Functional response of Tetrastichus gallerucae (Hym: Eulophidae) to different densities of the elm leaf beetle eggs,Xanthogaleruca luteola (Col: Chrysomelidae)

The elm leaf beetle is often considered as much of an indoor nuisance as a garden pest since large numbers of adults migrate into homes seeking a protected place to overwinter. Outdoors, both adults and larvae feed on the emerging leaves of virtually all species of elm trees, leaving skeleton zed foliage in their wake. Repeated severe infestations can markedly weaken a host tree, making it susceptible to other insects and diseases. The elm leaf beetle does not transmit the well-known Dutch elm disease, which is carried by another insect than elm bark beetle. The functional response of Tetrastichus gallerucae bees, that is the most important natural enemy of egg elm beetle Xanthogallerucae luteola, has been detected in Kerman province. The experiment was carried out in the growth room under conditions of 25 ± 1°C, 60 ± 5 RH and 16L:8D. Every female bee was exposed for 24 hours at densities of 2, 4, 6, 8, 10, 12, 16, 20, 30 and 40 eggs of elm leaf beetle. Every density had 10 repetitions. The results showed that T. gallerucae has the second type of functional response. The searching efficiency and the handling time of T. gallerucae was 2.63 and 0.114 on the eggs of elm leaf beetle and 2.193 and 0.112 on the eggs of hostess with diluted honey.     

Host location in Oomyzus gallerucae (Hymenoptera: Eulophidae), an egg parasitoid of the elm leaf beetle Xanthogaleruca luteola (Coleoptera: Chrysomelidae)

Eggs of the elm leaf beetle Xanthogaleruca luteola are often heavily attacked by the chalcidoid wasp Oomyzus gallerucae. We studied the chemical signals mediating interactions between the egg parasitoid, its host, and the plant Ulmus campestris. Olfactometer bioassays with O. gallerucae showed that volatiles of the host-plant complex attract the parasitoid. In order to determine the source of attractive volatiles within this host-plant-complex, we tested separately the effect of odours of eggs, gravid elm leaf beetle females, faeces of the beetles and elm twigs (with undamaged leaves and leaves damaged either mechanically or by feeding of the beetles). Odours of faeces of the elm leaf beetle were attractive, whereas neither volatiles from eggs nor from gravid females acted as attractants. Volatiles from undamaged or damaged plants did not elicit a positive reaction in O. gallerucae, whereas volatiles from feeding-damaged plants onto which host eggs had been deposited were attractive. This latter result suggests that it is not feeding but deposition of host eggs onto elm leaves that induces the production of plant volatiles attractive to the egg parasitoid. Investigations of the search patterns of O. gallerucae within the habitat by laboratory bioassays revealed that the egg parasitoid encounters host eggs by chance. Contact kairomones from faeces were demonstrated to be important in microhabitat acceptance, while contact kairomones isolated from the host eggs are relevant for host recognition. Received: 12 February 1997 / Accepted: 29 April 1997     

Specificity of chemical cues used by a specialist egg parasitoid during host location

Plant synomones and host kairomones are known to guide the egg parasitoid Oomyzus gallerucae to its specific host, the elm leaf beetle Xanthogaleruca luteola (= Pyrrhalta) (Muller) feeding upon elm leaves (Ulmus spp.). In this study, we investigated whether the activities of these plant synomones and kairomones are specific for the plant and herbivore species, respectively. Olfactometer and contact bioassays were used. In habitat location, O. gallerucae (Fonscolombe) is known to use synomones from Ulmus minor (Miller) that are induced by egg depositions of X. luteola. The attractiveness of such induced volatiles was shown to be specific both for the Ulmus species and the herbivore species depositing eggs. Neither leaves of U. glabra Hudson (= U. montana) carrying eggs of X. luteola nor leaves of U. minor (= U. campestris = U. procera) carrying eggs of the chrysomelid species Galeruca tanaceti L. emitted attractive synomones. O. gallerucae is also known to be attracted by volatile kairomones from faeces of X. luteola feeding on U. minor and to show prolonged antennal drumming when contacting substrates contaminated with these faeces. The kairomonal activity of the faeces was proved to be independent of the Ulmus species, since also faeces from elm leaf beetles feeding upon U. glabra emitted attractive volatiles. However, the faecal kairomones were specific for the herbivorous species, since faeces from a lepidopteran larva (Opisthograptis luteolata L.) feeding upon elm hardly elicited any antennal drumming in O. gallerucae. The egg parasitoid studied is known to recognize host eggs of X. luteola by contact kairomones extractable from the egg shell. O. gallerucae clearly differentiated between host eggs and eggs of another closely related chrysomelid species, Galerucella lineola L., as was shown by comparing duration of antennal drumming on host eggs and eggs of G. lineola.     

