Idiobiont Ectoparasitoid Research Articles

Biology and morphometric relationship of gall inducers Contarinia sp. and corresponding parasitoids for swollen galls of Nitraria sibirica pall.

Galls function as provide shelter for gall inducers, guarding them against their natural enemies. Previous research has illuminated the interactions between galls, gall inducers, and their corresponding parasitoids within various caltrop plants. However, less is known about these relationships within Nitraria sibirica, particularly regarding the efficacy of parasitism. Therefore, this study aimed to identify the morphometric relationships among the swollen galls, gall inducers, and their parasitoids. Two species of gall inducers and three species of parasitoids were obtained from the swollen galls of N. sibirica. The correlations of the parasitization indexes, the lifespan of gall inhabitants, and temperature and the morphometric relationships between the galls and their inhabitants were analyzed. The dominant gall inducer identified was Contarinia sp. (Diptera: Cecidomyiidae). Furthermore, it was observed that three solitary parasitoids attacked Contarinia sp. in the swollen galls, with only Eupelmus gelechiphagus acting as an idiobiont ectoparasitoid. The dominant parasitoids were Platygaster sp. and Cheiloneurus elegans at sites 1 and 2, respectively, with Platygaster sp. displaying greater abundance than C. elegans in the swollen galls. The lifespan of the gall inhabitants shortened gradually as the temperature increased. Moreover, the optimal number of gall chambers ranged from two to four per swollen gall with maximized fitness, which can be considered the optimal population density for the gall inducer Contarinia sp. Morphometric analysis exhibited a strong linear correlation between gall size and chamber number or the number of gall inhabitants, as well as a weak correlation between gall size and body size of the primary inhabitants of swollen galls. Our results highlight the importance of the biological investigation of parasitoids and gall inducers living in closed galls with multiple chambers and may pave the way for potential application in biological control.

Biological quality of Anisopteromalus calandrae (Hymenoptera: Pteromalidae) reared with cold-stored larvae of Lasioderma serricorne (Coleoptera: Anobiidae)

An effective storage method for larvae of the tobacco beetle Lasioderma serricorne (F.) (Coleoptera: Anobiidae) would be useful for rearing and studying its larval parasitoid Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae), which is an idiobiont ectoparasitoid. In this study, we observed the survival of L. serricorne larvae that were refrigerated under different conditions (stored at 7 °C, 10 °C, and 13 °C for 30, 45, 60, and 75 days) and the number of emerging A. calandrae under these conditions, aiming to determine the optimal temperature for L. serricorne larvae storage. Our results showed that 10 °C was the optimum temperature for storing L. serricorne larvae, with no significant differences recorded in the number of parasitoids that emerged from L. serricorne larvae that had been refrigerated for 75 days compared with the control. After refrigeration at 7 °C for 45 days, L. serricorne larvae were almost dead, with no parasitoid emergence, suggesting that dead host larvae were not used for rearing A. calandrae. Interestingly, when stored for more than 45 days at 13 °C, L. serricorne larvae developed abnormally and died, and the number of parasitoids that emerged was also significantly reduced. Subsequently, we tested the adaptive parameters of A. calandrae reared with L. serricorne larvae after cold storage at 10 °C for different periods, including development time, sex ratio, longevity, adult body length, and fecundity. These parameters were not significantly different from those of the control with the exception of fecundity, which indicated that progeny production on refrigerated hosts gradually declined with storage duration. In summary, A. calandrae could successfully parasitize and utilize L. serricorne larvae as hosts for long-term refrigeration at 10 °C for up to 45 days without considerable undesirable effects on offspring suitability. These results may have practical implications regarding the development of efficient mass-rearing systems for A. calandrae.

Assessment of fitness traits of pure and mixed crosses of Mastrus ridens populations to improve classical biological control of codling moth

