Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] in Israel

Only one species ofChelonus Panzer,Chelonus inanitus (L.), was found to be widespread in all areas of Israel. The parasitoid was particularly widespread in alfalfa fields but also was present in cotton, sugar beet, artichoke and corn. Spodoptera littoralis (Boisd) andS. exigua (Hbn.) were the main hosts ofC. inanitus although it might develop in other Lepidoptera species. A study of its population showed that adults were present in the spring, summer and autumn but not during the winter. In most cases the population density of the parasitoid appeared to be related to that of the hosts. Parasitism and sex ratio ofC. inanitus in alfalfa fields were studied. The number of males (average of 75%) was higher than that of the females. Percentage of parasitism in larvae ofS. littoralis andS. exigua reached up to 39.8% and 13.5% respectively. The parasitism values in eggs ofS. littoralis were up to 71%.     

Effects of a lipid-rich diet on adult parasitoid income resources and survival

Effectiveness of parasitoids as natural enemies in agro-ecosystems depends on key traits such as fecundity and longevity. Energy sources allocated into survival and reproduction can be mobilized from capital stores acquired during larval feeding, or from income resources through adult feeding. Adult parasitoids have a restricted diet consisting solely of carbohydrates and most species do not replenish lipid levels after emergence from their host. Here, we have adopted a novel approach that could improve pest elimination by parasitoids, in which we added different ratios of olive oil to the food of adults to reveal the potential of a lipid-rich diet to increase lipid levels and allocation into survival. Our results show that males of the parasitoid Cotesia glomerata had higher lipid levels when fed a diet containing a ratio of 90:10% honey to olive oil when compared to males at emergence and males fed honey-only. For females, lipid levels at emergence were similar to those of females fed a diet supplemented with a ratio of 75:25% honey to olive oil, yet in both of these treatments lipid levels were significantly higher when compared to females fed honey-only. This suggests that females on a lipid-containing diet economized on their lipid use. In contrast, the survival of males and females was negatively affected by the addition of olive oil and no differences in survival were found when wasps were fed 1 day on various ratios of honey to olive oil compared to honey-only. Our results show that the addition of a lipid source can increase or maintain nutrient availability and further research into lipid supplementation could minimize detrimental effects in order to increase the effectiveness of parasitoids in certain agro-ecosystems.     

引进花角蚜小蜂成虫的寿命和羽化节律

通过室内饲养和连续观察,研究了食物、温度对引进花角蚜小蜂成虫寿命的影响及其羽化的时间节律.结果表明：食物对该寄生蜂成虫寿命有极显著影响,喂食20％蜂蜜或20％蜂蜜＋新鲜松针可将雌虫寿命从不喂食的1.5 d延长到14.8 d和17.3 d,将雄虫寿命从不喂食的1.5 d延长到11.3 d和12.3 d.喂食20％蜂蜜条件下,温度也表现出极显著影响,23 ℃和26 ℃下雌、雄成虫的寿命均明显较长,32 ℃下均最短,相同温度下雌虫的寿命显著长于雄虫.日周期中,雌虫主要在11:00-15:00羽化,18:00以后基本不羽化;雄虫主要在9:00-12:00羽化,17:00以后基本不羽化.在花角蚜小蜂的主要羽化期7-9月,7月羽化量最大 ,此后8、9月呈波浪式递减;单日羽化的成虫中,雌虫大多占80％以上,雄虫则长期在一个较低水平波动.对比试验发现,花角蚜小蜂在收蜂棚中的出蜂量比在收蜂箱中更大.花角蚜小蜂在羽化前积累的能量十分有限,人工放蜂前提供必要的营养补充将有助于提高生物防治效果.福建和广东夏季的高温、花角蚜小蜂雌成虫和松突圆蚧雌成蚧虫口高峰期不吻合、极高的雌性比例等是影响该寄生蜂种群稳定的潜在因素.收蜂棚有利于大量收集花角蚜小蜂,适合在生产上应用.     

