Effect of egg parasitoid density on the population suppression of Sunn Pest, Eurygaster integriceps (Hemiptera: Scutelleridae), and its resulting impact on bread wheat grain quality

The impact of the density of Sunn Pest egg parasitoids, Trissolcus grandis Thomson (Hymenoptera: Scelionidae), at three levels of Sunn Pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), infestation was assessed on bread wheat variety Cham 6 in screened cages in the field for percentage of egg parasitism and grain quality. Percent parasitism ranged from 60.1 to 83.9%. No statistically significant differences were detected at parasitoid densities of 1, 2, or 3 insects per square meter at Sunn Pest densities of 2 or 4 insects per square meter. The quality of grain collected from all Sunn Pest infested cages without egg parasitoids was unacceptable for baking purposes and was significantly lower than grain from both non-infested plots and plots where either two or three egg parasitoids were present. The abundance of egg parasitoids in Al Hassakeh province in Syria was also determined. Egg parasitism was observed 1 week after the initiation of Sunn Pest oviposition and ranged between 22 and 59% in non-insecticide treated fields, while no parasitoids were recovered from insecticide treated areas within the same region. The impact of feeding by Sunn Pest on different wheat stages indicated that only feeding prior to the spike stage does not affect the bread-making quality of the grain.     

Relationships between the emergence and oviposition of ectoparasitoid Spathius agrili Yang and its host emerald ash borer, Agrilus planipennis Fairmaire

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), (= A. marcopoli Obenberger), is an important bark beetle attacking ash trees (Fraxinus spp.). It is very difficult to detect and control because of its highly concealed life history. This pest mainly distributed in partial Asian countries (China, Japan, Korea, Mongolia) and Far East Russia, while in China it presented in Heilongjiang, Jilin, Liaoning, Shandong, Inner Mongolia, Hebei, Taiwan Provinces and Tianjin City, etc. The important timber species F. mandshurica and gardening tree F. velutina were damaged severely in northern China. Spathius agrili Yang (Hymenoptera: Braconidae) is an important ectoparasitic wasp of the EAB larvae. This parasitoid has the potential to use as an excellent biological control agent for suppressing populations of EAB. The differences of emergence date between overwintered S. agrili and its host, parasitism rates at different periods, relations between parasitism rates and host densities, and relationships between ovipositions of braconid wasp and body sizes of host larvae were studied using methods of regular surveys in forests and observations in laboratory. Results revealed that the emergence of S. agrili was more than one month later than that of its host. It suggests good synchrony between parasitoid emergence and host availability. The overwintered S. agrili emerged from mid June to mid August with the peak in July in 2003, and it lasted from late May till late July with the peak during late June to early July in 2004. While the EAB emergence period ranged from mid May to late May in 2003, it ranged from mid April to mid May in 2004 (in laboratory). The emergence date of parasitoid asynchronously inosculated with the optimum developmental instars of the earliest host larvae, which was the result of a long-term co-evolution between the two species. It was also suggested that the parasitoid S. agrili could be a specialized natural enemy for EAB. The natural parasitism rates on the whole gradually increased in field with time. The body sizes of host larvae, i.e. larval instar, affected the decision of parasitoid S. agrili to lay eggs or not. Under natural conditions, this parasitoid usually oviposited only on those host larvae with a prontum and body width more than 1.5 mm, and a body length in excess of 12 mm, i.e. the third or fourth instar larvae. These findings would consequentially contribute to the further successfully biological control of the trunk borer. __________ Translated from Acta Ecologica Sinica, 2006, 26(4): 1,103–1,109 [译自: 生态学报]     

The colonization preference and population trends of larval fig psylla, <Emphasis Type="Italic">Homotoma ficus</Emphasis> L. (Hemiptera: Homotomidae)

The colonization preference and population trends of larval fig psylla Homotoma ficus L. were studied in Bursa, northwestern Turkey, from March 2000 to July 2001. Homotoma ficus overwintered at the egg stage on terminal buds and lenticels of shoots. Larval emergence occurred on 30th and 11th March in 2000 and 2001, respectively. Degree-day (DD) accumulations since 1st January indicate that the emergence of first larvae averaged 47 DD based on the larval developmental threshold of 10.9°C. Although the population trends of Homotoma ficus larvae were affected by temperature and rainfall, there was only significant relationship between larval abundance and temperature. The first instar larvae significantly preferred the bottom and the inside stipule of leaves. The second instar larvae distributed not only on expanding green tissues but also on both the upper and lower surface of leaves corresponding to the fig bud development period. Third to fifth instars colonized significantly greater on the bottom of leaves compared with the stipule and upper surface. In addition, significant linear relationship was found between fig phenology and cumulative larval counts. The importance of the colonization preference of larval instars and the use of fig phenology as well as DD for timing of insecticide treatments are discussed.     