Populations of natural enemies in classical biological control programs often undergo recurring bottlenecks during importation and rearing, which can result in lower genetic variability and fitness.Enriching colonies with wild individuals, multiple importations or combining populations from different origins may help reduce this problem. Mastrus ridens (Hymenoptera: Ichneumonidae), a gregarious idiobiont ectoparasitoid of codling moth (Cydia pomonella) larvae was introduced to New Zealand from laboratory colonies dating to the 1990s. To improve populations for release, individuals from a most recent collection were imported from Chile (CL). Tests were conducted to measure genetic diversity of the parental populations (F0) and fitness traits of pure and mixed combinations of NZ and CL populations for F0 and the F1 generations. Results showed several effects depending on the population origin. CL females and males in the F0 generation lived longer than NZ females and males. Offspring from a CL mother lived longer than those from a NZ mother, and F0 and F1 females from a CL mother parasitized more larvae than females from a NZ mother. Genetic diversity estimates of F0 CL and NZ populations were 24% and 17% heterozygosity, respectively, and the NZ population had a larger proportion of diploid males than the CL population. Thus, no improvement in reproductive output resulted by mixing NZ and CL populations, as hypothesized, but a maternal effect was found in this species. This study shows the importance of understanding and tracking imported populations' genetic diversity and fitness traits in classical biological control programs.

Eupelmus messene Walker, 1839 and E. microzonus Förster, 1860 as parasitoids of Aulacidea hieracii (Bouché, 1834) (Hymenoptera, Eupelmidae, Cynipidae)

In the southeast of European Russia, the gall wasp Aulacidea hieracii (Bouché, 1834) is attacked by ten parasitoid species, including Eupelmus (Eupelmus) microzonus Förster, 1860 and E. (Macroneura) messene Walker, 1839. Although both members of the genus Eupelmus Dalman, 1820 are idiobiont ectoparasitoids, they demonstrate different life-history strategies in respect to many bionomic features. Specifically, E. messene is represented by brachypterous thelytokous females which lay single eggs directly onto the host body. This species can parasitize both concealed and exposed larvae and pupae of A. hieracii, but fails to attack its primary parasitoids. On the contrary, arrhenotokous males and females of E. microzonus are fully winged. These parasitoids usually lay several eggs per host which are placed onto the wall of the host chamber and covered with a particular fibrous substance. E. microzonus never parasitizes pupae or exposed larvae, although it can readily attack concealed larvae of A. hieracii and its primary parasitoids. In addition, hibernating individuals of E. messene undergo obligatory larval diapause, but those of E. microzonus are able to develop without exposure to subzero temperatures. All these data collectively suggest that the former species is highly specialized to exploit A. hieracii as a host, whereas the latter one mostly exhibits the so-called morphotypical specialization. These different strategies allow E. messene and E. microzonus to coexist on the same host species, as a local specialist and a more or less evenly distributed generalist, respectively.

Two males, one female: triplet-style mating behaviour in the Darwin wasp Xorides ater (Gravenhorst, 1829) (Hymenoptera, Ichneumonidae, Xoridinae) in the Swiss Alps

The Darwin wasp Xorides ater is a solitary idiobiont ectoparasitoid of wood-boring beetle larvae. It occurs across the Palaearctic, and in Switzerland seems to be restricted to areas above 980 m altitude. Very little is known about its biology and behaviour. We here report three separate instances of a female X. ater mating simultaneously with two males, observed on the same occasion on a Picea abies woodpile near Lenk, Switzerland. Only two copulae that involved one male and one female were observed at the same time, which might indicate that this mating mode is rather common in X. ater. We illustrate our observations with photo and video material and compare it to mating behaviour known from other species of Darwin wasps.

Comparative study about the sublethal effects of chemical and botanical insecticides on the functional response of Habrobracon hebetor Say (Hym.: Braconidae) to larvae of Ephestia kuehniella Zeller (Lep.: Pyralidae)

In this research, we evaluated sublethal effects of five commercial insecticides of fenvalerate, propargite, buprofezin, dayabon and palizin which are used in chemical control of target pests of Habrobracon hebetor Say (an idiobiont and gregarious ectoparasitoid), on the functional response of this important biocontrol agent. First, 80 mated females of H. hebetor were treated by LC30 of selected insecticides for 24 h. Then, among them six wasps were selected and introduced to different densities of Ephestia kuehniella Zeller larvae (flour moth, an economical stored pest of cereals) for 24 h. The regression analyses based on Holling model indicated the functional response type II in the control, palizin and buprofezin and type III in fenvalerate, propargite and dayabon. Moreover, the highest and lowest attack rates were obtained in palizin and fenvalerate treatments, respectively. In addition, the treated wasps by dayabon and fenvalerate showed the shortest and longest handling times, respectively. Accordingly, palizin and dayabon due to the lowest negative effects on H. hebetor are compatible insecticides for combination with this biocontrol agent in integrated pest management.

