Influence of floral resources on sugar feeding and nutrient dynamics of a parasitoid in the field

Abstract.  1. To investigate how floral resources impact feeding and nutrient dynamics of parasitoids, the ichneumonid Diadegma insulare (Cresson) was monitored in cabbage fields with and without buckwheat Fagopyrum esculentum Moench borders. Biochemical analyses of field-collected wasps determined whether sugar feeding occurred, and whether it enhanced nutrient levels and increased parasitism of diamondback larvae Plutella xylostella (L.) from 2000 to 2003. The effects of experimental spatial scale on sugar feeding dynamics were also evaluated in 2001.
2. The majority of D. insulare foraging on cabbage had fed upon sugar, but floral borders did not consistently increase the proportion of sugar-fed wasps or their levels of glycogen and lipid over all 4 years. Floral borders increased sugar storage by females in 2001. More females fed on sugar when experimental plots were separated by at least 800 m compared with 67 m.
3. Feeding on buckwheat nectar vs. honeydew produced by the soybean aphid Aphis glycines Matsumura in surrounding fields was distinguished using the ratio of fructose to total sugars, which was higher in nectar- than in honeydew-fed parasitoids. Floral borders increased the probability that females collected from adjacent crops were nectar-fed in 2002, demonstrating that floral resources were utilised by foraging parasitoids. Diadegma insulare that fed upon any sugar source had higher levels of sugar and glycogen than unfed wasps, and feeding on honeydew appeared to enhance nutrient storage.
4. The prevalence of sugar or nectar feeding by female D. insulare was not correlated with parasitism rates over the 4 years from all plots, but nectar feeding was positively correlated with parasitism rates within floral plots.     

Impact of flowering buckwheat on Lepidopteran cabbage pests and their parasitoids at two spatial scales

We assessed the potential of annual buckwheat, Fagopyrum esculentum Moench, to lead to improved parasitism of lepidopteran cabbage pests over four years. Pest, parasitism, and hyperparasitism rates were monitored in replicated cabbage plots (12 × 20 m) with or without 3 m wide buckwheat borders from 2000 to 2003. Floral borders did not significantly increase egg, larval, or pupal densities of cabbage looper, Trichoplusia ni (Hübner), imported cabbageworm, Pieris rapae (L.), or diamondback moth, Plutella xylostella (L.). Buckwheat increased parasitism rates by Voria ruralis (Fallen) on T. ni larvae and Cotesia rubecula (Marshall) on P. rapaelarvae over four years. Parasitism by Diadegma insulare (Cresson) on P. xylostella larvae was higher in buckwheat than control plots in the first year, and parasitism by Euplectrus plathypenae (Howard) on T. ni larvae was lower in buckwheat than control plots in the second year. The hyperparasitoid Conura side (Walker) attacked D. insulare all four years, but buckwheat did not affect hyperparasitism rates. The effect of spatial scale on pest densities and parasitism in 2001 was evaluated by comparing plots separated at least 67 m (nearby) versus 800 m apart (isolated). T. ni pupae and P. rapae eggs and pupae were more abundant in plots in closer proximity, whereas P. xylostella densities did not vary by the spatial separation of plots. Tachinids and Pteromalus puparum (L.) attacked more P. rapae in nearby plots. E. plathypenae responded to the treatment × scale interaction, parasitizing more in control than buckwheat when plots were isolated but not when plots were nearby.     

Life history of Aptesis nigrocincta (Hymenoptera: Ichneumonidae) a cocoon parasitoid of the apple sawfly, Hoplocampa testudinea (Hymenoptera: Tenthredinidae)