Host instar suitability of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> (Genn.) (Hom.: Aleyrodidae) for the parasitoid <Emphasis Type="Italic">Eretmocerus mundus</Emphasis> (Hym.: Aphelinidae)

Efficient use of parasitoids in pest control depend on the knowledge of the biological relationships between host and parasitoid. Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) is one the most important natural enemies of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) that is found in fields and greenhouses in Adana, Turkey. Although more studies have been done to determine the relationships between E. mundus and B. tabaci, the differences among strains of E. mundus could have important biological concequences. In this study, biological characteristics of native population of E. mundus parasitization of B. tabaci (Q biotype) were determined using bean plants Phaseolus vulgaris (L.) at a constant temperature of 25 ± 1°C, relative humidity 70 ± 10% and 16:8 (L:D) photoperiod regimen. All B. tabaci nymphal instars were parasitized by E. mundus, but the mean number of daily-parasitized nymphs was highest in the second instars (15.3). In addition, second instar females had the shortest mean development time (15.2 days). Mean development times of parasitoids obtained from first, second, third and fourth B. tabaci instars varied from 15.2 to 16.2 days and 15.2 to 15.9 days for female and male, respectively. Proportion of female (♀/♂+♀) varied from first (0.53) to second (0.34) host instars. Impact of results on potential biological control of B. tabaci was discussed through conservation native natural enemies.     

Timing and order of different insecticide classes drive control of Drosophila suzukii; a modeling approach

The spotted-wing drosophila, Drosophila suzukii Matsumura, is an invasive pest causing significant damage to soft skinned fruits. Control of D. suzukii is critical since there is no tolerance for infested fruit in the market. While most insecticides control one or more D. suzukii life-stages (e.g., egg, larvae, and adult), the impact of insecticides that are toxic to immature stages  is unclear on the subsequent generation of a field population. Insecticides were applied at field recommended rates on cherries and blueberries in the laboratory to determine immature D. suzukii mortality. Spinetoram, cyantraniliprole, malathion, methomyl, spinosad, and phosmet resulted in relatively high mortality of all immature life stages. Zeta-cypermethrin, cyclaniliprole, and fenpropathrin resulted in lower mortality of egg and all larval instars. Malathion was also applied to lowbush blueberries with different fruit sizes (small, medium, and large) in the laboratory and there was no statistical difference in mortality rates depending on fruit sizes. Mortality data from the laboratory experiments were used to parameterize a refined D. suzukii population model. The model revealed that the timing and order of different insecticide classes are important to control D. suzukii population. Model runs that included early applications of more effective insecticides resulted in high immature mortality and greater reduction of D. suzukii populations compared to treatments applied later.

     

环斑猛猎蝽生物学特性的研究*

据北京室内饲养观察，环斑猛猎蝽一年发生一代，以４龄若虫越冬。卵期９．９±１．１ｄ。若虫共５龄，历期３１５．０±４．９ｄ。成虫羽化后７－２５ｄ交配，交配后２２－２３ｄ开始产卵。描述了各虫态形态特征。记述了生物学特性。试验表明该虫是杨扇舟蛾、黄刺蛾、杨叶蜂、舞毒蛾、油松毛虫、黄褐天幕毛虫、刺槐蚜等多种林木害虫的捕食性天敌。     

Performance of two <Emphasis Type="Italic">Trichogramma</Emphasis><Emphasis Type="Italic">brassicae</Emphasis> strains under greenhouse and field conditions for biocontrol of the silver Y moth in spinach cultures

The suitability of Trichogramma brassicae Bezd. (Hymenoptera: Trichogrammatidae) to control the silver Y moth, Autographa gamma (L.) (Lepidoptera: Noctuidae) in spinach was investigated under greenhouse and field conditions. Two strains of T. brassicae were selected to study host searching efficiency and dispersal ability of the wasps on spinach. The experiments were conducted with defined release densities. The results show that T. brassicae strain I failed to locate host eggs in all experiments. In contrast, T. brassicae strain II females were able to locate 37% of the exposed egg clusters in the greenhouse within 48 h. Individuals colonised rapidly at least an area of 0.25 m². At distances up to 26 cm to the release point of the T. brassicae females, parasitization rate was 100%. Moreover, under field conditions silver Y moth eggs were exposed two times for 48 h on 12 experimental plots of 100 m² in two spinach fields. During the first exposure interval, i.e. 4 days after mass release of T. brassicae strain II, overall parasitization rates reached 20% on both fields. Furthermore parasitization rates still reached 16 and 19% during the second exposure interval, i.e. 9 days after natural enemy release, indicating a constant Trichogramma activity over time. Parasitization rates were highest in the close vicinity of the release point, i.e. 86%, whereas 6.5 m away the mean parasitization rate decreased to 3%. In conclusion results indicate a high potential of T. brassicae strain II as antagonist of A. gamma. Nevertheless the dispersal ability of T. brassicae strain II was limited, but adjustment of release densities and techniques might compensate this disadvantage.     

