Host Deprivation Research Articles

Evaluation of three cold storage methods of Bagrada hilaris (Hemiptera: Pentatomidae) and the effects of host deprivation for an optimized rearing of the biocontrol candidate Gryon gonikopalense (Hymenoptera: Scelionidae)

The cold storage of host eggs has been utilized in the production of egg parasitoids used in biological control programs. However, similar stockpiling methods can lead to various responses depending on the parasitoid species considered. Hence, standardization of storage methods is difficult. The egg parasitoid Gryon gonikopalense Sharma, is currently being evaluated as a biocontrol agent of Bagrada hilaris (Burmeister), an invasive pest on Brassicaceae crops in the Americas. In this study, we investigated cold storage methods and the effect of host deprivation on G. gonikopalense in order to optimize its rearing process. Laboratory tests were conducted with bagrada bug eggs stored under three temperature treatments (-20 °C, 5 °C, 13 °C) and six durations (one week to three months). In addition, we assessed the effect of host deprivation on parasitoid fecundity and progeny development. Bagrada bug eggs stored at 5 °C up to one month allowed three and nine times more parasitism than eggs stored at 13 and -20 °C respectively. Progeny emergence rate was also the best with eggs stored at 5 °C (94.1%) while eggs stored at 13 and -20 °C led to 77.7 and 89.2 % of emergence respectively. However, the different storage treatments led to similar longevities and body lengths for male and female progeny. In addition, G. gonikopalense did parasitize bagrada eggs after 60 days of host deprivation, but fecundity was reduced by 84%. The results can be used to optimize bagrada bug egg production for use in laboratory and / or field experiments and improve G. gonikopalense rearing and production.

Host Deprivation Effects on the Functional Response and Parasitism Rate of Habrobracon hebetor (Hymenoptera: Braconidae) on Ephestia elutella (Lepidoptera: Pyralidae) in the Laboratory.

Habrobracon hebetor (Say) is an important biological control agent for lepidopteran pests of stored products. In this study, the age-specific functional response, paralysis rate, and parasitism rate of H. hebetor under different host deprivation treatments (PC: without host deprivation, used as the control, P1d: host deprivation, but the host was removed after 1 d contact, and PW: host deprivation from beginning) were evaluated at different larval densities (5, 10, 20, 40, and 80) of the Ephestia elutella (Hübner) at 28 ± 1°C, 75 ± 5% RH and 16:8 h L:D. Ages of parasitoid females used were 2, 5, 10, and 20 d old. The logistic regression results indicated that the functional response of H. hebetor females under different host deprivation treatments was type II. The longest handling time was observed in 20-d old females, while the shortest handling time and highest maximum attack rate (T/Th) were estimated at the age of 2 d in all treatments. The paralysis and parasitism rates of H. hebetor were the highest at 2, 5, and 10-d old in all treatments. The results of this study suggest that H. hebetor females up to 10-d old can be used as an efficient biological control agent against E. elutella. The data of this study can also be used to predict the efficacy of different aged H. hebetor females in controlling E. elutella populations.

Host deprivation effects on population performance and paralysis rates of Habrobracon hebetor (hymenoptera: Braconidae).

Habrobracon hebetor (Hymenoptera: Braconidae) is a gregarious ectoparasitoid that attacks the larvae of several species of pyralid and noctuid moths. The reproduction and population dynamics of parasitoids in general are affected by host deprivation. However, how host deprivation affects H. hebetor is unknown. The effect of host deprivation on the parental generation, life table parameters, and the paralysis rate of the F1 generation of H. hebetor were evaluated using the age-stage, two-sex life table under laboratory conditions. The results indicated that the greatest longevity and the least lifetime fecundity of the F0 generation occurred after 19 days of host deprivation (PW-20 treatment). The life table parameters (intrinsic rate of increase, r; finite rate of increase, λ; and net reproductive rate, R0 ) and the paralysis rate parameters (net paralysis rate, C0 ; transformation rate, Qp ; stable paralysis rate, ψ; and finite paralysis rate, ω) of F1 individuals after PW-20 treatment were significantly higher than those of individuals subjected to the control treatment (no host deprivation). However, no difference was detected between the two host deprivation treatments: host deprivation after 1 day of host contact and immediate host deprivation (PW treatment). Our results demonstrated that the effectiveness of H. hebetor did not decrease even during host deprivation for 19 days. Meanwhile, it was observed that mass rearing of the parasitoid could be improved by providing 10 individuals of 5th instar larvae of Ephestia elutella (Lepidoptera: Pyralidae) with a 20% honey-water solution. © 2020 Society of Chemical Industry.