Aptesis nigrocincta: Gravenhorst is a bivoltine ectoparasitoid of apple sawfly cocoons, hosts that must be found and parasitized by females at a depth of 10-25 cm in the soil. Females are significantly smaller than males and nearly wingless. After encountering a host, females needed 29.3 min at 20 degrees C and 19. 9 min at 25 degrees C to deposit an egg on the host. Development from egg to adult took 39.6 days for females and 38.0 days for males at 20 degrees C. This small difference was significant. At 20 degrees C, the longevity of females that had no opportunity to oviposit was on average 72.5 days, significantly higher than male longevity (50.6 days). The longevity of females given access to hosts throughout their lifetime averaged 58.6 days. Females were able to mate immediately after emergence and copulation lasted on average 21.7 s. After a pre-oviposition period averaging 5.8 days, females laid 20.2 eggs during their lifetime, thus less than one egg per day. Neither the fecundity nor longevity of individual females was correlated with body size. If females were deprived of food, longevity as well as lifetime fecundity were drastically reduced. Field studies were carried out in one organically managed apple orchard in Switzerland. Aptesis nigrocincta showed parasitism rates ranging from 12.1 to 39.7 % within single parasitoid generations, thereby constituting the most important mortality factor of apple sawfly cocoons.     

The effect of male mating history on paternal investment, fecundity and female remating in the seed beetle Callosobruchus maculatus

1. In many organisms, males provide nutrients to females via ejaculates that can influence female fecundity, longevity and mating behaviour. The effect of male mating history on male ejaculate size, female fecundity, female longevity and female remating behaviour in the seed beetle Callosobruchus maculatus was determined.
2. The quantity of ejaculate passed to females declined dramatically with successive matings. Despite the decline, a male's ability to fertilize a female fully did not appear to decline substantially until his fourth mating.
3. When females multiply mated with males of a particular mated status, the pattern of egg production was cyclic, with egg production increasing after mating. Females multiply mated to virgins had higher fecundity than females mated to non-virgins, and females mated to twice-mated males had disproportionately increased egg production late in their life.
4. Females that mated to multiple virgins, and consequently laid more eggs, experienced greater mortality than females mated only once or mated to non-virgins, suggesting that egg production is costly, and rather than ameliorating these costs, male ejaculates may increase them by allowing or stimulating females to lay more eggs.
5. Females mating with non-virgin males remated more readily than did females mated to virgins. Females given food supplements were less likely to remate than females that were nutritionally stressed, suggesting that females remate in part to obtain additional nutrients.     

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.     

成虫取食对棉铃虫雌蛾繁殖的影响

试验对雌蛾设置５个食物处理,定量地研究了成虫取食对棉铃虫蛾繁殖和寿命的影响,成虫取食对雌蛾与寿命和主效量均显著影响,补充营养延长雌蛾寿命,提高产卵量,并且」补充营养对产卵量的影响比其对寿命的影响更大,分析表明被营养的作用在于提高雌蛾后期的存活率和产卵量,前期补充营养比后期补充营养具有更大的作用。雌雌全重及其蝮部干重受成廊和的自龄的双重影响,补充营养时雌蛾体重、腹部干重及其脂肪含量下降慢,补充营养可     

The effect of body size on oviposition success of a minute parasitoid in nature

1. Individual fitness is often assumed to be positively correlated with body size, but this has rarely been explored under realistic field conditions. This assumption was tested in a minute parasitoid foraging for planthopper eggs in saltmarsh habitats. 2. We used a novel sampling technique that captures females as they naturally die and fall off the vegetation, and estimated their oviposition success according to the number of eggs remaining in their bodies. 3. Our results support a positive relationship between oviposition success and body size of female parasitoids. 4. Only a single female had exhausted her eggs before she died suggesting that the larger body size advantage is not realised primarily via increased fecundity, but instead via increased longevity or foraging‐efficiency.     

Lifetime gains of host-feeding in a synovigenic parasitic wasp

Abstract. Understanding behavioural decisions relative to host use for feeding or reproduction by foraging parasitoids requires not only the study of metabolic pathways followed by nutrients, but also the quantification of lifetime fitness gains of each alternative behaviour. By using a combination of observational and manipulative approaches, the lifetime host‐feeding gains are measured both in terms of fecundity and longevity in the parasitoid Eupelmus vuilletti. Host‐feeding increases both egg production and longevity. The increase in fecundity is mainly determined by the amount of lipids obtained whereas the lifespan extension is mainly determined by carbohydrates. Proteins obtained through host‐feeding have been implicated previously in egg production by parasitoids but protein intake has no effect on fecundity and longevity in E. vuilletti. The amount of nutrients gained through host‐feeding and invested in eggs is variable and changes over the lifetime of the animal. Therefore, lifetime feeding gains are best understood through the construction of dynamical budgets running over the entire lifespan of an insect.     