RearingTetrastichus gallerucae [hymenoptera: Eulophidae] for biological control of the ELM leaf beetleXanthogaleruca luteola

Tetrastichus gallerucae (Fonscolombe) was collected in southern France in 1985 and is being reared at the Division of Biological Control in Albany, Ca for use against the elm leaf beetle (ELB),Xanthogaleruca luteola (Müller) in northern California. This egg parasitoid can be reared easily by keeping the beetle eggs on a moist substrate to prevent desiccation and by inhibiting the growth of mold with air currents. A laboratory colony of ELB adults provides a constant supply of fresh eggs for the parasitoids. In 1985 and 1986 over 80,000T. gallerucae were released at 17 sites.      

Response of the elm leaf beetle to host plants induced by oviposition and feeding: the infestation rate matters

We investigated by olfactometry and feeding‐ and oviposition‐choice‐tests how the highly specialised elm leaf beetle, Xanthogaleruca luteola Müller (Coleoptera: Chrysomelidae), responds to conspecifically induced defences in the field elm Ulmus minor Miller (Ulmaceae). While egg deposition of the beetle induced elms to release volatiles attractive to the egg parasitoid Oomyzus gallerucae Fonscolombe (Hymenoptera: Eulophidae), feeding alone did not. In the present study, females of the elm leaf beetle showed preferences for the odours of twigs induced by low egg deposition and feeding over odours from uninfested twigs. In contrast, heavy infestation rendered elm odours less attractive to the beetles. Feeding and oviposition bioassays revealed an oviposition preference for leaves from uninfested twigs when compared to locally infested leaves. However, beetles preferred to feed upon systemically induced leaves compared to uninfested ones. The different preferences of the elm leaf beetle during host plant approach might be explained by a strategy that accounts for both gaining access to high quality nutrition and avoiding competition or parasitism.     

Patch-exploitation patterns in an egg parasite of elm leaf beetle

Eggs of elm beetle,Pyrrhalta luteola (Muller), normally occur in masses which can be viewed as discrete host patches in space and time. Analysis of>800 egg masses from 3 field sites in northern California revealed that the number of eggs/mass varied from 2 to>40 and that the imported egg parasiteTetrastichus gallerucae (Fonsc.) exploited a relatively large proported of the egg masses at certain times. The spatial relationship between parasitization and number of eggs/egg mass was assessed in 2 ways-i.e., for exploited masses only and for all masses combined (exploited+nonexploited). Percent parasitization was density independent in most cases for both data sets. It is suggested that both methods of analysis can provide patterns which are relevant to biological control of insect pests.      