Effects of Extrinsic, Intraspecific Competition and Host Deprivation on the Biology of Trichopria anastrephae (Hymenoptera: Diapriidae) Reared on Drosophila suzukii (Diptera: Drosophilidae).

The pupal parasitoid Trichopria anastrephae Lima (Hymenoptera: Diapriidae) shows potential to control Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), and understanding the behavior of this parasitoid in challenging environments is important to obtain a higher efficiency in mass rearing and in biological control programs. This study aimed to verify the effects of extrinsic intraspecific competition and the absence of host on the parasitism of T. anastrephae in D. suzukii pupae. Therefore, to evaluate the parasitism of T. anastrephae under intraspecific competition, groups of 20 pupae (24h old) of D. suzukii were offered for different densities of parasitoids (1, 3, 5, or 10 couples) during a 7-day period. Whereas to evaluate the effects of host deprivation on parasitism of T. anastrephae, we tested different treatments: T1-no deprivation, T2-complete deprivation, T3-deprivation every other day, T4-deprivation for 3days, and T5-deprivation for 7days. The increase of density of parasitoids resulted in an increase of oviposition scars on pupae and a longer biological cycle, suggesting the occurrence of superparasitism. Increased density also resulted in a higher percentage of attacked pupae, but did not affect parasitoids emergence nor sex ratio. Host deprivation affected number of parasitized pupae, number and sex ratio of offspring, and the longevity of females. Based on our findings, competition among females do not impair offspring viability, and host deprivation for a period up to 7days do not influence parasitism capacity, indicating that it can be used as a pre-release strategy.

Development and reproduction of the parasitic wasp Allotropa subclavata (Hymenoptera: Platygastridae) on the Japanese mealybug Planococcus kraunhiae (Hemiptera: Pseudococcidae)

Allotropa subclavata Muesebeck (Hymenoptera: Platygasteridae) is one of the most effective natural enemies of the Japanese mealybug Planococcus kraunhiae (Kuwana) (Hemiptera: Pseudococcidae), a serious pest in Japanese orchards. We examined the developmental and reproductive traits including host deprivation effect on oviposition of A. subclavata to evaluate its potential as a biological control agent for P. kraunhiae. The developmental zero and effective accumulative temperature of A. subclavata females and males reared on second-instar nymphs, a suitable host stage for this parasitoid, were 12.3 °C and 514.3 degree days and 12.8 °C and 432.8 degree days, respectively. The longevity of A. subclavata maintained with honey was longer than that of those maintained with water or no feeding. The average numbers of mature eggs in ovaries of the 0- and 30-day-old A. subclavata females were 301.1 and 290.4, respectively, and were not significantly different. Offspring production of 30-day-old A. subclavata females was approximately 80% that of 0-day-old female parasitoids. On average, 50% of all eggs were laid within 24 h of the start of oviposition. The intrinsic rate of increase at 25 °C was 0.115, which is considered to be approximate to that of the host, P. kraunhiae.

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.