Comparison of Diadegma insulare (Hymenoptera: Ichneumonidae) and Microplitis plutellae (Hymenoptera: Braconidae) as biological control agents of Plutella xylostella (Lepidoptera: Plutellidae): field parasitism, insecticide susceptibility, and host-searching

Parasitism of Plutella xylostella (L.) third and fourth instars was evaluated in a cabbage field in Geneva, NY, in 1999. Over the entire season, average parasitism was 33.6% for third instars and 53.6% for fourth instars, and the main parasitoids were Diadegma insulare (Cresson) and Microplitis plutellae Muesbeck. In the early season, total parasitism was low, and mainly caused by D. insulare. However, later in the season, parasitism reached >80% for the fouth instars and 50% for the third instars. Our survey indicated that M. plutellae heavily parasitized P. xylostella, and provided higher parasitism rates than D. insulare in the late season. Comparison of these two species in laboratory bioassays indicated there were no significant differences in susceptibility to four insecticides commonly used in crucifer fields. For both parasitoids, an experience with P. xylostella on a damaged leaf increased their host-searching efficacy. Compared with M. plutellae, D. insulare was a better host-searcher both for the naive and the experienced adults. Although both parasitoids can cause high mortality rates of P. xylostella, D. insulare may be more suitable to be released in fields to enhance natural control against P. xylostella.     

Increasing vineyard floral resources may not enhance localised biological control of the leafroller Epiphyas postvittana (Lepidoptera: Tortricidae) by Dolichogenidea spp. (Hymenoptera: Braconidae) parasitoids

In agroecosystems, the efficacy of biological control exerted by many parasitoids is predicted to be enhanced where the availability of floral resources is increased. Such resources may attract parasitoids and enhance their longevity and fecundity. In Hawke's Bay, New Zealand, this prediction was tested by adding varying quantities of potted flowering alyssum (Lobularia maritima) (Brassicaceae) to plots containing apple plants (Malus domestica) inoculated with larvae of the leafroller, Epiphyas postvittana (Lepidoptera: Tortricidae). In two replicated trials, over 90% of the parasitoids from recovered larvae were Dolichogenidea spp. (Hymenoptera: Braconidae). In both trials increasing the percentage of alyssum did not result in a corresponding increase in the leafroller parasitism rate. Instead, the primary influence on parasitism rates was due to Dolichogenidea spp. dispersing from a nearby orchard. A significant negative correlation was observed in leafroller parasitism as a function of distance from this orchard. A vineyard to the north of the study site also influenced parasitism rates. Our results suggest the orchard was a regional source population for this parasitoid, and the abundance of local resources such as alyssum did not influence parasitoid foraging. At the level of our entire study block, our effective area of resource provision was 0.1%. A level of resource provision higher than that used in this study may be necessary to test for a positive influence on local parasitism rates. From our results, it appears that for parasitoids with relatively high dispersal rates, the availability of local resources may not be as important as a regional source population.     

Body size as an indicator of parasitoid quality in male and female Anagyrus kamali (Hymenoptera: Encyrtidae)

The parasitoid Anagyrus kamali Moursi was recently introduced into the Caribbean as a biological control agent against the hibiscus mealybug, Maconellicoccus hirsutus Green. In the laboratory, parasitoid size, as measured by left hind tibia length, was positively correlated with several indicators of the parasitoid's fitness: longevity, mating preference, fecundity, reproductive longevity, progeny emergence and sex-ratio. When fed ad libidum with honey drops, large male parasitoids lived significantly longer (29.1 +/- 6.5 days) than small ones (18.4 +/- 5.7 days). Large females also lived significantly longer (35.4 +/- 10 days) than small females (27.9 +/- 9.6 days). Females showed no significant mating preference between large and small males. Lifetime fecundity was positively correlated with the size of adult females and ranged from 37 +/- 21 eggs for small females to 96 +/- 43 eggs for large ones. The reproductive longevity, daily oviposition rate, and number of progeny were also higher among large parasitoids. The sex ratio of progeny from small female parasitoids was higher (0.76 +/- 0.24) than that of large individuals (0.47 +/- 0.18).     