Reproductive strategies and food sources used by Acerophagus n. sp. near coccois, a new successful parasitoid of the invasive mealybug Phenacoccus peruvianus

Phenacoccus peruvianus Granara de Willink (Hemiptera: Pseudococcidae) is a new invasive mealybug that causes important damages in ornamental plants in urban landscapes and nurseries in Southern Europe. Recently, a new species of genus Acerophagus Smith (Hymenoptera: Encyrtidae) has been recorded as the main parasitoid of P. peruvianus in Spain, displacing the native parasitoid Leptomastix epona Walker (Hymenoptera: Encyrtidae). In this work, we have determined some traits of the reproductive and feeding strategies of Acerophagus sp.: fecundity, immature developmental time, host instar suitability, and preference when parasitizing P. peruvianus, and the effect of natural occurring sugar sources on adult longevity. Acerophagus sp. egg load reached its maximum when it was 5 days old. Second and third nymphal instars and adults were suitable for parasitism and immature development (efficient encapsulation was low). Immature development lasted between 20 and 22 days. Acerophagus sp. developed as a solitary parasitoid in the second instar and as a gregarious parasitoid in older instars (2–4 parasitoids per host). All the emerged offspring were females. Acerophagus sp. always preferred older instars when different host instars were available. Finally, adults lived more than 20 days when fed on honey, but they lived fewer than 3 days when fed on naturally occurring sugar sources (host honeydew and host plant flowers, Bougainvillea glabra). The consequences of these characteristics on biological control and parasitoid rearing are discussed.     

Catch me if you can: novel foraging behavior of an egg parasitoid,Gryon gonikopalense,against the stinkbug pest,Bagrada hilaris

Journal of Pest Science - Host detection and parasitism by egg parasitoids involve host chemical recognition, spatial overlapping, and the ability to overcome physical barriers. Within the context...     

柘树背索叶蝉生物学特性及防治

报道危害柘树的新害虫柘树背索叶蝉Pediopsis cudraniaeCai et Wang,首次记述卵及若虫形态特征、生活史及生活习性,进行了防治试验。该虫在山东省商河1 a发生1代,以卵在柘树枝条内越冬,4月中旬开始孵化,若虫刺吸嫩梢、叶片。若虫期用吡虫啉3 000倍液喷雾,防治效果良好。     

油茶尺蛾生物学特性的研究

油茶尺蛾是近年来广东省中山市阔叶混交林内出现的重要害虫。通过室内外饲养观察,结果表明,油茶尺蛾在广东省中山市1年发生1代,以蛹在地表土层中越冬,蛹期历时约9个月。成虫趋光性弱。在室内,成虫平均寿命约8d,最高产卵量可达1700粒;卵期平均22．1d;幼虫共6龄,幼虫期平均58．2d。     

Effects of gamma radiation on the Mediterranean flour moth, <Emphasis Type="Italic">Ephestia kuehniella</Emphasis>, eggs and acceptability of irradiated eggs by <Emphasis Type="Italic">Trichogramma cacoeciae</Emphasis> females