Effect of host deprivation on the foraging behavior of the Asian citrus psyllid parasitoid Tamarixia radiata: observations from the laboratory and the field

AbstractThe Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a significant citrus pest and the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) has been released in various citrus‐producing areas in classical biological control programs targeting D. citri. We investigated the effect of host deprivation on the foraging behavior and patch utilization by T. radiata. In the laboratory, females deprived of hosts for 3 days tended to leave patches of 12 nymphs without parasitizing hosts during the ca. 30 min they spent in the patch before leaving. Moreover, half of these females failed to host feed, and those that did host feed, on average, needed more than 15 min to complete feeding. Conversely, non‐host‐deprived females parasitized on average three nymphs before leaving patches without host feeding during the ca. 39 min they spent in the patch. These laboratory observations were compared to mass‐reared female T. radiata that were released onto colonies of D. citri nymphs infesting citrus in the field. Release vials were provisioned with honey and these females had no opportunities to host feed over the 1‐ to 2‐day containment period prior to release. When introduced onto D. citri colonies, 68% T. radiata females abandoned D. citri patches prior to probing hosts, in part, because Argentine ants, Linepithema humile (Mayr) (Hymenoptera: Formicidae), tending colonies disturbed searching parasitoids. These results from laboratory and field studies are discussed in the context of classical biological control, with the aim of understanding how to manipulate host availability and ant activity so establishment rates and impact of T. radiata can be improved.

Pengaruh ketiadaan inang terhadap tanggap reproduksi Trichogrammatoidea armigera Nagaraja dan Trichogramma japonicum Ashmed (Hymenoptera: Trichogrammatoidea) dan implikasinya terhadap penerimaan inang

Trichogrammatoidea armigera and Trichogramma japonicum are polyphagous egg parastioids, that are important as natural enemies. The objective of this research was to study the effect of host deprivation on reproductive capacity of T. armigera and T. japonicum. This study consists of 8 treatments, host deprivation : 0 hour, 1 hour, 2 hours, 3 hours, 6 hours, 12 hours, and 48 hours. Host were replaced every 24 hours. Results showed there are difference with respect of how the two parasitoids respond to the treatment. Deprivation of host for 3 hours in T. armigera resulted in the increase of egg production and parasitism rate. After 12 and 24 hours of not encountering any hosts, the numbers of eggs produced drastically decreased. Treatment on T. japonicum resulted in the reaction of fecundity and parasitism rate overall. Forty eight hours of host deprivation resulted in death of both parasitoids species within 2 days. None of the parasitoids seems to produce any egg.

The influence of feeding and host deprivation on egg load and reproduction of an aphid parasitoid, Aphidius gifuensis (Hymenoptera: Braconidae)

With a view to improving the establishment of Aphidius gifuensis Ashmead, a potential natural enemy for suppression of aphids on vegetables, the effects of host deprivation and honey feeding before release on the parasitoid’s egg load and reproduction were studied under laboratory conditions. Host deprivation significantly affected mummy production and survival rate of female parasitoids. A. gifuensis produced more mummies when exposed to a short period (1 and 2 days) of host deprivation, but when host deprivation lasted for 3 days, their mummy production sharply decreased. Offspring produced by parasitoids that had been deprived of hosts for 2 days were much heavier than those produced by parasitoids deprived of hosts for 1 and 3 days. However, host deprivation did not affect emergence rate or offspring sex ratio; the emergence rate was always above 80%, and the offspring sex ratio was always female biased irrespective of whether the host-deprivation period was 1, 2, or 3 days. Honey feeding greatly increased egg load, longevity and decelerated oosorption of A. gifuensis when hosts were absent, and significantly increased parasitoid mummy production in late age. We discuss the results in the context of augmentative biological control, with the view to understanding how to increase parasitoid performance after they are released.

Tipe peneluran, pengaruh lama ketiadaan inang, dan pakan terhadap keragaan reproduksi parasitoid Anagrus nilaparvatae Pang et Wang (Hymenoptera: Mymaridae)

