Host discrimination ability in the tephritid parasitoid Psyttalia concolor (Hymenoptera: Braconidae)

Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) is a koinobiont larval-pupal endoparasitoid of many Tephritidae of economic importance. Little has been reported on the ability of females to discriminate between healthy and parasitized hosts, as well as parasitized versus superparasitized larvae. Two-choice bioassays were conducted to evaluate the preferences of P. concolor naïve females for healthy or single-parasitized/superparasitized C. capitata larvae, as well as the host discrimination ability among medfly larvae which had been superparasitized by the same wasp or by a conspecific one. Psyttalia concolor preferred to oviposit in a unparasitized C. capitata larva than in a self-parasitized one. Females also showed an innate ability to discriminate between larvae parasitized twice or only once, preferring the latter. This ability helps the female to optimise its oviposition decisions by deliberately avoiding superparasitized hosts, since it is known that they give a lower return in offspring number and quality than do singly parasitized hosts. Our findings contribute to a better knowledge of the P. concolor host location behaviour and also to improve its mass-rearing technique through a rational management of the host/parasitoid ratio and the host exposure time. Indeed, the proper setting of these parameters allows to reduce the fraction of single-parasitized and heavily superparasitized larvae and to enhance P. concolor rearing in terms of parasitoid offspring.     

Acute toxicity in laboratory tests of fresh and aged residues of pesticides used in citrus on the parasitoid Aphytis melinus

California red scale Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae) is a worldwide citrus key pest. One of the control strategies currently promoted in the Mediterranean basin is the augmentative release of the parasitoid Aphytis melinus DeBach (Hymenoptera: Aphelinidae). A clear understanding of the impact that pesticides commonly used in citrus have on this parasitoid is therefore essential to assure the efficacy of the method. The aims of this study were to evaluate the lethal effects of freshly applied and laboratory-aged residues of eighteen selected pesticides recommended in IPM for citrus on A. melinus adults. According to their toxicity on A. melinus, the pesticides could be divided in four groups. Etofenprox and chlorpyrifos were harmful and persistent; abamectin was moderately harmful and slightly persistent; dimethoate, chlorpyrifos-methyl, and spirodiclofen were slightly harmful and moderately persistent; and azadirachtin, etoxazole, fenbutaestan, hexythiazox, mancozeb, petroleum oil, pirimicarb, propargite, pymetrozine, pyriproxyfen, spirotetramat, and tebufenpyrad were considered harmless. The information presented here will help us to integrate A. melinus release within an IPM for citrus in which pesticides are still used.     

The side-effects of pesticides onDiaeretiella rapae, a parasitoid of the turnip aphid (Lipaphis erysimi)

Diaeretiella rapae (M’Intosh.) is an endoparasite of the turnip aphid,Lipaphis erysimi (Kalt.) with a wide geographical distribution. The four Pesticides Nogos 50 EC at 600 ml per acre, Dimecron 50 WSC, Monofos 40 WSC and Tamaron 600 SL at 500 ml per acre, used in practice for the control of this pest, were tested for their side-effects onD. rapae. The parasitoid was reared on pottedBrassica napus plants infested with aphid under laboratory conditions (22±2°C, 60–70% rel. hum., 16 h light and 8 h dark). In one test, adult female parasitoids were exposed to fresh pesticide residues on glass plates and in another test, the pupae within aphid mummies were directly sprayed. The results revealed that Dimecron 50 WSC, Nogos 50 EC and Monofos 40 WSC were harmful causing 100% mortalitv toD. rapae followed by Tamaron 600 SL (97% moderately harmful) after 24 hours of application, compared to no mortality in control, where only water was sprayed. Directly spraying of pupae with Dimecron 50 WSC and Nogos 50 EC reduced adult parasitoid emergence to 9 and 7%, respectively, Monofos 40 WSC and Tamaron 600 SL to 3% compared to 78% emergence for the control within one week of treatment. The results showed that none of the tested pesticides was safe toD. rapae and according to the International Organization for Biological Control (IOBC) further testing under semi-field and field conditions is recommended.     

