cacoeciae Marchal and T. principium Sug. et Sor. The percentage survival of T. cacoeciae and T. principium females significantly declined as the number of exposure times increased (or as the females became older). The highest mean number of parasitized eggs and F1 progeny were recorded during the first day of exposure, after which they declined. However, the percentage mortality of parasitized eggs of T. cacoeciae and T. principium was negatively correlated with repeated exposure. When the exposure of T. cacoeciae and T. principium females to host eggs was delayed for 3 days after emergence, the percentage of oviposited females was not affected; however, the mean number of parasitized eggs, F1 individuals and the percentage mortality declined significantly. The current study provided essential information necessary to determine the optimal timing of parasitoid releases to increase the efficiency of T. cacoeciae and T. principium against codling moth.  相似文献   

4.
In the present study, the suitability of different predatory bug species, such as Dicyphus tamaninii Wagner, Macrolophus pygmaeus (Rambur), Orius albidipennis Reuter, Orius majusculus Reuter and Orius sauteri Poppius, for the biological control of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), were investigated. Development of the predatory bug species, their reproduction as well as their daily and total prey consumption over a 18-day period with F. occidentalis larvae or various stages of Tetranychus urticae Koch (Acari: Tetranychidae) individuals as prey species were studied during the experiments in the laboratory. In further experiments, the efficiency of D. tamaninii, M. pygmaeus, O. albidipennis and O. majusculus in controlling F. occidentalis under glasshouse conditions was investigated. Results showed that all the predators could develop under the experimental conditions with either F. occidentalis larvae or different stages of T. urticae as prey. When F. occidentalis larvae were offered as prey, the shortest duration of development was observed for O. albidipennis with a mean of 17.7 days, while D. tamaninii took the longest to develop with a mean of 36.3 days. With different stages of T. urticae as prey, the duration of development ranged from 19.3 days in O. albidipennis to 42.9 days in M. pygmaeus. Mean daily fecundity ranged from 0.8 eggs/female for O. majusculus to 2.2 eggs/female for O. sauteri with F. occidentalis larvae as prey and from 0.6, O. majusculus, to 2.3 eggs/female/day, O. sauteri, when different stages of T. urticae were offered as prey. Over the 18-day reproduction period, O. sauteri was the most fecund predatory species, laying a mean total of 31.6 and 31.3 eggs/female with F. occidentalis and T. urticae as prey, respectively. Daily consumption from F. occidentalis larvae ranged between 5.5 individuals consumed per day by O. majusculus and 29.1, by O. sauteri. When different stages of T. urticae were offered as prey, maximal consumption was observed in D. tamaninii with a mean of 29.0 individuals/day, while O. albidipennis consumed the least with an average of 8.1 preys/day. Over the 18-day prey consumption period, D. tamaninii consumed the highest mean number of 422.8 F. occidentalis larvae, while O. majusculus only consumed 98.8 larvae. Also, D. tamaninii had the maximum consumption of different stages of T. urticae with a mean of 522.4, while M. pygmaeus and O. albidipennis consumed the least, with an average of 146.1 and 146.0, respectively. The predatory bugs D. tamaninii, M. pygmaeus, O. albidipennis and O. majusculus significantly reduced the density of F. occidentalis on hybrids of Euphorbia milii, Serissa foetida and Saintpaulia ionantha in the glasshouse, which confirms their efficiency against this pest on different hosts under controlled climatic conditions.  相似文献   

5.
Non-choice laboratory experiments were conducted to evaluate the influence of host acceptance, previous rearing host, host age and the contact time between parasitoids and host on the efficacy of Trichogramma cacoeciae Marchal and T. principum Sug. et Sor. against the codling moth Cydia pomonella. The tendency of T. cacoeciae and T. principum females to attack the codling moth was similar to E. kuehniella, and it was not affected by the previous rearing host. T. cacoeciae showed a greater preference for codling moth eggs than T. principum. A high mean number of emerged F1 progeny was observed when both parasitoids were sequentially reared on codling moths. Codling moth acceptance, the number of parasitized eggs and the number of emerged progeny were higher when younger codling moth eggs were offered. The tendency of female parasitoids to oviposit remained unchanged when the contact time with the host was prolonged. When the contact time was increased, the number of parasitized eggs and emerged offspring was higher. The results showed that the codling moth fertility (egg hatch) was reduced when younger eggs were offered and when the contact time with the parasitoids was increased. T. cacoeciae was more efficient in reducing codling moth fertility. The current study provided essential information necessary to increase the efficiency of T. cacoeciae and T. principum against the codling moth.  相似文献   