Anagrus nilaparvatae Pang et Wang (Hymenoptera: Mymaridae) is a major egg parasitoid of brown planthopper, Nilaparvata lugens Stal (Hemiptera: Delphacidae). The purpose of this study was to examine the type of nesting, the effect of host deprivation and feeding on the reproductive performance of parasitoid. Determination of the type of nesting was done by dissecting females of A. nilaparvatae upon emerging. Adult females aged 0, 1, 2, 3, 4, 5, and 6 hours were killed in the freezer. Abdominal of wasp was dissected by micro pin. Mature egg of wasp were calculated and documented. Treatment of host deprivations were conducted by feeding 10% honey solution and depriving female parasitoids of host for 3, 6, 9, 12, and 18 hours consecutively. After treatments, female parasitoids were given hosts every day until the parasitoids died. Another group of parasitoids were given with water and treated with the same lenght of deprivation period. Results showed that the A. nilaparvatae nesting type’s is proovigenic. The egg maturation of parasitoid has been initiated since it first emerge with 75% mature eggs of potential fecundity. In the conditions provided 10% honey solution or water as feed, reproductive performance of A. nilaparvatae decreased with increasing duration of host deprivation period, include realized fecundity, parasitization rate, and longevity of female wasp. The decline in the reproductive performance was done by host deprivation for 9 to 18 hours. Longevity of female wasps varied from one to three days, with higher and lower values consecutively for 9 and 18 hours of host deprivation period.

Fecundity and preferential oviposition by pulse beetle, Callosobruchus maculatus F on chickpea (Cicer arietinum L.) var dollar

In a laboratory experiment female Callosobruchus maculatus distributed eggs on healthy chickpea seeds in a manner that maximizes the amount of resources allocated to each offspring under favourable condition. The female preferred seeds having more quantity of resources to meet the nutrition of her offspring, seeds having healthy seed coat over damaged ones, fresh seeds over infested seeds for laying higher number of eggs under normal day light condition over the total dark. This was more so in presence of multiple copulating males over single one. Host deprivation did not have any influence on fecundity.

Pengaruh lama ketiadaan inang terhadap kapasitas reproduksi parasitoid Snellenius manilae Ashmead (Hymenoptera: Braconidae)

The objective of this research was to study the influence of host deprivation on the oviposition and physiological condition of Snellenius manilae Ashmead. The research was conducted at Laboratory of Bioecology of Parasitoid and Predator, Department of Plant Protection, Faculty of Agriculture, IPB. Ten parasitoids of the same age and cohort were used in this experiment. Deprivation of hosts were done for 1, 2, 3, 4, 5, 6 and 7 days at the beginning and toward the end of their life. All hosts were replaced every 24 hours. Result indicated that host deprivation affects the reproductive capacity of Snellenius manilae. Even though parasitoids were able to lay eggs even when they were deprived of hosts for seven consecutive days, the overall results of host deprivation experiment showed that the length and timing of deprivation period can affect reproductive capacity. Deprivation of hosts tends to increase the parasitism rate and the numbers of eggs laid upon their first encounter of hosts after the treatment. The difference is more pronounced on treatements that allowed parasitism to occur before the deprivation treatment. However, the overall results suggests that deprivation overall decrease the reproductive capacity of the parasitoid. The longevity of deprived individuals was also lengthened. Parasitoids that were given host before deprivation treatments tend to produced more eggs than those were not. These results showed that deprivation of hosts in the field may affect the effectiveness of parasitoids and the success of biological control.

Host testing of the parasitoid Cotesia urabae (Austin & Allen, 1989) (Hymenoptera: Braconidae) to assess the risk posed to the New Zealand nolid moth Celama parvitis (Howes, 1917) (Lepidoptera: Nolidae): do host deprivation and experience influence accept

Retrospective host specificity testing of the recently introduced biological control agent Cotesia urabae Austin & Allen, 1989 against Uraba lugens Walker, 1863 was conducted to assess the potential risk posed to the endemic nolid moth Celama parvitis Howes, 1917. The effect that different periods of host deprivation and prior host exposure (‘experience’) had on the parasitoid's readiness to attack a non-target species was examined in a sequence of consecutive no-choice tests. Even though C. urabae was observed to oviposit on C. parvitis in 91% of the no-choice tests, no parasitoids emerged from the 52% of larvae that survived to complete larval development. Host larvae that died during the laboratory rearing were dissected revealing that 63% contained a parasitoid larva, none of which had developed beyond the second instar within the larvae of C. parvitis. These results show a high level of developmental failure of C. urabae within C. parvitis, confirming that it is not a suitable physiological host. Therefore, potential negative impacts of C. urabae on C. parvitis in the wild are likely to be negligible. Significant differences were found in the attack times between parasitoids with different levels of host deprivation, with younger parasitoids taking longer to initiate attack behaviour. Also, it was observed that the lag until first attack decreased significantly after previous experience with the same host in a succession of no-choice tests. These results suggest that host deprivation and experience may play an important role in increasing the responsiveness to non-target species by C. urabae.