The Stephanidae (Hymenoptera, Stephanoidea) of Iran with the description of a new species

Stephanidae (Hymenoptera, Stephanoidea) are solitary idiobiont ectoparasitoids of wood boring insect larvae. Here we present two genera, i.e., Afromegischus van Achterberg, 2002 and Foenatopus Smith, 1861, and five species, i.e., A. gigas (Schletterer, 1889), F. bisignatus Aguiar & Jennings, 2010, F. crispus Aguiar, 2010, F. nimaarkanii Ghafouri Moghaddam & Rakhshani sp. n. and F. prousti Aguiar & Turrisi, 2010 from Iran. Specimens were collected in southeastern Iran (Kerman and Sistan-o Baluchestan) from unknown hosts. Their morphological features and distribution are discussed in relation to the overall knowledge in the target and adjacent regions. Foenatopus nimaarkanii sp. n. is incorporated to the key for the identification of Foenatopus species with double spots on metasomal tergites.

Natural Parasitism of Diaphorina citri (Hemiptera: Psyllidae) Collected From Two Host Plants in the Apatzingán Valley, Mexico, by Tamarixia radiata (Hymenoptera: Eulophidae)

Tamarixia radiata (Waterson) (Hymenoptera: Eulophidae) is an idiobiont ectoparasitoid of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). This study evaluated natural parasitism of the different nymphal instars of D. citri by T. radiata on three different dates in 2015 at four sites with Mexican lemon (Citrus aurantifolia Swingle) groves and at one site with orange jasmine (Murraya paniculata [L.] Jacq.) plants in the Apatzingán Valley, Michoacán state. Different patterns of parasitism by T. radiata were observed among the different nymphal instars of D. citri, sites, and collection dates. No parasitism of first and second instars was observed, and it only reached up to 5.0% in third instars. In fourth and fifth instars, parasitism was highly variable (2-69 and 1-38%, respectively). In terms of the accumulated parasitism across host instars, the highest percentages were observed in the collections conducted in May in Crucero de Parácuaro (86%) and Antúnez (91%), and they were approximately 45% in the collections conducted on 23 March in Antúnez and on 10 April in Nueva Italia-2. In the remaining collections, parasitism was between 2 and 15%. Our results suggest that T. radiata is an important mortality factor for populations of D. citri; this could have potentially important implications for the biological control of D. citri and for the management of huanglongbing, a disease transmitted by D. citri, in citrus groves.

Limited protection of the parasitoid Pachycrepoideus vindemiae from Drosophila suzukii host‐directed spinosad suppression

AbstractLaboratory trials were conducted to determine whether the spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), puparium can provide an effective physical barrier to protect immature stages of the pupal parasitoid Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) from spinosad treatments. Spinosad insecticides are currently an important suppression strategy for D. suzukii in organically managed fruit orchards although they are well known to cause mortality in hymenopteran parasitoids. High adult P. vindemiae female mortality (83%) occurred within 24 h of exposure to D. suzukii pupae treated with 10 mg a.i. l−1 spinosad and female parasitoids did not avoid the pupae treated with similar low levels of spinosad in choice tests that included untreated pupae. Pachycrepoideus vindemiae develops as an idiobiont ectoparasitoid on host fly pupa within the sclerotized host puparium. Significant P. vindemiae survival and emergence was recorded when parasitized D. suzukii puparia were exposed to field treatment levels of spinosad; however, the parasitoid survival was dependent on the time of the spinosad treatment of the host post‐parasitization. Significant parasitoid survival occurred when the host puparia were treated at 2 weeks when the parasitoid was in the pupal stage but did not occur when the host puparia were treated at 1 week post‐parasitization, when the parasitoids were still in a larval stage. The parasitoid adults consumed or otherwise came in contact with residual degrading spinosad when they exited the treated host, and consequently high and low adult parasitoid mortality occurred when the adults emerged from puparia treated at 2 and 1 week(s), respectively. Our study indicates that generally the integration of P. vindemiae parasitism into a sustainable D. suzukii management program is not compatible with spinosad treatments, although P. vindemiae in the pupal stage inside sclerotized host puparia appear to be minimally impacted by spinosad treatments, provided that the spinosad degrades before parasitoid emergence.