6.
The predatory mite Typhlodromus pyri Scheuten (Acari, Phytoseiidae) has been reported as an important predator of the European red mite, Panonychus ulmi (Koch) (Acari, Tetranychidae) in apple culture and vineyards at below 25?°C. However, sufficient biological data was lacking on its efficiency at temperatures above 25?°C. Therefore, the purpose of the present laboratory work was to obtain experimental data on prey consumption during development as well as longevity and reproduction of T. pyri on apple leaf discs and in Plexiglas cells at constant temperatures of 25?±?2?°C and 30?±?2?°C with P. ulmi as prey.  相似文献   

7.
[目的]通过连续12 a对金斑喙凤蝶的野外调查观察,研究成虫活动规律,并利用仿生态养殖,观察金斑喙凤蝶卵和幼虫的形态特征与生活习性,研究其生物学特性,以期为金斑喙凤蝶研究与保护提供有效数据。[方法]根据2004—2012年对金斑喙凤蝶成虫活动规律的观察研究,2013—2015年,在金斑喙凤蝶成虫活动期,采用样线踏查的方法,自海拔450 m往山顶海拔1 200 m搜索,调查视野内木兰科植物分布情况,寻找卵和幼虫,收集后带回驻地进行仿生态养殖,观察其形态特征和生活习性。[结果]金斑喙凤蝶在九连山为一年二代,以蛹越冬,第一代成虫发生期为4月上旬至5月中旬,第二代成虫发生期为8月下旬至9月中旬;2013年在木兰科植物金叶含笑上发现卵和幼虫,2014和2015年在深山含笑上发现卵和幼虫,深山含笑为新发现寄主植物,目前除九连山外尚未有报道;幼虫5龄,各龄级幼虫差异较大;预蛹成蛹经历两次蜕皮过程,这是金斑喙凤蝶研究中的一项重大发现。[结论]1)金斑喙凤蝶卵和幼虫的分布与寄主植物分布密切相关,且对生境质量有较高要求,成虫活动范围主要在寄主植物分布范围及其周边;2)金斑喙凤蝶选择生长良好的金叶含笑和深山含笑叶片上产卵,或嗜食深山含笑;3)温度、湿度等环境因子对卵的孵化、幼虫的生长发育以及化蛹和羽化影响较大;4)金斑喙凤蝶雌蝶少,卵孵化率低,幼虫发育历期长,幼虫成活率低,化蛹和羽化率低等是导致其种群数量稀少的主要原因。5)据查,目前尚未有其它蝶类化蛹过程中经历两次蜕皮的报道,预蛹化蛹蜕两次皮是金斑喙凤蝶异于其他蝶类的特殊现象。  相似文献   

8.
Classic biological control is generally understood as an environmentally safe practice of insect pest management. We investigated the overwintering abilities of Trichogramma brassicae Bezd. and T. cacoeciae Marchall in Tekirda Turkey. Parasitized eggs of Ephestia kuehniella Zell (Lep.: Pyralidae) by T. cacoeciae and T. cacoeciae were exposed under outdoor conditions between 17 August and 9 October. Emergence of T. brassicae and T. cacoeciae for the five exposure dates occurred in the same year. An emergence of 99% was observed in the following offspring for all of the tested parasitoid species exposed on 17 September. For eggs that were parasitized later than 9 November 2003, the emergence of parasitoids was in spring, on 19 March 2004. We found that T. brassica and T. cacoeciae were able to overwinter successfully on E. kuehniella. Fecundity of T. brassicae and T. cacoeciae females that overwintered on E. kuehniella was significantly different from the fecundity of control females that were reared under optimal conditions at 25°C. Our results demonstrate that the egg parasitoids T. brassicae and T. cacoeciae are able to overwinter successfully in Turkey .  相似文献   