Smelling the tree and the forest: elm background odours affect egg parasitoid orientation to herbivore induced terpenoids

Parasitic insects use herbivore induced plant volatiles as signals for host location. However, their responses to these volatiles in the background of natural habitat odours need further evaluation for developing successful biological control strategies. Field elms (Ulmus minor Miller (Ulmaceae)) release a blend of volatiles in response to oviposition of the elm leaf beetle, Xanthogaleruca luteola Müller (Coleoptera: Chrysomelidae), a major urban and forest pest in the USA and Australia. This induced blend attracts the beneficial egg parasitoid Oomyzus gallerucae Fonscolombe (Hymenoptera: Eulophidae). Our olfactory assays showed that an odorous background of non-attractive host plant volatiles from feeding damaged elms or (Z)-3-hexenyl acetate masks the attractive effect of the host-induced (E)-β-caryophyllene to O. gallerucae. Quantitative GC–MS analyses revealed decreased concentrations of (Z)-3-hexenyl acetate accompanied by highly increased concentrations of sesquiterpenes in oviposition and feeding treated elms compared to undamaged elms. This finding hints to how the parasitoid might distinguish between different odorous backgrounds. It is corroborated by the outcome of our field study in natural elm stands, where the egg parasitoid parasitized more host egg masses due to an artificially induced blend of elm terpenoids.     

Biological assessment of Tetrastichus brontispae,a pupal parasitoid of coconut leaf beetle Brontispa longissima

To control coconut leaf beetle, Brontispa longissima (Gestro), the pupal parasitoid Tetrastichus brontispae Ferrière was imported from Taiwan and its biology was studied in quarantine in Hainan, China. The parasitoid development includes an egg, three larval instars and three pupal stages. Its developmental time from egg to adult was 19.5±0.5 days under conditions of 24±2°C and 75±5% relative humidity (RH). Temperature had no effect on the sex ratio of offspring, but significantly affected the parasitism rate and reproduction. The parasitism rates were 98.07, 97.97 and 95.03% at 28, 24 and 20°C, respectively, whereas the parasitism rate was 52.18% at 18°C and 69.48% at 30°C, respectively. Furthermore, the parasitoids reared at 18 and 30°C produced fewer offspring than those at 20, 24 and 28°C, respectively. With the increase in temperature, developmental time decreased linearly from 46.19 days at 18°C to 17.10 days at 28°C. RH significantly influenced development, parasitism rate and the reproduction of T. brontispa. With the decrease of RH, developmental time increased from 22.94 days at 20% RH to 18.84 days at 95% RH. In contrast, parasitism rate and the number of offspring per female increased with the increase of RH. Though emergence rates between 50 and 95% RH were much higher than those between 20 and 35% RH, the sex ratios between 20 and 95% RH were not different. Photoperiod had no effect on parasitism, the number of offspring per female, emergence and the sex ratio of T. brontispae, but developmental time was significantly different for different photoperiods. Sucrose, honey and glucose significantly enhanced adult longevity, parasitism and the number of offspring per female of T. brontispae, but had no effect on the sex ratio and survival. Females of T. brontispae only parasitized fourth to fifth larval instars and 1–5-day-old pupae, but there was a significant difference in the number of offspring per female, development time, emergence and the sex ratio of offspring in different instars. These results showed that 1-day-old pupae, a temperature of 24–28°C and 65–95% RH were optimal for T. brontispae. These findings should be helpful in developing a production system to rear and release T. brontispae in large enough quantities to effectively control coconut leaf beetle.     

Is host plant choice by a clytrine leaf beetle mediated through interactions with the ant Crematogaster lineolata?

In the grasslands of northeastern Kansas, adult populations of Anomoea flavokansiensis, an oligophagous leaf beetle (subfamily Clytrinae), specialize on Illinois bundleflower (Desmanthus illinoensis) even though other reported host species commonly occur and are simultaneously available. We performed choice feeding tests to examine whether A. flavokansiensis adults have a fixed feeding preference for bundleflower. In choice tests, beetles ate similar amounts of bundleflower and honey locust (Gleditsia triacanthos). In addition, we measured fecundity and longevity of adults in no-choice tests to determine if adults were adapted solely to bundleflower. In no-choice tests, fecundity and longevity were no different for adults feeding on bundleflower and honey locust. We next examined the influence of host plant on the attractiveness of beetle eggs to ants. In northeastern Kansas, Crematogaster lineolata ants are attracted to A. flavokansiensis eggs and carry them into their nests where the larvae hatch and apparently reside as inquilines. C. lineolata exhibited a strong preference for eggs from female A. flavokansiensis that fed exclusively on bundleflower compared to eggs from females that fed exclusively on honey locust. Local populations of A. flavokansiensis in northeastern Kansas may specialize on bundleflower to increase the chances of their eggs being transported by C. lineolata ants into their nests. C. lineolata nests may serve as a predator-free and sheltered environment in which A. flavokansiensis eggs undergo embryogenesis. Received: 1 September 1997 / Accepted: 9 February 1998     