Insights into food webs associated with the South American tomato pinworm

The complexity of both natural and managed ecosystems involves various forms of interaction among organisms. Two or more species that exploit the same resource can engage in competitive behaviours, usually referred to as intraguild interactions. These can be direct, i.e. one species feeds directly upon the competitor (intraguild predation) or indirect, e.g. when the dominant organism competes for a food source that another organism is feeding upon (kleptoparasitism). We investigated the potential for such interactions in a biological model composed by the South American tomato pinworm, Tuta absoluta, and three of its newly associated natural enemies: the zoophytophagous predator Nesidiocoris tenuis and the two idiobiont ectoparasitoids Bracon nigricans and Necremnus tutae. N. tenuis was shown (i) to scavenge on parasitised T. absoluta larvae and (ii) directly to attack and feed upon larvae of both parasitoid species, although at a higher percentage in the case of N. tutae. In the presence of the host plant, the predator reduced the emergence of both B. nigricans and N. tutae adults significantly. This study stresses the ecological success of a generalist predator over indigenous parasitoids attacking an invasive pest. Moreover, these findings provide potential elements for better design of biological control programmes against T. absoluta. © 2017 Society of Chemical Industry.

Terminal-instar larval systematics and biology of west European species of Ormyridae associated with insect galls (Hymenoptera, Chalcidoidea).

A systematic study of the genus Ormyrus (Chalcidoidea, Ormyridae) was conducted based on the morphology and biology of the terminal-instar larvae of ten west European species that are parasitoids of gall wasps and gallflies of the families Cynipidae, Eurytomidae and Tephritidae. The first detailed descriptions are provided of the terminal-instar larvae of these ten species using SEM images to illustrate diagnostic characters with systematic values. A key is provided for the identification of ormyrid larvae associated with galls in Europe, which is based particularly on characters of the head, mouthparts and mandibles. Although only limited informative variation in body shape was found, the setation of the head provided several characters of potential taxonomic value. The larval biology of the ten ormyrid species inhabiting different galls is also summarised. Although Ormyrus larvae are usually solitary idiobiont ectoparasitoids of the host larva of various gall-inhabiting insects, evidence of secondary phytophagy was observed in some species.

Honey and honey-based sugars partially affect reproductive trade-offs in parasitoids exhibiting different life-history and reproductive strategies

Adult dietary regimes in insects may affect egg production, fecundity and ultimately fitness. This is especially relevant in parasitoid wasps where many species serve as important biological control agents of agricultural pests. Here, we tested the effect of honey and sugar diets on daily fecundity schedules, lifetime reproductive success and longevity in four species of parasitoid wasps when reared on their respective hosts. The parasitoid species were selected based on dichotomies in host usage strategies and reproductive traits. Gelis agilis and G. areator are idiobiont ecto-parasitoids that develop in non-growing hosts, feed on protein-rich host fluids to maximize reproduction as adults and produce small numbers of large eggs. Meteorus pulchricornis and Microplitis mediator are koinobiont endoparasitoids that develop inside the bodies of growing hosts, do not host-feed, and produce greater numbers of small eggs. Parasitoids were reared on diets of either pure honey (containing trace amounts of proteins), heated honey (with denatured proteins) and a honey-mimic containing sugars only. We hypothesized that the benefits of proteins in honey would enhance reproduction in the ectoparasitoids due to their high metabolic investment per egg, but not in the koinobionts. Pure honey diet resulted in higher lifetime fecundity in G. agilis compared with the honey-mimic, whereas in both koinobionts, reproductive success did not vary significantly with diet. Longevity was less affected by diet in all of the parasitoids, although there were variable trade-offs between host access and longevity in the four species. We argue that there are both trait-based and association-specific effects of supplementary nutrients in honey on reproductive investment and success in parasitoid wasps.

Effect of parasitoid density on the timing of parasitism and development duration of progeny in Sclerodermus pupariae (Hymenoptera: Bethylidae)

The gregarious idiobiont ectoparasitoid, Sclerodermus pupariae Yang et Yao, is a natural enemy that parasitizes buprestid and cerambycid beetle larvae in China. In a recent laboratory study of mass–reared female parasitoids on larvae of the substitute host, Thyestilla gebleri, the subsequent offspring were widely released to control target pests. To develop cost–effective techniques for rearing parasitoids, and improve the parasitic efficiency of Sclerodermus pupariae, several parasitoid–host ratios have been investigated. However, the mechanism whereby increasing the density of inoculated female wasps on a host affects female parasitoid fitness (adult performance and progeny developmental duration) remains unclear. In the present study, we examined the influence of parasitoid density (one to eight female wasps per host) on the time to first attack, paralyzing time, pre–oviposition period and oviposition period of foundresses and developmental duration of offspring. We showed that the time to first attack, paralyzing time, pre–oviposition period and oviposition period of foundresses were significantly negatively associated with parasitoid density, but that developmental duration of progeny was only affected at the larval stage. An increase in the parasitoid density to more than three female wasps per host had no significant influence on the investigated parameters. Our results suggest that host nutrition was adequate, and intraspecific interaction enhanced the parasitic efficiency of wasps sharing a single host. Furthermore, it is known that a suitable parasitoid–host ratio can play an important role in promoting mutually beneficial behaviors which enhance adult performance.