9.
The effectiveness of natural enemies against arthropod herbivores can depend on the characteristics of the plant on which they are found. The influence of the plant on the egg-laying behaviour of the promising whitefly predator, Serangium parcesetosum Sicard (Col., Coccinellidae) was examined in order to be able to use it effectively in biological control programs. The present work investigated the possible influence of the portion of the leaf on the number of eggs laid as well as the effect of plant species on the way in which eggs are deposited by S. parcesetosum. The experiments were conducted on cucumber and cotton leaves with Bemisia tabaci (Genn .) (Hom., Aleyrodidae) as prey in the absence and presence of a natural enemy, the lacewing, Chrysoperla carnea (Stephens) (Neur., Chrysopidae) at two different temperatures. The results showed that at 18°C, S. parcesetosum females significantly preferred to lay their eggs between the veins and close to the veins of cucumber leaves, mean of 10.1 and 7.5 eggs, in the absence of C. carnea, respectively, while in its presence significantly more eggs were deposited close to the veins and close to the petiole. On cotton leaves, close to the petiole, a mean of 8.4 eggs in the absence of the lacewing, as well as close to the veins, mean of 6.3 eggs in the presence of the lacewing, were found to be the most suitable leaf portions for egg-laying. At 30° C, the females laid their eggs preferentially close to the veins of cucumber leaves in the absence and presence of C. carnea. On cotton leaves, S. parcesetosum females significantly preferred to lay their eggs close to the petiole, mean of 7.6 and 6.1 eggs, as well as close to the veins, mean of 6.2 and 8.7 eggs, in the absence and presence of the lacewing, respectively. At both temperatures, the ladybird females laid their eggs singly on cucumber leaves in the absence and presence of C. carnea. While on cotton leaves, the females had a tendency to deposit their eggs together in the absence and presence of the lacewing, except at 30°C in its absence. Within the same plant species, significant differences were found in the total number of eggs laid by S. parcesetosum females on cotton leaves at 18°C as well as on cucumber leaves at 30°C in the absence and presence of the natural enemy. In addition to the effects of presence and absence of C. carnea, and where eggs were laid, some significant differences due to plant species was found at both temperatures.This article is dedicated to Prof. Dr Wolfgang Schwenke on his 84th birthday.  相似文献   

10.
I examined the adult potential fecundity of the bamboo gall maker,Aiolomorphus rhopaloides Walker (Hymenoptera: Eurytomidae), and its inquiline,Diomorus aiolomorphi Kamijo (Hymenoptera: Torymidae) by dissection just after emergence, and at death after rearing. Emerging females ofA. rhopaloides hadca. 80 mature eggs in their ovaries. The number of eggs at emergence and after death at rearing was not significantly different. However, emerging females ofD. aiolomorphi had no eggs in their ovaries but hadca 20 eggs at death after rearing. These results suggest thatA. rhopaloides is pro-ovigenic andD. aiolomorphi is synovigenic. Female body sizes of both species were positively correlated with the size of galls from which each emerged. Number of eggs in each species was also correlated with female body size, suggesting that gall size might be a good predictor of potential fecundity. This study was supported in part by a Grant-in-Aid for scientific Research (No. 11460068) from the Ministry of Education, Science, Sports, and Culture, Japan.  相似文献   

11.
We examined the effect of bark thickness of host trees on the ovipositional success ofSirex nitobei in relation to female body size by analyzing the relationships between female body-weight and ovipositor length and between bark thickness ofP. densiflora andP. thunbergii trees and oviposition proportion (the proportion of eggs laid to the potential female lifetime fecundity) of the woodwasp. The ovipositor length ranged from 6 to 14 mm and was correlated positively with the fresh body-weight of females. The bark thickness of host trees had no significant correlation with the oviposition proportion of large females of more than 100 mg f.wt, whereas it was correlated negatively with that of small females of less than 100 mg f.wt. Thus,P. densiflora, which has thinner bark as a whole thanP. thunbergii, may be more suitable for oviposition, especially for smaller females. Research Fellow of the Japan Society for the Promotion of Science. This study was supported in part by a Grant-in-Aid for Scientific Research from the Japanese Ministry of Education, Science, Sports, and Culture (No. 80003292).  相似文献   