Does risk of egg parasitism affect choice of oviposition sites by a moth? A field and laboratory study

In many insects the eggs are highly vulnerable and egg parasitism can represent a major cause of mortality. It is thus important for the ovipositing female to find a protected site for her eggs. We have examined how egg parasitation can affect host plant choice by Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae). Ovipositing moths exhibited significantly higher preference for alfalfa compared to cotton, both in the laboratory and the field. However, larval performance, in terms of development rate and the attained larval and pupal weight, was significantly better on cotton than on alfalfa. In laboratory tests no difference in larval survival on the two host plants was observed. To test the hypothesis that seeking enemy-free space could be a factor behind the preference for alfalfa, the parasitation levels on the two plants were investigated. In field tests, the egg parasitoid Chelonus inanitus (Linnaeus) (Hymenoptera: Braconidae) parasitized a significantly higher number of egg batches on cotton than on alfalfa. Furthermore, the parasitoid was significantly faster in finding and parasitizing S. littoralis eggs on cotton than on alfalfa in a cage experiment. These findings support the assumption that the preference for the inferior larval food plant, alfalfa, reflects a search for a host plant species on which attacks by natural enemies are less likely. Possible factors accounting for the preference of S. littoralis for alfalfa and the higher parasitation rates on cotton are discussed.     

Factors influencing parasitism of adult Japanese beetles,Polillia japonica (Col.: Scarabaeidae) by entomopathogenic nematodes

Several factors that influence the activity of steinernematid and heterorhabditid nematodes against adult Japanese beetles were examined in the laboratory. The effect of nematode concentration on mortality of adult beetles was evaluated using a Petri plate bioassay. The adults were exposed to 1,000 to 10,000 infective stage juveniles (J3) ofSteinernema glaseri per 10 beetles with or without food for 24 hr after which they were held with food for an additional 6 days. The LC50s for males with and without food during exposure were 3,435 and 2,854 J3s/10 adults, respectively. The LC50s for mixtures of males and females with and without food were 5,228 and 1,762 J3s/10 adults respectively. Although mortality occurred during and shortly after exposure, significant additional mortality was observed 1–4 days following exposure. Exposure of males and females with food to 10,000 J3s/10 adults for 6, 12, 18 or 24 hr resulted in 47, 58, 72 and 77% mortality, respectively. Comparative activity ofS. glaseri, S. carpocapsae (All strain),S. feltiae (Biosys experimental cold adapted strain=bibionis),S. feltiae (Biosys experimental strain 27),Heterorhabditis bacteriophora, andHeterorhabditis sp. (Terceiran isolate) was evaluated against adult Japanese beetles using a 24 hr exposure to 8,000 J3s/10 adults. The most virulent species wereS. glaseri, S. feltiae (=bibionis), the Terceiran isolate ofHeterorhabditis andS. carpocapsae producing 55, 44, 36 and 34% mortality respectively. Our results indicate that adult Japanese beetles infected with entomopathogenic nematodes could serve as a mechanism for nematode dispersal.     

Is the common sowthistle (Sonchus oleraceus) a primary host plant of the cotton bollworm,Helicoverpa armigera (Lep., Noctuidae)? Oviposition and larval performance

Helicoverpa armigera (Hübner) is a polyphagous pest that has a relatively strong affinity in the field for the European weed Sonchus oleraceus L. in parts of Australia. The oviposition preference of H. armigera was examined in relation to sowthistle and some crop hosts on which it is a pest. In a group test with simultaneous exposure of moths to common sowthistle, maize, sorghum and two cotton cultivars, H. armigera females consistently showed strongest affinities for common sowthistle, irrespective of moth age or the original host of the test insects in the field. Females ( n  = 20) exposed individually to a choice between common sothistle and cotton, varied substantially in preference. Among the females tested, 67% showed a stronger affinity for common sowthistle, about 5% preferred cotton and 28% did not discriminate. Common sowthistle was also the most preferred by newly hatched larvae among the five host plant types presented in a multiple choice test. Larvae fed on common sowthistle flowers had a higher survival rate and body weight than those fed on cotton flowers. These results and previous field observations suggest that S. oleraceus may be a primary host plant (or one of the primary host species) to which H. armigera became adapted at the time of speciation.     