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.

Effects of seasonal variation in host quality and availability on parasitism by the egg parasitoid Telenomus coloradensis

AbstractHemlock looper, Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae), is one of the most important defoliator in North American forests. The common egg parasitoid Telenomus coloradensis Crawford (Hymenoptera: Platygastridae) plays a significant role as a natural control agent, with parasitism levels in spring typically higher than in fall. The objectives of this study were to quantify changes in host acceptance and reproductive performance of the parasitoid in relation to (1) host egg fertilization in fall, (2) host diapause status, (3) host embryonic development in spring, and (4) host deprivation during summer. Our results indicate that T. coloradensis do not have the capacity to develop in unfertilized host eggs, whereas early‐diapausing eggs are more suitable for the parasitoid than post‐diapausing eggs. Furthermore, the host physiological suitability decreases with embryonic development in spring. Finally, a host deprivation period during the summer tends to negatively affect the parasitic activity of T. coloradensis. These laboratory results confirm previous hypotheses concerning T. coloradensis seasonal ecology and contribute to a better understanding of the effect of hemlock looper egg physiology and availability on the reproductive potential of T. coloradensis.

Targeting nutrient retrieval by Francisella tularensis

Targeting nutrient retrieval by Francisella tularensis

Laboratory evaluation of Gryon pennsylvanicum (Ashmead) (Hymenoptera, Platygastridae) as a biological control agent of Leptoglossus occidentalis Heidemann (Heteroptera, Coreidae)

Leptoglossus occidentalis Heidemann (Heteroptera, Coreidae), the western conifer seed bug, is a serious conifer seed pest in North America; after its accidental introduction in Italy, it has spread to several European countries. In Central Italy, severe seed loss was recorded in stone pine forests (Pinus pinea). Classical biological control against L. occidentalis was evaluated by performing laboratory tests on Gryon pennsylvanicum (Ashmead), the most important hymenopteran egg parasitoid of the pest in North America, to acquire biological and demographical parameters. Tests were performed in climatic chambers using glass tubes to house specimens at 26±1°C, 75±5% RH and 16:8 L:D and supplying honey drops as food for adults. G. pennsylvanicum reared on eggs of L. occidentalis has a high fecundity rate (144.55 eggs/female) and 90% of the total number of eggs are laid in the first two weeks of oviposition. Mean oviposition period is 23days. Parasitoid females live a mean of 40days, and longevity is higher in host deprived females. The intrinsic rate of increase (rm) was calculated to be 0.206. Mean sex ratio throughout a female’s life span was 70.42% females, though at the start of oviposition it was over 87% females. Adults survived only four days without honey as food, but up to 50days with food; water did not influence longevity. Females lived significantly longer than males. Fecundity was negatively affected by duration of host deprivation, nevertheless, host-deprived females retained the ability to parasitize host eggs, and without a substantial sex ratio change in offspring. On the whole, G. pennsylvanicum shows potential for use in classical biological control against L. occidentalis. Several factors contribute to its suitability for biological control like high reproductive rate, high sex ratio, long-lived adults, and the ability to maintain reproductive potential during periods of host deprivation with a no substantial change in the sex ratio.

Coping with an unpredictable and stressful environment: The life history and metabolic response to variable food and host availability in a polyphagous tephritid fly