12.
The entomophagous Serangium parcesetosum Sicard (Col., Coccinellidae) is an effective predator of some whitefly species. However, information on the influence of the preys host plant species on its biological and ecological characteristics is still lacking in the literature. Therefore, the current study focuses on the possible influence of three greenhouse and two field host plant species of Bemisia tabaci (Genn.) (Hom., Aleyrodidae) on the number of eggs laid by S. parcesetosum. In addition, because of the economic importance and widespread planting of cucumber in greenhouses and cotton in the field, these plants were selected for further investigation into the development, mortality, longevity and reproduction of S. parcesetosum at a high temperature in the laboratory. Results showed that S. parcesetosum was able to lay eggs on all five host plant species of B. tabaci, whether greenhouse or field plants. However, among the three greenhouse plant species studied, S. parcesetosum females laid the highest number of eggs on cucumber followed by tomato and then sweet pepper. Of the two field plant species, significantly higher numbers of eggs were laid on tobacco than on cotton. S. parcesetosum could develop either on cucumber or on cotton as preferable host plant species for B. tabaci. There were significant differences in mean developmental duration of larval instars of the same sex between both host plant species; the duration was significantly shorter on cucumber than on cotton. There were no significant differences for mean total developmental duration from egg to adult emergence between both host plant species within the same sex; females showed a mean of 15.9 days and males of 15.1 days on cucumber, while on cotton the means were 17.2 days for females and 16.2 days for males. Total mortality percentage of S. parcesetosum during development from egg to adult stage was lower on cucumber than on cotton, 20.6 and 23.8%, respectively. Longevity of S. parcesetosum varied according to host plant species and sex with a mean of 63.4 days for females and 50.3 days for males on cucumber, and 92.4 days for females and 52.5 days for males on cotton. On cucumber, mean period of oviposition of S. parcesetosum was significantly longer than on cotton. Mean total fecundity was significantly higher on cucumber than on cotton, with means of 97.7 and 31.0 eggs/female, respectively.  相似文献   

13.
The major bioecological characteristics of Bracon intercessor Nees (Hymenoptera: Braconidae), a parasitoid of the poplar clearwing moth, Paranthrene tabaniformis (Rott.) (Lepidoptera: Sesiidae), were studied from 1987 to 2003. Poplar shoots infested with P. tabaniformis larvae were collected in 11 localities in Bulgaria and examined in the laboratory, and infestations were also studied in the field. B. intercessor was recorded in seven localities and was found to be a gregarious external larval parasitoid of P. tabaniformis. Two generations of the parasitoid developed on the host. The first (summer) generation was associated with early and mid-stage (up to third instar) host larvae, and the second (overwintering) generation with third- to fifth-instar larvae. The average number of parasitoid individuals feeding on a host was 4.5 and 12.4 in summer and overwintering generations, respectively. The maximum number recorded was 25 individuals per host in the overwintering generation. B. intercessor overwintered as a mature larva on the host and completed its development in early spring. The adults from the overwintering generation appeared in April, about 1 month prior to emergence of P. tabaniformis. The life cycle of B. intercessor was not in close synchrony with the development of P. tabaniformis in the spring, but the parasitoid adults which fed on honey-sugar solution lived for up to 31 days (males) and 86 days (females), respectively. This suggests that, in the field, B. intercessor females eclosing in the spring could survive until the host larvae appear if nectar is available. Adults of the summer generation emerge from July to September when sufficient suitable host larvae are available. B. intercessor was responsible for 1.5% of the average mortality of the P. tabaniformis overwintering larvae. The host mortality caused by the summer generation of the parasitoid ranged from 3.2% to 5.8%.  相似文献   

14.
The rosy apple aphid Dysaphis plantaginea (Passerini) is a key pest in western European apple orchards; the economic damage threshold is so low that outbreaks cannot be forecasted. A mass rearing of the species on plantain (Plantago lanceolata L.) was initiated, with the aim to infest apple trees with either the autumn migrants, gynoparae and males, or the egg-laying females (oviparae). Here, data are presented about the propagation of the species on plantain, on the production of autumn migrants under laboratory conditions, and on the duration of juvenile development and reproductive capacities of both gynoparae and oviparae. Under long-day conditions (18 h light/day) on plantain, the thermal constant for the duration of juvenile development was 166 dd (day-degrees) above the lower development threshold of 5.1 °C, and daily larviposition amounted to 1.87 times the temperature (°C)minus 0.8, above a lower threshold of 4.3 °C. Between 32 and 36 larvae were produced by the young female before the first larvae become adult and their reproduction started to overshadow their mothers. A plant freshly infested with 12 reproducing females and transferred to short-day conditions (12 h light/day) yielded up to 5,000 autumn migrants, with males in the majority. The first gynoparae appeared after about 25 days at both 16 and 20 °C, and males appeared after 40 and 33 days, respectively. Young adult gynoparae produced most of their about ten offspring right after landing on apples, unless temperature was well below 15 °C. The duration of juvenile development of these oviparae appeared to be rather variable and their egg-laying so protracted that each of these females needs to survive several weeks to produce a handful of winter eggs. With reproductive capacities of up to 14 progeny/female for gynoparae and 7.4 for oviparae, release of one gynopara in the field could theoretically lead to the deposition of 100 winter eggs.  相似文献   