Multiple Release of Two Different Hymenoptera Parasitoid of Leafminer Fly, Synergy or Competition

Abstract Leafminer fly Liriomyza huidobrensis Blanchard (Diptera, Agromyzidae) is a key pest on potato plantation. Due to of negative impact of calendar based of pesticide application on environment and farmer health, Biological control by releasing hymenoptera parasitoid is promising as an alternative control to solve the outbreak of leafminer fly. There are two important species of hymenoptera parasitoid in lefminer population Hemiptarsenus varicornis (idiobiont ectoparasitoid) and Digliphus isaeae. idiobiont ectoparasitoid). The research objective was to determine whether multiple releasing of two parasitoid in leafminer population had significant control of leafminer fly compared than single release. The results showed that multiple release caused competition between two different behaviors of Hymenoptera parasitoid. Mortality of leafminer fly was caused by H. varicornis higher than Opius sp. In multiple or single release. The present results suggest that field releases of D. isaea would not have a detrimental effect on the indigenous species, H. varicornis, and that D. isaea may be a “good” candidate to supplement biological control of L. huidobrensis.

Facultative gregarious development in a solitary parasitoid wasp,Dendrocerus carpenteri: larvae may share nutritional resources

Solitary parasitoids generally produce only one offspring per host. Dendrocerus carpenteri (Curtis) (Hymenoptera: Megaspilidae) develops as an idiobiont ectoparasitoid on prepupae and pupae of primary aphid parasitoids inside the mummified aphid host. Females normally deposit a single egg but superparasitize when suitable hosts are scarce. We show that facultative gregarious development may occur but is constrained by resource competition between larvae. The probability of more than one offspring surviving increased with the intensity of parasitism; an age difference of ≤9 h between older and younger first instars did not promote gregarious development. Two female parasitoids and, rarely, up to three male parasitoids could develop together. Average body size in terms of dry mass did not differ between singly developing females and the combined mass of two females sharing host resources, but the combined mass of gregarious males was greater than that of their singly developing counterparts. Females were 3× more likely to eclose from single than gregarious mummies. The amount of host resources available per larva declines with increasing clutch size, in turn causing a corresponding reduction of adult size and size-dependent fitness attributes. We suggest that competition for limiting host supplies may influence the transition from solitary to gregarious development and should be considered in models of clutch size evolution in parasitoid wasps.

Notes on three braconid wasps (Hymenoptera: Braconidae, Doryctinae)parasitizing oak long-horned beetle, Massicus raddei (Coleoptera:Cerambycidae), a severe pest of Quercus spp. in China,together with the description of a new species.

Three species of Doryctinae (Hymenoptera: Braconidae) parasitize larvae of oak longhorn beetle Massicus raddei Blessig (Coleoptera: Cerambycidae), a serious wood borer pest in North China. Rhoptrocentrus quercusi sp. nov., is described as a new species and Doryctes petiolatus Shestakov, as well as Zombrus bicolor (Enderlein). The three species are idiobiont ectoparasitoids, and may have potential for biological control of oak longhorn beetle.

The life history and host-searching behaviour of the aquatic parasitoid wasp Apsilops japonicus (Hymenoptera: Ichneumonidae), a parasitoid of the aquatic moth Neoshoenobia testacealis (Lepidoptera: Crambidae)

The life history and host-searching behaviour of Apsilops japonicus parasitizing the aquatic moth Neoshoenobia testacealis were studied in the field and in the laboratory in Japan. Moth larvae initially mine the floating leaves of the yellow water lily, later boring into the petiole and pupating in the petiole underwater. While the wasps did not attack leaf-mining larvae, they were idiobiont ectoparasitoids of the pupae or mature larvae of N. testacealis in the petioles. The wasps did not swim with their wings or legs when searching for hosts underwater, they walked down leaf petioles into the water. It is presumed that the wasps overwinter as adults. The laboratory observations suggested that the female wasps could not detect the host presence in the petiole from the floating leaves and they randomly searched for hosts by probing with their ovipositors underwater.