Production of Anagrus epos Girault (Hymenoptera: Mymaridae) on Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) eggs

Anagrus epos Girault (Hymenoptera: Mymaridae) is a natural enemy candidate for a classical biological control program targeting the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), in California. Little is known about the biology or ecology of A. epos when it utilizes GWSS eggs as a host. Here, we report the results of laboratory studies that describe the host age preference for oviposition, longevity of A. epos adults provided with different food sources, and developmental rates at six different constant temperature regimes. Anagrus epos is a gregarious parasitoid in GWSS eggs with up to 14 adults emerging from each GWSS egg. In choice and no-choice tests for oviposition, A. epos females successfully parasitized all developmental ages of GWSS eggs (1–8 days old). In choice tests, parasitism rates were significantly higher in 1-, 3-, 4-, and 5-day-old GWSS eggs than in 2-, 6-, 7-, and 8-day-old eggs. If provided with honey and water, honey only, water only, or no food or water, A. epos females lived on average 8.2, 4.7, 2.6, and 1.6 days, respectively. Anagrus epos required 294.1 degree-days above a lower temperature threshold of 12.4 °C to develop from egg to adult (eclosion). Our results provide baseline information useful in the development of an efficient parasitoid mass rearing program for A. epos release and evaluation in California.     

Effects of three mealybug species on the development,survivorship and reproduction of the predatory lady beetle Cryptolaemus montrouzieri Mulsant

The lady beetle Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) is an important predator of mealybugs. The development, survivorship, longevity and reproduction of C. montrouzieri feeding on three different mealybug species [Dysmicoccus neobrevipes Beardsley, Ferrisia virgata Cockerell and Planococcus minor (Maskell)] were investigated in the laboratory at 26 ± 1°C, 75-–90% RH and 14:10 (L:D) h photoperiod. Results indicated that, when feeding on different mealybugs, no significant differences were observed between developmental periods and survivorship of C. montrouzieri (from egg to adult), but differences were recorded between the sex ratios, preovipositional periods, adult longevities and reproduction of the differently treated lady beetle populations. The highest sex ratio (0.56), the longest preovipositional period (6.6 days) and adult longevity (84.8 days for females and 93.9 days for males), and the maximum fecundity (659.0 eggs/female) of C. montrouzieri were recorded when feeding on F. virgata. Moreover, C. montrouzieri had a high net reproductive rate (313.66), intrinsic rate of increase (0.0816) and finite rate of increase (1.085) when feeding on F. virgata. Results indicated that the population growth of C. montrouzieri may increase faster when feeding on F. virgata than feeding on either of the other two mealybugs.     

椰心叶甲啮小蜂的繁殖生物学研究

对椰心叶甲啮小蜂羽化、求偶、交配、产卵、繁殖现象进行了观察研究。结果表明,补充营养对雌蜂的寿命和繁殖力均有影响。没有补充营养的情况下,雌蜂的平均寿命为2.48 d,一生可产21.43粒卵;每天补充10%蜜糖水,且雌蜂与寄主(椰心叶甲初蛹)比例为1:3时,雌蜂平均寿命为13.43 d,一生可产53.6粒卵;每天补充10%蜜糖水,且雌蜂与寄主(椰心叶甲初蛹)比例为1:1时,雌蜂平均寿命为14.78 d,一生可产42.5粒卵。椰心叶甲啮小蜂对水椰八角铁甲蛹的寄生率为82.25%,平均每寄主出蜂量为12.24头。     