Effects of different neem preparations in comparison to synthetic insecticides on the whitefly parasitoid Encarsia sophia (Hymenoptera: Aphelinidae) and the predator Chrysoperla carnea (Neuroptera: Chrysopidae) on cotton under laboratory conditions

The contact and feeding toxicity of NeemAzal T/S (EID Parry, Chennai, India) to the parasitoid Encarsia sophia (Girault & Dodd) was compared with three synthetic insecticides (chlorpyriphos, endosulfan and triazophos) against immatures and adult emergence. NeemAzal T/S (1.0%) at lower dose (200 mg/l) did not cause any effect on the emergence of E. sophia adults, but there was a significant reduction in emergence at higher doses (800 mg/l). Also, it did not show contact toxicity to adults of E. sophia, but there was a significantly high feeding mortality in a dosage dependant manner, whereas chlorpyriphos, endosulfan and triazophos showed high toxicity both by contact and feeding method. Three neem preparations registered in India, NeemAzal T/S, Nimbecidine (T. Stains, Coimbatore) and Godrej Achook (Godrej Agrovet, Mumbai) were tested against egg and larval stages of Chrysoperla carnea (Stephens) at three dosages, using a synthetic insecticide, triazophos 40 EC (200 mg/l), for comparison under laboratory conditions. The three biorationals did not induce any adverse effect on the hatchability of C. carnea eggs. The mortality of the first instars of C. carnea was not affected by any of the azadirachtin enriched formulations; however, at higher dosage of 800 mg/l these neem based products resulted in increased mortality of the first and second instar larvae of C. carnea relative to the untreated controls. Whereas, triazophos induced very high mortality rates (85.0, 89.0 and 81.5%) of all the three larval instars. The neem based insecticides showed a dosage-dependant effect on the larval instars of C. carnea. Thus, these biorationals show that there is a potential to use them in an IPM system, being safe for natural enemies of B. tabaci in cotton.     

Laboratory rearing of the solitary egg-larval parasitoid, Chelonus oculator Panzer (Hymenoptera: Braconidae) on a newly recorded factitious host Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)

Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is recorded as a new factitious host for the solitary egg-larval parasitoid, Chelonus oculator Panzer (Hymenoptera: Braconidae). A short biology and rearing method of the parasitoid on the new host were studied at 30±1°C, 60–70% relative humidity, with a photoperiod of 16:8 (L: D). Chelonus eclosed from 74.60% of parasitized hosts. No significant difference was found between development times of male and female parasitoids. Development of the parasitoid was completed in 28.14±0.47 days in male, and 28.87±0.58 days in female. However, a significant difference was found between adult sizes of male and female parasitoids. Adult dry mass was found 0.88±0.04 mg in male, and 1.99±0.11 mg in female. In addition, C. oculator was successfully reared from P. interpunctella in twenty generations with the explained method. Significant knowledge about biology of C. oculator is still lacking. However, the parasitoid can be candidate for future research as a biological control agent against some important lepidopteran pests, and P. interpunctella may be suitable factitious host for mass rearing of C. oculator.     

Bioecological characteristics of Bracon intercessor Nees (Hymenoptera: Braconidae) as a parasitoid of the poplar clearwing moth, Paranthrene tabaniformis (Rott.) (Lepidoptera: Sesiidae) in Bulgaria

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%.     

For sex and more: attraction of the tephritid parasitoid Psyttalia concolor (Hymenoptera: Braconidae) to male sex pheromone of the olive fruit fly,Bactrocera oleae

The braconid parasitoid Psyttalia concolor foraging for larvae of Bactrocera oleae (Diptera: Tephritidae) uses olfactory cues from the larval microhabitat. However, it could rely on the sex pheromones of adults of its host, since B. oleae mating leks usually occur on olive plants and a high number of infested fruits can be easily located in their close proximity. We quantified the behavioural responses of P. concolor towards different doses of the two major sex pheromone components of B. oleae, the female-borne 1,7-dioxaspiro[5.5]undecane (DSU) and the male-borne (Z)-9-tricosene (ZT). Results showed that P. concolor females and males were attracted only to the highest amounts of ZT (10 B. oleae male equivalents), regardless of the mating status. Wasps remained longer on the surfaces treated with high ZT amounts over the control. P. concolor females could exploit the ZT produced by lekking olive fruit fly males as a foraging kairomone. This could allow them to rapidly track B. oleae-infested olive plants, thus raising their chances to locate host larvae during their lifespan. On the other hand, the perception of ZT by P. concolor males could raise their chances to locate receptive females emerging from parasitised B. oleae pupae or also ovipositing in olive fruits. This study increases the knowledge of the reproductive biology of P. concolor, highlighting a case of chemical espionage in which a sex pheromone component from adult stages of the host is exploited both as a foraging kairomone by female parasitoids and as a sexual kairomone by male wasps.     