A New Species of Sclerodermus (Hymenoptera: Bethylidae) Parasitizing Agrilus planipennis (Coleoptera: Buprestidae) from China, with a Key to Chinese Species in the Genus

Abstract A new parasitoid reared from Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), Sclerodermas pupariae n. sp. (Hymenoptera: Bethylidae), is described from China. S. pupariae was reared from A. planipennis in China attacking velvet ash (Fraxinus velutina Torr. ), a tree native to North America. Life-history studies of S. pupariae in the field and laboratory indicated it is a gregarious idiobiont ectoparasitoid of pupa and larva of A. phnipennis and has up to five generations per year. Parasitism rate in the field was 13%. Adult wasps reared from single host pupa or mature larva ranged from 24 to 56 individuals. Based on laboratory rearing, the emerging adult female to male ratio was 22:1. The new parasitoid species has a high potential as a biocontrol agent for emerald ash borer. Diagnosis of the new species with comparisons to Sclerodermas harmandi (Buysson) and a key to Sclerodermas known in China are provided.

Responses of an Idiobiont Ectoparasitoid,Spathius galinae(Hymenoptera: Braconidae), to Host Larvae Parasitized by the Koinobiont EndoparasitoidTetrastichus planipennisi(Hymenoptera: Eulophidae): Implications for Biological Control of Emerald Ash Borer (Coleoptera: Buprestidae)

Understanding interspecific competition among insect parasitoids is important in designing classical biological control programs that involve multiple species introductions. Spathius galinae Belokobylskij and Strazenac, a new idiobiont ectoparasitoid from the Russian Far East, currently is being considered for introduction to the United States for biological control of the emerald ash borer, Agrilus planipennis Fairmaire, whereas Tetrastichus planipennisi Yang, a koinobiont endoparasitoid native to China, is another natural enemy that already has been introduced in the same program. In a laboratory study, we examined the potential interactions between these two parasitoids when they compete for the same emerald ash borer host larvae. In multiple-choice assays where healthy emerald ash borer larvae were presented along with emerald ash borer larvae previously parasitized by T. planipennisi at different times, S. galinae attacked host larvae already parasitized by T. planipennisi for up to 4 d, but not 8 d. However, parasitism rates were significantly lower in previously parasitized hosts as compared with healthy host larvae. In no-choice tests where S. galinae females were presented either with healthy emerald ash borer larvae or emerald ash borer larvae parasitized by T. planipennisi at several earlier time points, S. galinae again parasitized significantly more healthy host larvae than T. planipennisi-parasitized larvae. These results suggest that the ectoparasitoid S. galinae can discriminate between healthy host larvae and T. planipennisi-parasitized larvae, and competitive interactions between the two parasitoids are likely to be minimal if coreleased by the emerald ash borer biological control program.

Efficiency of host utilisation by coleopteran parasitoid

In insect larvae, optimising food utilisation with respect to available meals and time is essential for achieving maximum adult body size, which is a relevant proxy of fitness. We studied the efficiency of food conversion, body size, mortality, and development time in a solitary idiobiont ectoparasitoid, Brachinus explodens (Coleoptera: Carabidae), reared in the laboratory on the pupae of another carabid genus, Amara. The efficiency of conversion index (ECI – ratio of ingested to assimilated food) was, on average, 54.1±1.1% (n=76), with a minimum of 26.9% and a maximum of 81.6%. The rate of increase in biomass gained (Wgained) with biomass of the host was constant in females, but it decreased in males over the range of host body mass. Females, therefore, grew heavier from hosts of the same mass compared to males. Body length increased with the host mass and was correlated with Wgained identically for both sexes. Mortality was unaffected by the host mass, but it significantly increased below 20°C. In contrast, the development time of the feeding phase of the larva increased with the host mass at 20.3 and 23.7°C, but it remained unaffected at 26.9°C and in all three temperatures considering pupal development. Wgained increased with development time up to ca. 8days of larval feeding at 23.7°C. To our knowledge, our data are the first on food utilisation in solitary idiobiont coleopteran ectoparasitoids, and they present the highest values of ECI in insects.