Comparing floral nectar and aphid honeydew diets on the longevity and nutrient levels of a parasitoid wasp

We compared the effects of floral nectar from buckwheat, Fagopyrum esculentum Moench, and honeydew produced by the soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae), on longevity, nutrient levels, and egg loads of the parasitoid Diadegma insulare Cresson (Hymenoptera: Ichneumonidae). Diadegma insulare lived for 2 days in control treatments of water or clean soybean leaves, for 6–7 days with honeydew, and in excess of 2 weeks with buckwheat nectar. Potential reasons for the superiority of buckwheat nectar over soybean aphid honeydew for extending the longevity of parasitoids include: (i) parasitoids ingest more sugars from floral sources, (ii) oligosaccharides in honeydew have a lower nutritional value than nectar sugars, and (iii) honeydew has antagonistic compounds. Overall sugar levels were lower in honeydew‐ vs. nectar‐fed female wasps, suggesting a lower feeding rate, but other explanations cannot be excluded. Diadegma insulare eclosed with high levels of lipids and glycogen, and low levels of gut and storage sugars. All carbohydrates increased over the life of both nectar‐ and honeydew‐fed wasps, but remained low or decreased in starved wasps. Lipid levels declined over the lifespan of female wasps, but females fed floral nectar showed the slowest rate of lipid decline. Diet did not affect egg load, probably because the females were not given hosts in the experiment.     

Effect of host feeding on life history traits of <Emphasis Type="Italic">Tamarixia radiata</Emphasis>, parasitoid of the Asian citrus psyllid, <Emphasis Type="Italic">Diaphorina citri</Emphasis>

The parasitoid Tamarixia radiata (Hymenoptera: Eulophidae) is being used for the biological control of the Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Liviidae). The parasitoid is strongly synovigenic, as it is born with very few mature eggs. Synovigenic insects need to feed on host haemolymph to mature additional eggs, and are able to resorb mature eggs to allocate resources toward maintenance. We investigated the effect of host feeding on parasitism, longevity and egg load dynamics, and estimated egg maturation and resorption rates. Although host feeding does not increase survival or longevity, it results in increased parasitization rates when parasitoids are seven days old, and that a single host meal leads to an average gain of three eggs. We discuss the importance of these data to predict the foraging and parasitization behavior of T. radiata in the field, and to potentially improve current efforts to control ACP.     

Effects of buckwheat flowers on leafroller (Lepidoptera: Tortricidae) parasitoids in a New Zealand vineyard

Abstract 1 The provision of floral resources in agricultural ecosystems can potentially enhance biological control of pests by providing nutrients to parasitoids. To test this, the effect of buckwheat Fagopyrum esculentum Moench flowers on leafroller parasitoids was investigated in a New Zealand vineyard. 2 Relative abundance of parasitoids was assessed with yellow sticky traps in buckwheat and control plots. Male Dolichogenidea tasmanica (Cameron) (Hymenoptera: Braconidae) were significantly more abundant in the presence of buckwheat. No significant result was found for female D. tasmanica or either sex of Glyptapanteles demeter (Wilkinson) (Hymenoptera: Braconidae), the other leafroller parasitoid caught. 3 The relative parasitism rate of leafrollers by D. tasmanica was assessed with a leafroller release and recover technique. No difference in parasitism was found between buckwheat and control plots. 4 The sex ratio (% males) of D. tasmanica emerging from recovered leafroller larvae was significantly lower in the presence of buckwheat than in control plots on one of the two release dates. Possible reasons for this increase in female production are discussed.     