The way energy resources are used under variable environmental conditions lies at the heart of our understanding of resource management and opportunism in many organisms. Here we sought to determine how a time-limited, synovigenic and polyphagous insect with a high reproductive-potential ( Anastrepha ludens), copes behaviourally and metabolically with environmental unpredictability represented by constant and variable regimes of host availability and variation in food quality. We hypothesized that an adaptive response to a windfall of nutritious food would be the rapid accumulation of energy metabolites (whole body lipids, glycogen and proteins) in the female. We also studied patterns of oogenesis as an indicator of egg-reabsorption under stressful environmental conditions. As predicted, patterns of energy metabolites were mainly driven by the quality and temporal pattern of food availability. In contrast, patterns of host availability had a lower impact upon metabolites. When given constant access to high quality nutrients, after an initial increase early in life, whole body lipids and glycogen were regulated downward to a steady-state level and somatic protein levels did not vary. In contrast, when food uncertainty was introduced, whole body lipid, glycogen and protein oscillated sharply with peaks associated with pulses of high-quality food. Production of eggs was highest when offered continuous access to hosts and high quality food. Importantly, females fully recovered their reproductive capacity when fruit became available following a period of host deprivation. With no evidence of egg resorption and high levels of egg dumping, it appears that egg dumping may favour the continuous production of eggs such that the female’s reproductive tissues are ready to respond to rapid changes in the availability of hosts. Our results exemplify the capacity of insects to maximize reproduction under variable and stressful environmental conditions.

Egg-Dumping Behavior is Not Correlated with Wider Host Acceptance in the Seed Beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae)

Abstract If typical host plants are absent, some herbivorous insects “dump” eggs on unsuitable substrates, even though this can cause complete larval mortality and reduced maternal life span. In the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae: Bruchinae), the tendency to dump eggs varies genetically both within and between populations. A previous study hypothesized that egg-dumping behavior facilitates host-range expansions, and suggested that such expansions have served to maintain “dumper” genotypes in beetle populations. We tested this hypothesis in two experiments. For both African and Asian beetle populations, full-sib females from >60 families were split among three treatments: no seeds, a less-preferred novel host, and a preferred host. Within each population, we found no correlation among families between the tendency to dump eggs and the tendency to accept the novel host. We also compared egg dumping between selection lines that had adapted to a novel host and a line that had remained on the ancestral host. Females from lines that had evolved greater acceptance of the novel host did not dump more eggs if hosts were absent. Thus, neither experiment supported the host-range expansion hypothesis. Egg distributions on the preferred host in the first experiment provided weak support for a more proximate explanation: family-level variation in the tendency to dump eggs is inversely related to the tendency to avoid superparasitism of seeds. Such a relationship is also evident in comparisons between populations. Given the considerable short-term costs of egg dumping, we suggest that the host-range expansion hypothesis requires unrealistically high frequencies of host deprivation and subsequent host shifts in C. maculatus.

Oviposition behavior of wild Zabrotes subfasciatus (Coleoptera, Chrysomelidae) females deprived of the host Phaseolus vulgaris (Fabaceae)

The insects oviposition behavior is fundamental to study population dynamics, life history evolution, insect-plant and parasitoid-host interactions. Zabrotes subfasciatus (Boheman, 1833) females oviposition behavior in the presence and absence of a host is unknown. The main objective of this study was to describe in detail the oviposition behavior of host deprived or non-deprived females, and observe how the several situations of deprivation (days without host) influence oviposition. Six groups were assembled, three deprived of the host (for 2, 5 and 8 days) and three control groups (with host), each containing one newly-emerged couple (0-24h) of wild Z. subfasciatus, The non-deprived (control) groups received the hosts every day (5 bean seeds Phaseolus vulgaris (Fabaceae)) and the others were deprived for 2, 5 and 8 days, respectively. For each group 12 repetitions were made. Consequently, 12 couples were host deprived during two days, 12 couples were host deprived during five days and 12 couples were host deprived during eight days. When the seeds of the deprived groups were added the experiments started. There was a control group for each deprived group. The experiments and the insects were maintained at constant temperature 29 ± 2ºC and 70-80% relative humidity. At 15 minutes interval, the number of times the females manifested the different categories of behavior was observed (frequency). The behavior categories were: rest inside the box, locomotion, resource exploration (seeds), copulation and oviposition. The deprived females stayed most of the time in contact with the host to carry out oviposition, while the non-deprived (control) females spent most of the time at rest. This was observed in all the deprivation times. The results show that host deprivation influences the oviposition behavior of the studied species and also shows the flexibility in the oviposition strategies that these females present when the environment changes (absence and presence of resources)