Adult feeding and lifetime reproductive success in the parasitoid Aphytis melinus

The diet of adult females of the parasitoid Aphytis melinus DeBach (Hymenoptera: Aphelinidae) includes host insects and sugar-rich foods such as nectar and honeydew. We compared the contributions of host feeding to longevity and fecundity in A. melinus females in the presence and in the absence of honey meals. First, we assessed the longevity of females that were not allowed to oviposit. While the longevity of females fed honey was significantly increased by host feeding (median ages were 30.5 days for host-fed females and 17 days for females not allowed to host feed), the lifespan of parasitoids not fed honey did not exceed 3 days for any individual and there was no effect of host feeding on longevity in this group. In the second set of experiments, we assessed the fecundity and longevity of females allowed to oviposit. We conducted two experiments, one in which honey was continuously available, and one in which honey was not available. In both experiments, daily observations were made of females that were either allowed to host feed or manually prevented from host feeding. In the presence of honey, host feeding significantly increased both fecundity and longevity, and in the absence of honey, parasitoids died within 2 days and host feeding had no significant effect on either fecundity or longevity. The lifetime fecundity of females fed honey but not hosts exceeded the initial egg complement by 60% on average. Approximately one host per day was used for host feeding whether honey was supplied or not, and each host-feeding meal contributed approximately 3.9 eggs to the lifetime fecundity of honey-fed females. In the last experiment, we compared the rate of egg resorption over a 36-h period in A. melinus females that were deprived of hosts and either fed honey or starved. While no egg resorption was detected in honey-fed females over this time period, starved females resorbed approximately 9 eggs. Thus, the availability of a sugar-rich food interacts strongly with host feeding in influencing longevity and fecundity and has a strong direct effect on egg resorption.     

椰心叶甲实验种群的生物学特性观察

自然温度条件下 ,椰心叶甲Brontispalongissima (Gestro) 1年可发生 3代以上 ,世代重叠 ,主要以成虫越冬。成虫平均寿命 1 5 6d ,最长达 2 3 5d ,雌雄性比为 1∶1 ;雌雄虫一生均可交配多次。成虫产卵期长 ,产卵不规则 ,单雌平均产卵 1 1 9粒 ,最多可达 1 96粒。飞行磨测定的初步结果表明 ,雌虫飞行能力比雄虫强 ,2 4h未取食成虫最远飞行距离可达 40 0多m ;成虫和幼虫均具有负趋光性、假死性。成虫 3～ 5d不取食、高龄幼虫 7d不取食仍存活。幼虫经历 4～ 5龄 ,在温度或寄主不适宜条件下 ,可进入 6～ 7龄 ,或提前化蛹 ,从卵到成虫羽化大约需 3 6～ 61d。     

Effect of Adult Experience on the Host-Location Behavior of the Aphid ParasitoidAphidius colemaniViereck (Hymenoptera: Aphidiidae)

We investigated the relationship between age and learning ability of femaleAscogaster reticulatusWatanabe, an egg-larval parasitoid of the smaller tea tortrixAdoxophyessp. (Lepidoptera: Tortricidae). Females 1, 3, 5, 7, 9, 11, and 13 days old had higher fecundity than 0-day-old females and could associate tea leaf extract with the host egg mass through oviposition. Experienced females 1 ≈ 13 days old walked more than 10 cm along an extract-treated line while exhibiting the antennating response. However, the learned responses of 0-day-old females was significantly lower [mean = 1.4 ± 0.8 (S. E.) cm] than that of older females (1 ≈ 13 days). In considering the relation between fecundity and the learned response, a low response in 0-day-old females could be due to a low propensity by them to learn cues associated with host eggs. Average longevity was 12.0 ± 1.5 days, but even 13-day-old females could oviposit a large number of eggs and learn to associate the tea leaf extract with host presence. This suggests that females can learn as long as they are able to oviposit. This learning ability would be advantageous forA. reticulatusfemales throughout their lives.     