Studies on the parasitoid complex of Choristoneura murinana (Hbn.) (Lep.: Tortricidae) in Turkey

The parasitoid complex of Choristoneura murinana (Hbn.), a pest of Abies cilicica Carr., was studied in Isparta, Turkey. Shoots and needles of A. cilicica with C. murinana larvae and pupae were collected and examined under laboratory conditions in 2002 and 2003. As a result of this study, 14 parasitoid species of C. murinana were determined: Apanteles obscurus Nees. (Hym.: Braconidae), Brachymeria intermedia Nees (Hym.: Chalcididae), Mesopolobus mediterraneus Mayr, Mesopolobus dubius Walker, Pteromalus chrysos Walker, Pteromalus sp. (Hym.: Pteromalidae), Monodontomerus aereus Walker (Hym.: Torymidae), Itoplectis maculator (Fabricius), Apophua bipunctoria Thunberg, Triclistus globulipes Desvignes, Dirophanes maculicornis Stephens, Hyposoter sp., Dusona sp. (Hym.: Ichneumonidae) and Aprostocetus sp. (Hym.: Eulophidae). In the studied parasitoid complex, A. obscurus, B. intermedia and I. maculator were the most important in reducing pest numbers. The level of total parasitism of the C. murinana was 19.4% in 2002 and 22.3% in 2003.     

几种药剂对美国白蛾的毒力测定和防效对比

对几种药剂防治美国白蛾3龄幼虫进行了室内毒力测定、野外防治试验和野外残效期测定,7种药剂的室内毒力测定结果表明0.12%藻酸丙二醇酯对美国白蛾3龄幼虫的毒性最强(LC50=0.053 5 mg/L),其它依次为0.38%苦参碱(LC50=0.259 mg/L)、1.2%烟碱.苦参碱(LC50=0.574 mg/L)、1%甲维盐(LC50=0.78 mg/L)、1.8%阿维菌素(LC50=1.38 mg/L)、4.5%高效氯氰菊酯(LC50=2.58 mg/L)、5%桉油精(LC50=3.85 mg/L);野外防效试验的10种药剂对美国白蛾3龄幼虫均有很好的防治效果,最终死亡率均达到100%,药后12 h高效氯氰菊酯致美国白蛾3龄幼虫死亡速度最快,其次为烟参碱、桉油精、苦参碱、藻酸丙二醇酯、阿维菌素、甲维盐,3种仿生物制剂中5%杀铃脲击倒速度较慢;残效期以仿生物制剂类最为显著,3种仿生物制剂类残效期均为49d以上,其次为高效氯氰菊酯达到14 d左右,残效期最短的有1%甲维盐、5%桉油精、1.2%烟碱.苦参碱、0.38%苦参碱、1.8%阿维菌素和0.12%藻酸丙二醇酯均为7 d左右。为防止美国白蛾对单一药剂产生抗药性,多种药剂应轮换使用。     

Mass rearing of <Emphasis Type="Italic">Neochrysocharis formosa</Emphasis> (Westwood) (Eulophidae: Hymenoptera), a parasitoid of leafminers (Agromyzidae: Diptera)

A method for mass rearing the parasitoid Neochrysocharis formosa (Westwood) was developed, using the leafminer Liriomyza huidobrensis (Blanchard) as insect host, and the Phaseolus vulgaris L. bean as host plant. About 1,500 parasitoids per tray of 84 plants emerged from about 2,000 leafminer larvae; 70% of these were females. The most suitable release density of host was two pairs of leafminer adults per bean plant, and that of parasitoid was three pairs per 24 leafminer larvae. Adult parasitoids were harvested based on positive photo-tactic response with 94.5% efficiency. Plants were improved by trimming their tips to increase the leaf area. The trimming process increased the number of leafminer larvae by about 32%. Furthermore, nitrogen fertilization of plants overcame the size reduction of the insects due to continuous rearing. Rearing of leafminer under light—dark (16:8 h) cycle decreased the development period of larvae and pupae. In addition, it restricted the time and duration of larval emergence and adult eclosion. Storage of parasitoid males and females at 7 and 10°C ± 0.5, respectively, proved to be optimal. The fertility of the mass-produced parasitoids after 1 year of rearing reduced by about 23%, and the sex ratio shifted toward males. In conclusion, successful mass production of N. formosa was achieved through designing suitable rearing cage and an efficient harvesting device, improving the host plant, and determining the age and the conditions for cold storage of the parasitoid and its host. Next, we checked the characteristics of the mass-produced wasps to ensure the efficacy when used in the field.     