Effect of Dipel (Bacillus thuringiensis) on the survival of immature and adult Hyposoter exiguae (Hymenoptera: Ichneumonidae)

The effects of formulations of Dipel (Bacillus thuringiensis subsp. kurstaki), on immature and adult Hyposoter exiguae (Hymenoptera: Ichneumonidae) were assessed, using Heliothis virescens (Lepidoptera: Noctuidae) as a host. H. exiguae developing in treated hosts had a significantly (p = 0.05) lower percentage of pupation and adult emergence compared to parasitoids developing in nontreated hosts. The mean durations of the pupal and adult stages for parasitoids emerging from treated hosts were not generally affected. After 2 days of exposure, the survival of adult males of H. exiguae fed suspensions containing viable B. thuringiensis spores was significantly lower (p = 0.05) than than the survival of wasps fed either control (sucrose solution), autoclaved Dipel, or inert formulation powder solutions. Survival of H. exiguae fed a low concentration of Dipel was not significantly reduced. Applications of B. thuringiensis in the field would very likely adversely affect immature H. exiguae more than adults, due to premature host death.     

Relative longevity of adult Nezara viridula in field cages of cotton,peanut, and soybean

Producers in the southeastern USA face significant crop losses from the stink bugs Nezara viridula (L.), Euschistus servus (Say), and Chinavia hilaris (Say) (all Hemiptera: Pentatomidae). Cotton, peanut, and soybean are major agronomic crops and host plants of stink bugs in the region. We conducted a field plot study to measure the relative longevity of adult, unmated N. viridula males and females caged on peanut, cotton, and soybean to test three hypotheses: (1) differences in mortality are associated with differences in host plant food suitability, (2) mortality rates increase with age, and (3) males have higher mortality than females. Using survival analysis, we found that the sex of the individual did not affect survival rates on any of the three host plants. Survival was significantly higher in cotton and soybean than in peanut. Mortality rates increased with age in peanut, but not in soybean or cotton. The frequency of canopy temperatures above 35 °C was higher in peanut than in soybean. Peanut appears to be a less than ideal habitat in terms of canopy temperature and/or food quality for N. viridula adults. Both, cotton and soybean were equally suitable food resources for N. viridula adults prior to maturation of the plants.     

Demography of fluctuating prairie vole populations: comparison of demographic variables among phases of fluctuations

We tested for differences in the proportion of reproductively active males and females, proportion of the population composed of young and immigrants, and monthly survival (total, adult, young) among phases (trough, increase, and decline) and among habitats (alfalfa, bluegrass, and tallgrass) of 30 population fluctuations ofMicrotus ochrogaster Wagner, 1842 over 25 years in east-central Illinois USA. Total population survival and survival of adults and young were greatest during the increase phase, among fluctuations, irrespective of habitat. The proportion of reproductively active adult males and females was lowest during the decline phase, an effect of lower reproduction during the winter. These results suggest that phase-specific changes in survival were the primary demographic factor driving population fluctuations ofM. ochrogaster in our study sites. We conclude that small-scale spatially different population fluctuations may be explained by the same mechanisms that explain fluctuations within a population.     

Concurrent modulation of neuronal and behavioural olfactory responses to sex and host plant cues in a male moth

Mating has profound effects on animal physiology and behaviour, not only in females but also in males, which we show here for olfactory responses. In cotton leafworm moths, Spodoptera littoralis, odour-mediated attraction to sex pheromone and plant volatiles are modulated after mating, producing a behavioural response that matches the physiological condition of the male insect. Unmated males are attracted by upwind flight to sex pheromone released by calling females, as well as to volatiles of lilac flowers and green leaves of the host plant cotton, signalling adult food and mating sites, respectively. Mating temporarily abolishes male attraction to females and host plant odour, but does not diminish attraction to flowers. This behavioural modulation is correlated with a response modulation in the olfactory system, as shown by electro-physiological recordings from antennae and by functional imaging of the antennal lobe, using natural odours and synthetic compounds. An effect of mating on the olfactory responses to pheromone and cotton plant volatiles but not to lilac flowers indicates the presence of functionally independent neural circuits within the olfactory system. Our results indicate that these circuits interconnect and weigh perception of social and habitat odour signals to generate appropriate behavioural responses according to mating state.     

Flowers promote ovarian development and vitellogenin gene expression in <Emphasis Type="Italic">Apolygus lucorum</Emphasis> (Heteroptera: Miridae)

Apolygus lucorum (Heteroptera: Miridae), an important herbivore feeding on a broad range of cultivated and wild plants, always shows a strong preference for flowering host plants. In a prior study, we found A. lucorum fecundity to be higher on flowering plants than on plants still at the vegetative stage. This led us to hypothesize that ovarian development and vitellogenin (Vg) expression in A. lucorum, which are highly correlated with its fecundity, might respond positively to the presence of host plant flowers as food. In this study, two types of plant foods, i.e., cotton terminals and flowers, and cotton terminals only without flowers, were examined. Adult females on terminals with flowers had higher ovarian development levels than those of similar stage held on terminals without flowers. Moreover, adults on terminals with flowers had more follicles per ovary throughout adult life than those held on terminals without flowers, and the length of the most developed ovariole of the former treatment was significantly longer than that of the latter diet. Use of qRT-PCR showed that the expression level of Vg was significantly higher in adults raised on a diet with flowers compared with those raised on the diet without flowers. These results suggest that host plant flowers significantly facilitate ovarian development and Vg gene expression of A. lucorum adults.     