Influence of adult diet on fitness and reproductive traits of the egg parasitoid Anagrus virlai (Hymenoptera: Mymaridae), a potential biocontrol agent against the corn leafhopper

Dalbulus maidis is the most important leafhopper pest of maize in the Americas. Anagrus virlai is an egg parasitoid commonly associated with the corn leafhopper. We evaluated whether the performance of A. virlai is dependent on different diets provided during 24 hr or throughout adult female lifetime. Additionally, functional response of A. virlai on D. maidis eggs using maize leaves containing honeydew plus honey was described. A. virlai is a mostly pro-ovigenic autogenic species whose females are able to parasitize eggs immediately after emergence. We found that wasps oviposit the majority of their eggs in the first day of their adult life. Realized lifetime fecundity and lifetime potential fecundity did not differ significantly among treatments, but longevity and egg production increased when honey was added to diet. Data were consistent with an intermediate functional response between type II and III, but closer to type II, indicating a high parasitism rate at low host densities and a decrease in the oviposition rate at high host densities, due to a possible egg limitation. Our results suggest that carbohydrate food sources (honeydew and honey) might not be the factor limiting reproductive success during the first 24 hr. Food supply, however, might influence egg maturation and survivorship of wasps, thus potentially enhancing biological pest control when hosts are scarce in the course of the first few days of adulthood.     

Egg resorption behaviour by the solitary egg parasitoid Anaphes nitens under natural conditions

We investigated under outdoor conditions and inside a climate chamber: (i) whether Anaphes nitens Girault (Hymenoptera: Mymaridae), an egg parasitoid of the Eucalyptus snout beetle, Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae), experienced egg resorption, and (ii) how various treatments (location, food, and/or host supply) and body size influenced egg load, egg resorption, fecundity, and longevity. One‐day‐old females were mated and randomly assigned to five groups: (A) honey + hosts, (B) water + hosts, (C) only honey, (D) only water, and (E) control females killed at emergence. We compared the egg load of the newly emerged females, which represent the control group (egg load = ovarian eggs present at emergence), with the lifetime egg load (i.e., ovarian eggs + emerged offspring + not emerged offspring) of the females with various host and diet treatments, by dissection of the ovaries to find evidence of egg resorption. All groups reared outdoors had fewer eggs than the control, while indoors there was no significant difference. Outdoors, starved but host‐provided wasps (B) experienced the highest reduction of the lifetime egg load (51%). Groups without access to food (B + D) resorbed more eggs than groups provided with honey (A + C). Females with honey and hosts (A) had the highest lifetime fecundity, but those with water and hosts (B) showed a higher daily realized fecundity. Host‐deprived females with access to food (C) attained the longest lifespan. Our results suggest that under stress conditions, such as low temperature and food shortage, A. nitens females practice egg resorption, probably to save energy.     

Life history and demography of Psyllaephagus zdeneki (Hymenoptera: Encyrtidae), a potential candidate for biological control of olive psylla,Euphyllura pakistanica (Hemiptera: Psyllidae)