中国窄腹细蜂属的研究

本文记述了膜翅目窄腹细蜂科窄腹细蜂属（ＲｏｐｒｏｎｉａＰｒｏｖａｎｃｈｅｒ１８８６）的４个新种，建立了一个新异名．同时，首次描述了红腹窄腹细蜂（Ｒ．ｒｕｆｉａｂｄｏｍｉｎａｌｉｓＨｅｅｔＺｈｕ）的雄性．研究标本均采自湖南省，模式标本保存于中南林学院林学系昆虫标本室．     

白蛾周氏啮小蜂转主寄主的研究

白蛾周氏啮小蜂是美国白蛾的优势寄生性天敌。为了了解其在释放利用后能否保持高的种群数量 ,达到对美国白蛾的持续控制效果 ,研究了这种小蜂在林间的转主寄主。通过调查 ,明确了白蛾周氏啮小蜂在林间的转主寄主种类 ,并研究了这些寄主的年生活史和生物学特性 ,以及白蛾周氏啮小蜂在这些寄主中的寄生率和出蜂量、雌雄性比等。结果表明 ,白蛾周氏啮小蜂的寄主有 7种 :美国白蛾 ,大袋蛾 ,柳毒蛾 ,榆毒蛾 ,国槐尺蛾 ,杨扇舟蛾和桃剑纹夜蛾。白蛾周氏啮小蜂年发生 7代 ,而美国白蛾年发生 2代 (部分年份可发生 3代 ) ,小蜂除寄生这 2代(或 3代 )美国白蛾蛹外 ,其余各代在这些转主寄主蛹中寄生。这些转主寄主的蛹期和美国白蛾的蛹期在 1a的生长发育期中相互衔接 ,小蜂可转移寄生在这些寄主上 ,从而能够保持较高的种群数量 ,达到对美国白蛾的持续控制。对各地白蛾周氏啮小蜂在柳毒蛾和美国白蛾上的寄生情况比较分析 ,发现该小蜂在不同地点的寄生情况差异不显著 ,说明这种小蜂的分布比较广泛 ,种群数量比较稳定。研究还表明 ,绿化树木的多样性可以增加转主寄主的种类和数量 ,从而能够使小蜂保持较高的种群数量 ,达到释放后对美国白蛾的持续控制效果     

Residues on olives,oil and processing waste waters of pesticides used for the control ofDacus oleae (Gmel.) (Dipt., Tephritidae)

A study has been carried out on the presence of pesticide residues (deltamethrin, fenthion, formothion and their metabolites) on olives, oil and processing waste waters, after adulticide and larvicide treatments for the control ofDacus oleae (Gmel.). Deltamethrin was found to have a faster degradation rate than fenthion, leaving no traces on olives 18 days after treatment. Fenthion, on the contrary, was still present on the drupes at harvest (28 days after the treatment). Formothion was not found in definable quantities 3 days after treatment, while its metabolities, dimethoate and omethoate, were found on olives at harvest in levels of 4–23 ppb.     

榆少锤角叶蜂的研究

榆少锤角叶蜂是严重危害榔榆、白榆叶片的新害虫。该虫１ａ发生１代，老熟幼虫钻入杂灌草丛根际或疏松浅土层中结茧，以预蛹越冬。翌年３月下旬化蛹，４月上旬羽化交尾交卵，幼虫期为３２．７８±２．２７ｄ，每头幼虫平均取食量为２５９０３．８３±６７７８．５５ｍｍ２，５月下旬相继老熟下树结茧过夏越冬。成虫产卵主要在低矮小树或大树下层枝条叶片上。该虫体表光滑裸露，抗药性弱，只要防治时机恰当，一般农药均可取得良好效果。以５％氯氰菊脂、２．５％敌杀死１∶３０００或８０％敌敌畏、９０％晶体积敌百虫１∶８００为佳。     

中国扁叶蜂订正名录(膜翅目:扁叶蜂科)

本文报道中国扁叶蜂订正名录共计47种.其中阿扁叶蜂属Acantholyda 11种,腮扁叶蜂属Cephalcia 19种,华扁叶蜂属Chinolyda 1种,纽扁叶蜂属Neurotoma 2种,拟腮扁叶蜂属Pseudocephaleia 1种,爪扁叶蜂属Onycholyda 7种及扁叶蜂属Pamphilius 6种;并记载分布及多数种的寄主植物.     