Catch-up growth in Japanese quail (Coturnix Japonica): relationships with food intake, metabolic rate and sex

The effects of early environmental conditions can profoundly affect individual development and adult phenotype. In birds, limiting resources can affect growth as nestlings, but also fitness and survival as adults. Following periods of food restriction, individuals may accelerate development, undergoing a period of rapid “catch-up” growth, in an attempt to reach the appropriate size at adulthood. Previous studies of altricial birds have shown that catch-up growth can have negative consequences in adulthood, although this has not been explored in species with different developmental strategies. Here, we investigated the effects of resource limitation and the subsequent period of catch-up growth, on the morphological and metabolic phenotype of adult Japanese quail (Coturnix japonica), a species with a precocial developmental strategy. Because males and females differ in adult body size, we also test whether food restriction had sex-specific effects. Birds that underwent food restriction early in development had muscles of similar size and functional maturity, but lower adult body mass than controls. There was no evidence of sex-specific sensitivity of food restriction on adult body mass; however, there was evidence for body size. Females fed ad lib were larger than males fed ad lib, while females subjected to food restriction were of similar size to males. Adults that had previously experienced food restriction did not have an elevated metabolic rate, suggesting that in contrast to altricial nestlings, there was no metabolic carry-over effect of catch-up growth into adulthood. While Japanese quail can undergo accelerated growth after re-feeding, timing of food restriction may be important to adult size, particularly in females. However, greater developmental flexibility compared to altricial birds may contribute to the lack of metabolic carryover effects at adulthood.     

Pre-release analysis of the overwintering capacity of a classical biological control agent supporting prediction of establishment

This study investigated the effect of temperature on the development and overwintering capacity of the pupal parasitoid, Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae), a candidate classical biological control agent against leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae) in Canada. It was estimated that 256.4 day-degrees, above a lower threshold temperature of 7.3°C, were required for D. pulchellus to complete development, from egg to adult eclosion. Laboratory and field experiments on the immature and mature parasitoids indicated that D. pulchellus overwinters primarily, if not exclusively, in the adult stage. Only adults were able to survive an entire winter under natural outdoor conditions in central Europe. Immature parasitoids developing inside their pupal hosts were capable of withstanding short periods of temperatures as low as −5°C or −10°C, but even much higher temperatures were lethal if sustained for several weeks. Among adults, females demonstrated greater cold hardiness than males. The LTime₅₀ at −12°C, simulating winter temperatures without snow cover, was 4–5 and 6–7 days for males and females, respectively. The LTime₅₀ at −4°C, simulating winter temperatures beneath an insulating snow layer, was 1–2 and 2–3 weeks for males and females, respectively, with maximum survival of eight weeks. It is likely that survival would be even greater in a natural environment where the parasitoids could select optimal overwintering sites and have the option to feed when temperatures rise enough to permit activity. Based on these results, D. pulchellus is expected to survive winters in the targeted release areas of Ontario and Quebec.     

Lifetime gains and patterns of accumulation and mobilization of nutrients in females of the synovigenic parasitoid, Diglyphus isaea Walker (Hymenoptera: Eulophidae), as a function of diet

In nature, adult parasitoids feed to obtain and use nutrients for supplementing and/or replenishing some of their existing array of nutrient reserves. When adults feed on host or non-host food, they can enhance fitness, typically by increasing egg production or longevity. In the present study, ovigeny index (OI) and impact of female fitness, as well as physiological state on the reproductive strategies, were investigated in the synovigenic parasitoid, Diglyphus isaea, fed on host food (2-3rd instars of Liriomyza sativae larvae), non-host foods (10% honey solution) and starved (distilled water, control). The results showed that D. isaea was a strongly synovigenic parasitoid, of which OI value was 0.002. Both types of food enhanced the fecundity and prolonged the longevity of the females. D. isaea females fed on non-host food showed higher levels of gut sugar, body sugar and glycogen than those fed on host food, but the levels of lipid were higher in the host-fed females. D. isaea females seemed to show lipogenesis, with low rates of lipid catabolism sufficient to satisfy the requirement of egg maturation. Females might absorb lipids directly from the haemolymph of paralyzed hosts.     

Effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae), a predator of the cotton leafworm

Abstract:  The effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae) were studied at 25°C, relative humidity of 60 ± 10%, and photoperiod of 14 h light : 10 h dark. Development times of P. nigrispinus nymphs were similar when fed with third or fifth instar larvae of cotton leafworm ( Alabama argillacea Hübner) (Lep., Noctuidae) or Tenebrio molitor L. (Col., Tenebrionidae). When fed with housefly larvae ( Musca domestica L.) (Dipt., Muscidae) or artificial diet, the predator had a longer development time. Independent of diet, instar or sex, the females of P. nigrispinus showed a longer longevity than the males. The total survival of the nymphal stage, on the different diets, varied from 22.46 (fed with housefly) to 77.33% (fed with T. molitor larvae). P. nigrispinus males were heavier when fed with third or fifth instar cotton leafworm larvae than when fed with artificial diet. The weight of the females varied from 37.91 (with artificial diet) to 64.68 mg (with fifth instar cotton leafworm larvae). Independently of the diet, newly emerged females of P. nigrispinus were heavier than the males. Females of P. nigrispinus which were fed with fifth instar cotton leafworm larvae had heavier ovaries than those fed other diets.     

The parasitoids ofSpodoptera littoralis [Lep.: Noctuidae] and their role in population control in Cyprus

This paper is based on 20 months survey and laboratory studies of the parasitoids ofSpodoptera littoralis (Boisduval) (Lep.: Noctuidae) carried out in Cyprus in 1971–72. Regular sampling revealed the presence of 19 further macrolepidopterous members of the ecosystem, includingS. exigua (Hbn.),Heliothis spp. and “Plusia” spp. Attacking these were a complex of at least 37 named primary parasitoids and a single secondary parasitoid. The commonest were the ichneumonidHyposoter didymator (Thnb.) and the braconidsChelonus inanitus (L.),Meteorus unicolor (Wesm.) andMicroplitis rufiventris Kok. and notes on their hosts, hostplants and biology are given. Almost all of the parasitoids were polyphagous and this, together with a wide range of hostplants, appears to improve the carry-over of the parasitoids and permit for greater parasitism of the main pests,S. littoralis andS. exigua. The % parasitism is shown to vary greatly with the situation, being highest in unsprayed lucerne field and unsprayed market gardens, and lowest in potato fields and sprayed vegetable plots. Recommendations are made for possible reductions in crop spraying, permitting the growth of weeds, under certain conditions, mass-rearing and liberation of an endemic parasitoid (C. inanitus) and filling gaps in the parasite complex by the introduction of exotic parasitoids.     

Differential effects of flower feeding in an insect host–parasitoid system

In many insect host–parasitoid systems, both the host and its parasitoids forage on shared floral resources. As a result of insect behaviour, morphology and physiology, flower species may act selectively at different levels of such systems, e.g., between the trophic levels of hosts and parasitoids, between species within a guild, between sexes or individuals within a species or between life history traits within an individual. We asked if effects of selectivity are consistent across levels in the horse chestnut leafminer, Cameraria ohridella, and its parasitoid complex. Insects were exposed singly in no-choice feeding trials to twelve common flower species and their survival and reproduction were recorded. Only one of twelve flower species (Ranunculus acris) tended to selectively favour the longevity of leafminers, but not of parasitoids. No flower species were found to favour parasitoids only. Both trophic levels profited from feeding on Anthriscus sylvestris, however, parasitoids benefited up to eight times more than their hosts. No differences were found among the species of the parasitoid guild, but females lived significantly longer than males, and single individuals within species were able to exploit generally unfavourable flower species. Out of the seven flower species that increased the longevity of leafminer females, only Chaerophyllum hirsutum significantly enhanced the number of eggs laid. Fecundity was generally positively correlated with longevity of leafminer females, but two flower species (C. hirsutum, Taraxacum officinale) had an additional positive effect on fecundity. In conclusion, we demonstrated that flowers act differently on life history traits in a host–parasitoid system at a multitude of biological levels and that these effects are not always consistent across levels. Selective plant-derived resources can therefore modify herbivore–natural enemy interactions in ways that are more complex than currently appreciated.     