Life history and demographic parameters of Psyllaephagus zdeneki Noyes and Fallahzadeh (Hymenoptera: Encyrtidae) were studied on its host the olive psyllid, Euphyllura pakistanica Loginova (Hemiptera: Psyllidae). Experiments were conducted in a growth chamber at 20±1 °C, relative humidity of 60±5%, and a photoperiod of 16:8 (L: D) hours. Four different olive cultivars (Fishomi, Shenge, Oil and Yellow) were used to test possible host plant influence on parasitoid performance. The pre-imaginal developmental period of female P. zdeneki varied from 24.96 (on Fishomi) to 26.34 (on Shenge) days, and for males from 21.63 (on Fishomi) to 24.44 (on Yellow) days. Adult female longevity differed significantly among the four cultivars, ranging from 12.46 (on Fishomi) to 14.97 (on Shenge) days. For each cultivar, adult female longevity was significantly greater than male longevity. Life table parameters showed survival rates (l _x ) in newly emerged females were 84.61, 82.25, 85.71 and 78.12% on Fishomi, Yellow, Shenge and Oil, respectively. Female egg deposition was highest on Yellow (138.4 eggs per female) and lowest on Fishomi (116.3 eggs per female). The highest and lowest intrinsic rate of increase were 0.28 (on Shenge) and 0.24 (on Oil), respectively. The mean generation time ranged from 14.6 (on Shenge) to 16.7 (on Oil) days. These results are discussed with respect to the potential impact P. zdeneki as a natural enemy of E. pakistanica, the most important pest of olive in the Fars province of Iran, as well as the influence of olive cultivar on parasitoid life table parameters.     

Potential for lab rearing of <Emphasis Type="Italic">Apanteles taragamae</Emphasis>, the larval endoparasitoid of coconut pest <Emphasis Type="Italic">Opisina arenosella</Emphasis>, on the rice moth <Emphasis Type="Italic">Corcyra cephalonica</Emphasis>

A lab rearing technique was standardised for Apanteles taragamae Viereck (Hymenoptera: Braconidae), the early larval parasitoid of the coconut leaf-eating caterpillar, Opisina arenosella Walker on the alternate host Corcyra cephalonica Stainton (Lepidoptera: Pyralidae). The parasitoid took 23.3 ± 3.2 days to complete the egg to adult period. Adult longevity for males and females was 15.3 ± 4.6 and 13.8 ± 4.6 days respectively. Fecundity was 14.8 ± 4.3 eggs per female. The percentage parasitism was 60.6 ± 5.7 on the alternative host C. cephalonica and 64.6 ± 5.5 on the natural host O. arenosella. Eight- to ten-day-old caterpillars were the ideal stage of C. cephalonica for rearing A. taragamae. The results indicated the amenability of rearing A. taragamae on C. cephalonica in the laboratory.     

Performance of Ooencyrtus kuvanae (Hymenoptera: Encyrtidae) on two host species,Halyomorpha halys and Philosamia ricini

The brown marmorated stink bug, Halyomorpha halys, is an invasive agricultural pest of fruit trees and vegetables. Egg parasitoids play a key role in the reducing of H. halys populations. Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) can parasitize H. halys and complete its life cycle in this host species. Many factors can influence this parasitoid–host relationship. Of these factors, we evaluated the effect of female age, exposure time, and host species on the biological characteristics and fecundity of O. kuvanae reared on eggs of H. halys as well as another previously known host Philosamia ricini (Lepidoptera: Saturniidae). In this study, we used a 3-year-old laboratory colony of O. kuvanae. Parasitism rates positively affected by exposure time in P. ricini. The highest parasitism rates were obtained in 5- and 7-day-old females of both hosts. The highest emergence rates were recorded on P. ricini for 5- and 7-day-old female P. ricini (81.8% and 84.8%, respectively). The development time of O. kuvanae ranged from 18.4 to 19.1 days on H. halys and 17.7 to 18.3 days on P. ricini. The longevity of O. kuvanae that were provided honey was 38.5 and 47.8 days on H. halys and P. ricini, respectively. The longevity of O. kuvanae that were not provided honey was 2.3 and 2.8 days on H. halys and P. ricini, respectively. The sex ratio was male-biased (36.5% female) on H. halys and female-biased (55.2% female) on P. ricini. Fecundity of O. kuvanae was 37.7 and 59.6 progeny per female for H. halys and P. ricini, respectively. The performance of O. kuvanae was lower when compared with its performance on the host P. ricini. Our results suggest that O. kuvanae has potential as new biological control agent for H. halys.