15.
Predictive models were developed for Cordia alliodora branch and Theobroma cacao branch or leaf biomass,based on branch basal areas (r2 0.79) but the model of C. alliodora leaf biomass, although significant, was of very low accuracy (r2 = 0.09) due to annual leaf fall. At age 10 years, shade tree stem biomass accounted for 80% of the total above-ground biomass of either tree. However, between the ages of 6 and 10 years, the biomass increment of T. cacao branches (3–4t.ha–1.a–1) was similar to that of the shade tree stems. During the same period, the net primary productivity was 35 and 28 t.ha–1.a–1, for the Erythrina poepigiana and and C. alliodora systems, respectively.Cocoa production under either of the shade trees C. alliodora or E. poeppigiana was 1000 kg.ha–1.a–1 (oven-dry; ages 6–10 yr). During the same period, C. alliodora timber production was 9 m3.ha–1.a–1 whilst the leguminous shade tree E. poeppigiana does not produce timber. Litterfall over the same 5 years, including crop and/or shade tree pruning residues, averages 11 and 23 t.ha–1.a–1, respectively. The main difference was due to E. poeppigiana pruning residues (10t.ha–1.a–1).Soil organic material reserves (0–45 cm) increased over 10 years from 198 to 240 t.ha–1 in the E. poeppigiana plots and from 168–184 t.ha–1 in the C. alliodora plots. These values, together with the productivity indices presented, provide evidence that the systems are sustainable.For economic reasons, the use of C. alliodora is recommended under the experimental conditions. however, on less fertile soils without fertilization, the greater biomass and hence nutrient return to the soil surface under E. poeppigiana, might make this the preferable shade tree.  相似文献   

16.
The influence of variable photoperiods on the feeding activity and fecundity of Galendromus occidentalis (Nesbitt) was studied on a diet of Tetranychus urticae Koch eggs. Starved G. occidentalis females were fed T. urticae eggs under ten 24-h light:dark regimes. Half of the tests started during photophase and the other half during scotophase. T. urticae eggs that were consumed and G. occidentalis eggs that were laid were counted at the end of each photophase and scotophase in a 24 h period. In general, G. occidentalis consumed more T. urticae eggs per h in the first phase of the experiment than in the second, regardless of whether the lights were on or off. In contrast to egg consumption, there were no statistical differences in the mean daily fecundity at the end of the 24-h periods. However, when the experiment was started during photophase, higher fecundity/h was encountered during scotophase than during the photophase. As a result, egg consumption rates were affected by photoperiods in both phases of the experiments. Logistic regression analysis revealed that variable photoperiods and egg consumption did not influence the fecundity of G. occidentalis.  相似文献   

17.
Experiments were conducted to elucidate how the oviposition activities ofSirex nitobei Matsumura could be affected by different conditions of the host trees, using logs from felled healthy trees and the dead and living trees ofPinus densiflora Sieb. et Zucc. According to days elapsed after tree-felling, the proportions of oviposition defined as the proportion of eggs laid to the potential fecundity of a female during her lifetime, could be divided arbitrarily into three groups. The proportions of oviposition on the logs within 0–3 days after felling,i.e fresh logs, varied greatly from log to log, and about half of female adults showed proportions of oviposition under 50% (mean ±SD: 39±32%). However, all the females that oviposited on the logs 4–24 days after felling,i.e. intermediate logs, invariably showed proportions of oviposition over 50% (88±1.5%). On the other hand, proportions of oviposition in most of the females that oviposited on the logs over 25 days after felling,i.e. old logs, were less than 50% (26±17%). The proportions of oviposition were significantly different between intermediate logs and old logs. The mean proportion of oviposition on living trees and that for dead trees were 45 and 58%, respectively. Thus,S. nitobei in the field would exhibit its preference for weakened trees ofP. densiflora as oviposition sites, as it did for the logs 4–24 days after felling in this study.  相似文献   