The sensitivity of the Mediterranean flour moth, Ephestia kuehniella, eggs in different stages of development to gamma irradiation was studied and the acceptability of irradiated eggs by Trichogramma cacoeciae females was examined. Eggs ranging in age from 1–24 to 49–72 h were exposed, at 24 h intervals, to gamma radiation dosages ranging from 25 to 400 Gy and effects of gamma radiation on egg hatch and adult emergence was investigated. In addition, the developmental rate of immature stages (larvae and pupae), resulting from irradiated eggs, to the adult stage was examined and the acceptance of irradiated eggs to T. cacoeciae females was evaluated. Results showed that the radio-sensitivity of E. kuehniella eggs decreased with increasing age. Egg hatch in 1–24-h-old eggs was significantly affected at 25 Gy dose and at 75 Gy dose, no egg hatch was observed. When irradiating 25–48-h-old eggs, however, egg hatch was less than 5% at 100 Gy dose, and eggs 49–72-h-old were more resistant; 50 Gy had no significant effect on egg hatch and 300 Gy did not completely prevent it. Irradiation also negatively affected survival to the adult stage. When 25–48-h-old eggs were irradiated, survival to the adult stage was completely prevented at 75 Gy dose and no survival was observed beyond 100 Gy dose in 49–72-h-old eggs. In addition, the rate of development of immature stages resulting from irradiated eggs was negatively affected. While more than 97% of control moths emerged within 30 days, this ratio decreased to 53 and 69% in 1–24 and 25–48-h-old eggs exposed to 25 Gy dose. Furthermore, irradiation positively affected the degree of acceptance of eggs to parasitization; irradiated eggs (≤49-h-old) were more acceptable to T. cacoeciae than cold-treated ones.     

马尾松毛虫寄生天敌与寄主数量关系的研究

1987～1988年,对湖南省洞口县马尾松毛虫种群密度及天敌寄生情况进行调查,发现寄生性天敌昆虫27种,重寄生者14种。据此,构造了松毛虫—寄生者系统食物网及营养级数量金字塔,对系统的稳定性进行初步分析表明,各代松毛虫的寄生天敌种类和寄生率均存在着差异。寄生率以第2代为最高;害虫种群变动趋势与天敌种类有关;寄生数量与寄主密度成正比;赤眼蜂、平腹小蜂的寄生率与卵块密度呈微弱负相关或无关,卵总寄生率与卵块密度呈轻微负相关,幼虫和蛹的寄生率与寄主密度无关。     

寄主树木、寄主和环境因子对松褐天牛深沟茧蜂寄生率的影响研究

[目的]松材线虫病是我国对森林危害和威胁最严重的病害,控制其传播媒介昆虫松褐天牛是防治松材线虫病的主要手段。作者发现的松褐天牛深沟茧蜂(Iphiaulax monochamusi Yang)是寄生松褐天牛中老龄幼虫的重要天敌。为明确松褐天牛深沟茧蜂的寄生率与寄主树木、寄主和环境因子的关系,开展了本研究。[方法]通过解剖46株松褐天牛危害致死的马尾松,调查了松褐天牛深沟茧蜂寄生率与马尾松、松褐天牛和环境因子之间的关系。[结果]调查研究表明:寄主树木的高度、胸径和树龄对松褐天牛深沟茧蜂寄生率没有显著影响,松褐天牛的数量对松褐天牛深沟茧蜂寄生率亦没有显著影响,而松褐天牛幼虫龄期和松褐天牛幼虫在树干上的位置显著影响松褐天牛深沟茧蜂寄生率。松褐天牛深沟茧蜂寄生率与松褐天牛龄期呈显著正相关,其偏好寄生3~5龄幼虫;就天牛在其危害寄主树木上的位置而言,松褐天牛深沟茧蜂偏好寄生马尾松主干上部和在韧皮部危害的松褐天牛幼虫,其对位于马尾松树干上部的寄主幼虫寄生率最高,达27.38%,对在韧皮部生活、危害的寄主幼虫寄生率为20.18%,显著高于位于木质部生活的寄主幼虫寄生率(5.46%)。逐步回归分析表明:影响松褐天牛深沟茧蜂寄生率的关键环境因子是寄主树木的坡位和其它天敌寄生率,其中,坡位与松褐天牛深沟茧蜂呈显著正相关,其它天敌寄生率与松褐天牛深沟茧蜂寄生率呈显著负相关。[结论]以上研究初步明确了松褐天牛深沟茧蜂的寄生率与寄主树木、寄主害虫和天敌之间的关系,为今后利用该重要天敌控制松褐天牛打下了基础。     

Establishment and expansion of a Thaumetopoea pityocampa (Den. & Schiff.) (Lep. Notodontidae) population with a shifted life cycle in a production pine forest,Central-Coastal Portugal