Response of adult parasitoids ofBemisia tabaci (Hom.: Aleyrodidae) to leaf residues of selected cotton insecticides

The contact toxicity of eight insecticides to adults of four parasitoids of the sweetpotato whiteflyBemisia tabaci was evaluated in the laboratory. Two common Texas species,Eretmocerus sp. andEncarsia pergandiella Howard, and two exotic species,Eretmocerus mundus Mercet from Spain andEncarsia formosa Gahan from Greece were tested. Insecticides, applied as sprays to greenhouse-grown cotton plants at recommended rates were amitraz (Ovasyn^®), azinphosmethyl (Guthion^®), bifenthrin (Capture^®), buprofezin (Applaud^®), cypermethrin (Ammo^®), methyl parathion and thiodicarb (Larvin^®), with a water control. Parasitoid adults were confined on discs cut from leaves (1) sprayed the same day and (2) sprayed two days previously. Survival in both treatments was measured two and four days following exposure. Significant differences in toxicity were detected among the insecticides. Buprofezin was not toxic to any of the four parasitoids. When caged on leaves sprayed two days previously, only amitraz of the remaining compounds allowed significant general parasitoid survival after two days.E. mundus exhibited the greatest overall tolerance to insecticides, with 40% or more surviving 48 hr after confinement on leaves sprayed with amitraz, thiodicarb and cypermethrin. Survival was generally much reduced after 96 hr. In a separate test, fresh residues of endosulfan (Thiodan^®) were highly toxic at the two rates tested, but two day old residues at the lower rate allowed 76.7% survival ofE. mundus and 35% survival ofE. pergandiella after 48 hrs.     

Effects of transgenic Cry1A＋CpTI cotton and Cry1Ac toxin on the parasitoid, Campoketis chlorideae （Hymenoptera：Ichneumonidae）

Abstract The effect of transgenic double genes, Cry1A + CpTI cotton and Cry1Ac toxin on the parasitoid, Campoketis chlorideae Uchida of cotton bollworm, Helicoverpa armigera (Hübner), was investigated in the laboratory. Helicoverpa armigera larvae when in the first, second and third instar could not survive if fed on transgenic cotton leaves. Consequently, C. chlorideae larvae could not complete their development if parasitizing on such hosts. After H. armigera larvae were reared on transgenic or traditional cotton leaves for 12J48 hours, they were parasitized by C. chlorideae females. Parasitized larvae continued to feed on transgenic or traditional cotton for 12–48 h. The present results showed that the body weight of larvae of the parasitoids were significantly reduced when parasitized hosts fed on transgenic cotton leaves compared to those fed on traditional cotton. Duration of egg and larvae stage were significantly prolonged, pupal and adult weight of C. chloridae was decreased when the host larvae fed on transgenic cotton leaves longer than 48 h. The development duration of C. chlorideae pupae on the hosts fed on transgenic cotton leaves in each treatment was not significantly different from those of controls. The longevity of parasitoid females and males fed with a solution containing Cry1Ac toxin was not significantly different with that of the control.     

Flowers and fruits prolong survival of drosophila pupal parasitoids

Adult parasitoids often feed on sugar sources for survival and to fuel energy. Therefore, the provision of sugar sources, such as nectar from flowers, can enhance biological control. We assessed whether Pachycrepoideus vindemmiae and Trichopria drosophilae, two pupal parasitoids of Drosophila spp., can profit from different sugar sources. In a laboratory experiment, we offered honey, cornflower and buckwheat flowers, crushed and Drosophila suzukii-infested blueberries as well as hosts together with honey. In both parasitoid species, all food sources significantly prolonged the lifespan of females compared to the control. The flowers prolonged the lifespan in both species threefold or fourfold, in P. vindemmiae from a mean of 6 to 28 days, in T. drosophilae from 13 to 49 days. Infested and damaged blueberries also enhanced mean survival in both species. When fed honey, the presence of hosts slightly decreased lifespan in P. vindemmiae and strongly decreased it in T. drosophilae. Our results suggest that the parasitoids can utilize the fruits they encounter during host search. Flowers could enhance their biological control function even further, as long as they do not benefit the pest.