Egg-laying tactic in Phyllomorpha laciniata in the presence of parasitoids

Female insects are expected to choose oviposition sites that have the best conditions for offspring development and survival. Natural enemies, such as predators and parasitoids, may have a strong influence on the selection of oviposition substrates by phytophagous insects. The golden egg bug, Phyllomorpha laciniata (Villers) (Heteroptera: Coreidae) has an unusual reproductive strategy. Females mainly use conspecifics, both males and other females, as egg-laying substrates, but occasionally they oviposit on plants as well. Survival of the eggs is higher when eggs are carried by conspecifics than when they are laid on plants, due to predation and parasitism. We investigated egg-laying behavior in the forced presence of the egg parasitoid Gryon bolivari (Giard) (Hymenoptera: Scelionidae). Specifically, we studied whether females provide egg protection by avoiding oviposition under the risk of egg parasitization. We expected a lower oviposition rate under parasitoid presence, and the eggs, if any, to be placed preferably on conspecifics and not on plants, thus ensuring higher survival of the progeny. The results show that P. laciniata 's egg-laying rate was lower when they were enclosed with parasitoids than when parasitoids were absent, especially when plants were the only substrate to oviposit on. Moreover, females showed strong preference for laying eggs on conspecifics rather than on plants. Egg-laying in P. laciniata appears to be not only influenced by the availability of conspecifics, but also by the presence of egg parasitoids. This indicates that females may be able to detect G. bolivari and avoid oviposition when parasitoids are present. We discuss the possibility of conspecifics as enemy-free space.     

Intraspecific variability in egg maturation patterns and associated life‐history trade‐offs in a polyembryonic parasitoid wasp

1. Life‐history theory predicts a trade‐off between the resources allocated to reproduction and those allocated to survival. Early maturation of eggs (pro‐ovigeny) is correlated with small body size and low adult longevity in interspecific comparisons among parasitoids, demonstrating this trade‐off. The handful of studies that have tested for similar correlations within species produced conflicting results. 2. Egg maturation patterns and related life‐history traits were studied in the polyembryonic parasitoid wasp, Copidosoma koehleri (Hymenoptera: Encyrtidae). Although the genus Copidosoma was previously reported to be fully pro‐ovigenic, mean egg loads of host‐deprived females almost doubled within their first 6 days of adulthood. 3. The initial egg‐loads of newly emerged females were determined and age‐specific realised fecundity curves were constructed for their clone‐mate twins. The females' initial egg loads increased with body size, but neither body size nor initial egg load was correlated with longevity and fecundity. 4. The variation in initial egg loads was lowest among clone‐mates, intermediate among non‐clone sisters and highest among non‐sister females. The within‐clone variability indicates environmental influences on egg maturation, while the between‐clone variation may be genetically based. 5. Ovaries of host‐deprived females contained fewer eggs at death (at ～29 days) than on day 6. Their egg loads at death were negatively correlated with life span, consistent with reduced egg production and/or egg resorption. Host deprivation prolonged the wasps' life span, suggesting a survival cost to egg maturation and oviposition. 6. It is concluded that adult fecundity and longevity were not traded off with pre‐adult egg maturation.     

Egg and time limitation mediate an egg protection strategy

The number of mature eggs remaining in the ovaries and the time left for oviposition determine the reproductive decisions of the hyperdiverse guild of insects that require discrete and potentially limiting resources for oviposition (such as seeds, fruits or other insects). A female may run out of eggs before all available oviposition sites are used (egg limitation), or die before using all of her eggs (time limitation). Females are predicted to change clutch size depending on whether eggs or time is the limiting resource. We extend this framework and ask whether the same constraints influence a strategy in which females modify eggs into protective shields. In response to egg parasitism cues, female seed beetles (Mimosestes amicus) lay eggs in vertical groups of 2–4, modifying the top 1–3 eggs into shields in order to protect the bottom egg from attack by parasitoids. We made contrasting predictions of how egg and time limitation would influence egg size and the incidence and level of egg protection. By varying access to seed pods, we manipulated the number of remaining eggs a female had at the time she received a parasitism cue. Although egg size was not affected, our results confirm that egg‐limited females protected fewer eggs and time‐limited females protected more eggs. Female body size explained the number of eggs in a stack rather than host deprivation or the timing of parasitoid exposure. Our results clearly show that host availability relative to female age influences the incidence of egg protection in M. amicus. Furthermore, our study represents a novel use of life history theory to explain patterns in an unusual but compelling defensive behaviour.     