Effect of Lecanicillium muscarium on Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae), a parasitoid of Bemisia tabaci (Hemiptera: Aleyrodidae)

Pathogenicity of Lecanicillium muscarium, against Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae), was investigated under laboratory conditions to determine if the fungal infection of the whitefly host can effect the survival, longevity and fecundity of female parasitoid. The results indicated that the number of parasitized larvae surviving a L. muscarium treatment after 6 days of oviposition decreased with increasing concentrations of L. muscarium and in later stages of development (12 days post oviposition) were not affected by fungal application. There were no significant differences on adult parasitoid survivorship after 7 days among all treatments. Maximum survivorship (73.33%) was observed for control and it was minimum (60%) at 1 × 10⁸ conidia/ml. L. muscarium showed a non significant effect on longevity and next offsprings of female parasitoids. The percentage emergence of parasitoids from the whitefly nymphs produced by the females emerged from treated pupae was almost similar. Maximum emergence (69.77%) was observed at 1 × 10⁶ conidia/ml and it was lowest (61.02%) at conidial concentration of 1 × 10⁸ conidia/ml. Maximum longevity of adult Eretmocerus sp. emerging from whitefly nymphs when treated after 12 days of postoviposition was observed for 1 × 10⁵ conidia/ml having a mean value of 5 days whereas the lowest longevity was 4.9 days observed at 1 × 10⁸ conidia/ml. The results mentioned above indicate that the interaction among biocontrol agents is positive to a greater extent with minimum risk hazards.     

Experimental release of a parasitoid, Doryctes yogoi Watanabe (Hymenoptera: Braconidae), onto Semanotus japonicus Lacordaire (Coleoptera: Cerambycidae) inoculated into live Japanese cedar trees (Cryptomeria japonica D.DON)

Release experiments of Doryctes yogoi Watanabe onto Semanotus japonicus Lacordaire larvae inoculated into Japanese cedar, Cryptomeria japonica D. Don, were conducted to clarify the role of the parasitoids in the mortality of S. japonicus and the efficiency of the parasitoid as a natural enemy of the beetle. S. japonicus larvae were inoculated into three types of samples: live trees, girdled trees, and logs, each of which was treated in three ways: D. yogoi was released into the sample, the sample was screened (excluding natural enemies), or the sample was used as a control. In live trees, more than 90% of the larvae were killed by resin flow, and the percentage of parasitism by D. yogoi was less than 6%. In girdled trees, most of the larvae were dead due to the resin in the trees, having survived inoculation as well as in live trees, but many larvae were parasitized by D. yogoi in dead trees like logs. The present study revealed three negative effects of resin flow on parasitism by D. yogoi in the live trees. First, most of the host larvae died before reaching a size suitable for parasitism. Second, parasitoid larvae were caught in the resin with their hosts and died. Third, the host-searching and oviposition of female D. yogoi were obstructed by resin flow on the surface of the trunk. The efficiency of D. yogoi as a natural enemy of S. japonicus is discussed.     

Additional diet of the parasitoids (Hymenoptera: Braconidae) and the parasitizing of the Elm Bark Beetle (Coleoptera: Scolytidae)

Supplementing the diet of Coeloides scolyticida, Dendrosoter protuberans and Ecphylus silesiacus (Hymenoptera: Braconidae) with Parker's diet and the nectars of melliferous plants: Daucus carota L., Sinapis alba L. and Stachys recta L. had a significant effect on longevity, reproduction, developmental rate, and parasitizing of Scolytus scolytus (Fab.), Scolytus multistriatus (Marsh.) and Scolytus pygmaeus (Fab.) (Coleoptera: Scolytidae). These values were considerably lower for wasps fed with the nectar of Sinapis arvensis L. and Trifolium repens L. and the lowest for those without dietary additives. Parker's diet had the most significant effect on the parasitoids and parasitizing of the bark beetles. Nectar of S. recta and S. alba proved most suitable for C. scolyticida and D. protuberans, while E. silesiacus using the nectar from D. carota flower significantly increased parasitizing of S. pygmaeus. T. repens flowers were not a suitable additive for the diet of parasitoids. The parasitoids without additives in their diet had shorter lives, shorter development, and were less effective in reducing host numbers. E. silesiacus wasps had the longest development, and C. scolyticida the shortest. Generally, the parasitoids of the second generation had a slightly prolonged development (1?–?2 days).