18.
The ethanol extracts obtained from both leaf and seed in the Thorn apple (Datura stramonium L.) (Solanaceae) were investigated for acaricidal, repellent and oviposition deterrent properties against adult two-spotted spider mites (Tetranychus urticae Koch) (Acari: Tetranychidae) under laboratory conditions. Leaf and seed extracts, which were applied in 167,250 and 145,750 mg/l concentrations, respectively (using a Petri leaf disc-spray tower method), caused 98 and 25% mortality among spider mite adults after 48 h. The simple logistic regression analysis showed that the independent variable, an increase in the dose of leaf extract was associated with a significant increase in the death rate of T. urticae females, but an increase in the dosage of seed extracts did not have a significant effect. Using probit analysis and estimating the parameters with a confidence limit of 95%, we determined the LC50 values of leaf extract to be 70,593 mg/l. According to Pearson’s χ2 test, mites showed the strongest run off to bean leaf surfaces sprayed with both leaf and seed extracts (in sub-lethal doses: <7,500 mg/l and <25,000 mg/l, respectively) and moved towards surfaces that had not been sprayed with extracts. Furthermore, repeated measures ANOVA indicated a significant difference between the number of eggs laid on unsprayed bean leaves compared to bean leaves that were sprayed with leaf and seed extracts at sub-lethal doses, 2,500 and 25,000 mg/l concentrations, respectively. These results suggest that D. stramonium extracts could be used to manage the two-spotted spider mite.  相似文献   

19.
Observations on life cycle, habits and characteristics ofBiston betularia (L.), which is a major pest infecting birch, were made in Daxing’an Mountain forest area, Heilongjiang Province during 1997–1998. In this area, the pest has one generation per year and overwinters as eggs in cracks of the lower part of stem. Adults emerge from mid-July to late August, and the damage of larvae occurs mainly in May and June. Life cycle table ofBiston betularia was given and control suggestions were made in this paper. Foundation item: This paper is part of Key Subject of Birch in State 9th Five-Year Plan. Biography: Sun Fan (1971-), female, lecture in Northeast Forestry University, Harbin, China Responsible editor: Chai Ruihal  相似文献   

20.
Despite the promotion of prunings as sources of nitrogen for crops, lack of synchronization between N mineralization from prunings and plant uptake remains a major limitation to the impact of prunings on crop yields. A laboratory and a field experiment were therefore carried out to determine the mineralization patterns of selected prunings and assess the potential that exists to improve synchrony by mixing prunings of different quality. The laboratory incubation experiment was conducted for 84 days to determine the C and N release patterns of prunings of different quality and the manipulation of the C and N mineralization trends by mixing prunings of different quality. High quality prunings were considered to be those with high CO2 evolution rates and mineralize N rapidly. The % C and % N released in 84 days were highest for the high quality prunings of Tithonia diversifolia (70% and 30% respectively) and least for the low quality prunings of Flemingia macrophylla (25% and –5% respectively). The medium quality prunings of Acacia angustissima and Calliandra calothyrsus had similar proportions of released C and N (about 40% C and 10% N). Different mixtures of T. diversifolia with other species showed contrasting influence on C release and N mineralization. Most mixtures released less C than that predicted, but in contrast most mixtures released N at a rate either matching or above the predicted. The % N released was strongly correlated with the polyphenol protein binding capacity (r2 = 0.53) and also with the % C released (r2 = 0.62). The field experiment was done for two cropping seasons to determine the effects of the prunings of these species and their mixtures on maize grain yield. The prunings were added at 5 t ha–1 and incorporated into the top 15 cm by hand hoeing in the first season and their residual effects were monitored in the second season. Medium and low quality prunings produced significantly (p < 0.05) higher maize grain yields in the first season ranging between 2.4 t ha–1 and 3.4 t ha–1 compared with T. diversifolia which produced 1.7 t ha–1. This suggested better synchrony in N release and uptake by maize with medium and low quality prunings compared with high quality prunings. The only mixture that indicated improved synchrony was the mixture of T. diversifolia and C. calothyrsus. This study showed that mixing prunings of different quality produce different patterns of N mineralization, some of which were unexpected and had a potential for improving N synchrony.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

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