Food availability affects<Emphasis Type="Italic"> Osmia pumila</Emphasis> (Hymenoptera: Megachilidae) foraging,reproduction, and brood parasitism

Food limitation can reduce reproductive success directly, as well as indirectly, if foraging imposes a risk of predation or parasitism. The solitary bee Osmia pumila suffers brood parasitism by the cleptoparasitic wasp Sapyga centrata, which enters the host nest to oviposit while the female bee is away. I studied foraging and reproduction of O. pumila nesting within cages stocked with rich or sparse floral resources, and the presence or absence of S. centrata to test (1) the response of nesting female O. pumila to food shortages, (2) the response of nesting female O. pumila to the presence of parasites, and (3) whether brood produced under scarce resources are more likely to be parasitized by S. centrata. The rate of brood cell production was significantly lower in cages with sparse floral resources, although females in sparse cages did not produce significantly fewer brood cells overall. Sapyga centrata did not influence the rate of brood cell production, but females exposed to the cleptoparasites had marginally significantly lower reproductive output. Nests in parasite cages had significantly fewer brood cells than those in parasite free cages. The mean duration of foraging bouts made by female O. pumila in sparse cages was not significantly longer than that in rich cages. O. pumila spent less time in the nest between pollen and nectar foraging bouts in sparse cages with S. centrata than those in other cages suggesting that these individuals made more frequent food foraging trips. Despite the weak effects of parasites and bloom density on foraging behavior, O. pumila brood cells experienced a 5-fold higher probability of parasitism by S. centrata in cages with sparse bloom than in those with rich bloom [corrected]. These results support the hypothesis that indirect effects of food scarcity increase O. pumila susceptibility to brood parasitism, although the exact mechanism is not entirely clear yet.     

Herbivore response to habitat manipulation with floral resources: a study of the cabbage root fly

Biological control of pest insects can be improved by providing natural enemies with additional food resources such as floral nectar within the production field. However, herbivores may also benefit from this practice. The aim of this 3‐year field study was to investigate if dill and buckwheat, aimed as food resources for natural enemies, could increase the densities of the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae), a severe pest on crucifers. Differences in egg density, numbers of pupae and sex ratio were compared between cabbage plots with or without flowers. Habitat manipulation by intercropping flowering plants with cabbage did not increase the overall D. radicum egg density in our 3‐year study, and there were no significant differences in egg numbers between treatments in any year. No effect on the fecundity of D. radicum was observed, most likely because of the high mobility and feeding behaviour of the female flies, combined with high abundance and diversity of other food sources around the fields during this period. Despite equal egg numbers, fewer pupae were found in plots with flowers than without in one of three studied years. This finding suggests that natural enemies attacking larvae and pupae of D. radicum were either more abundant or efficient in cabbage plots with flowers.     

Costs and benefits of host feeding in the parasitoid wasp Trichogramma turkestanica

Females of the parasitoid wasp Trichogramma turkestanica Meyer (Hymenoptera: Trichogrammatidae) generally host feed after ovipositing on the first egg of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) they encounter. We measured the impact of host feeding on the fecundity and longevity of females, in absence of host or food, and on the fitness of their progeny. We also determined if the frequency of host feeding is influenced by the humidity level at which T. turkestanica females developed. Host feeding increased egg production by 70% but decreased female longevity. This impact of host feeding on the longevity of females is probably due to the allocation of carbohydrates to egg production at the expense of somatic maintenance. Humidity did not influence the occurrence or duration of host feeding. The size of individuals developing in eggs on which females host fed was smaller, indicating that their fitness was affected.