In 1997, a temporally shifted population of Thaumetopoea pityocampa (Den. & Schiff.), was recorded for the first time in a restricted area of the oldest National Pine Forest of Portugal—the National Pine Forest of Leiria. This new population larval development takes place during the summer (summer population—SP), while in the normal population it takes place during the winter (winter population—WP). Between 2000 and 2003, we assessed the distribution and expansion of the SP, and quantified the differences in population densities, mortality and major life history traits with the WP within the Leiria Forest. The SP occurred at higher population levels (5–35% attacked trees) in a large continuous area of young plantations with high tree density, the same area where it was initially discovered. These densities were higher than the ones recorded for the WP in any part of the forest (0–12%), although both populations coexist geographically. The temporally shifted population preferably attacked young plantations. It also expanded south, following the direction of the dominant winds during adult flight. SP had a lower fecundity than the WP, however it benefited from lower egg mortality due mostly to a low rate of parasitism. It also benefited from a lower mortality in the early larval instars leading to low levels of colony extinction. SP larvae take half the time compared to the WP larvae, to reach the same final mass, probably due to the fact that they develop under higher temperature and global radiation. Separated emergence timings of adults lead to an allochronic isolation of the two populations. However, if this might represent an allochronic speciation event has to await further ecological and evolutionary studies of the system.     

柳杉长卷蛾生物学特性及防治

柳杉长卷蛾在浙江嵊县１年２代，少见１代。以初孵幼虫在枯死针叶和虫苞内越冬。翌年４月上旬开始出现成虫，幼虫５龄，老熟幼虫在虫苞内化蛹。化学防治试验结果：溴氰菊酯、菊乐合酯、氧化乐果、甲胺磷４种农药，用喷雾、喷烟方法防治，效果均在８９．４％以上。     

Development, feeding and reproduction responses of Adalia fasciatopunctata revelierei(Mulsant) (Coleoptera: Coccinellidae) to Hyalopterus pruni(Geoffroy) (Homoptera: Aphididae)

This study was carried out to determine the development, survival and reproduction responses of Adalia fasciatopunctata revelierei (Mulsant) (Coleoptera: Coccinellidae) feeding on Hyalopterus pruni (Geoffroy) (Homoptera: Aphididae), using 20, 40, 80, 160 and 250 prey densities. All experiments were conducted at 25±1°C, 60±5% relative humidity, 16:8 light:dark under laboratory conditions. The average daily prey consumption of A. fasciatopunctata revelierei immatures and adults increased with increasing prey densities. Predation was not different for the larval stages at 80, 160 and 250 prey densities. The longevities of adult females were 35.67, 35.33, 49.00, 58.33 and 57.16 days when 20, 40, 80, 160 and 250 H. pruni were provided, respectively. The mean daily and total fecundity of A. fasciatopunctata revelierei increased with increasing prey densities. Females of A. fasciatopunctata revelierei feeding on H. pruni laid 89 eggs at 20 prey density and 301.67 eggs at 160 prey density. The search rate of females was higher than that of all larval instars; and the search rate of the fourth-instar larvae was higher than that of younger instars. Handling time decreased with development from larval stages to adult.     

广西博白桉树枝瘿姬小蜂生物学特性研究

通过野外调查和室内饲养观察,对桉树枝瘿姬小蜂的成虫羽化、生活史、越冬情况、年虫口变化、生活习性等生物学特性进行了初步研究。该虫在广西博白1 a发生4～5代,世代重叠,以4～5代虫瘿(含各种虫态)越冬,3—7月为成虫羽化高峰和扩散期,全年大部分时间均有成虫羽化。     

Overwintering of the egg parasitoids Trichogramma brassicae and T. cacoeciae (Hymenoptera: Trichogrammatidae) in the Thrace region of Turkey

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 .     

Larvicidal activity of Solanum villosum Mill (Solanaceae: Solanales) leaves to Anopheles subpictus Grassi (Diptera: Culicidae) with effect on non-target Chironomus circumdatus Kieffer (Diptera: Chironomidae)

Chloroform-methanol extract of mature leaves from Solanum villosum Mill (Solanaceae: Solanales) was investigated to establish its biocontrol potentiality under laboratory condition against larval forms of Anopheles subpictus Grassi (Diptera: Culicidae), the vector of human malaria. All the graded concentrations (30, 50, 100 and 200 ppm) showed significant (P < 0.05) larval mortality and results of regression equations revealed that the mortality rates were positively correlated with the concentrations of the extract (R ² close to 1). LC₅₀ values for all instars were between 24.20 and 33.73 ppm after 24 h and between 23.47 and 30.63 ppm after 48 h of exposure period. Significant changes in the larval mortality (F < 0.05) was also recorded between instars during single “ANOVA” analysis. This extract also demonstrated no toxicity to larvae of Chironomus circumdatus Kieffer (Diptera: Chironomidae) which were found to be present as most common non-target dipteran insect in the habitats of A. subpictus. Qualitative and chromatographic analysis of the solvent extract revealed the presence of carbohydrates, saponins, terpenoids, volatile oil, steroids, phenols and flavonoids as major bioactive phytochemicals.