The function of host discrimination and superparasitization in parasitoids (original) (raw)
Related papers
Avoidance of superparasitism: a matter of learning?
Animal Behaviour, 1999
Superparasitism (laying eggs into parasitized hosts) by solitary parasitoids was regarded for a long time as a mistake on the part of the foraging parasitoid, but is now widely accepted as often adaptive. In Venturia canescens the rate of avoidance of superparasitism has been shown to rise over the first 20 min from the deposition of the first egg, possibly because of a constraint in the detectability of the marker used to label parasitized hosts. Here, we show that the increase in avoidance of superparasitism with time is the result of a female's experience of hosts in the interval between laying an egg in a host and re-encountering that same host. Wasps deprived of hosts in this interval showed no avoidance of superparasitism; those given healthy hosts every 3 min during this interval showed increasing avoidance of superparasitism with time. Furthermore, the marker was detectable in a host within 3 min of oviposition. The results suggest that wasps quickly acquire information about the abundance of healthy hosts in their environment, and base their decision to superparasitize on this information.
Parasitoids flip a coin before deciding to superparasitize
Journal of Animal Ecology, 2004
Host acceptance decision in parasitic wasps depends strongly on the parasitism status of the encountered host. In solitary species, a host allows the development of only a single parasitic larva, and then any oviposition in an already parasitized host leads to larval competition and to potential loss of offspring. The ability of parasitoids to discriminate between parasitized and healthy hosts is well documented. Despite this, parasitized hosts are still accepted by the foraging wasps, an occurrence termed superparasitism.
Population Ecology, 1986
During the summer of 1969-70, the New Zealand Department of Scientific and Industrial Research released four species ofparasiticwasps (Hymenoptera: Chalcidoidea) at selected sites throughout New Zealand to assist in the biological control of the house fly, Musca domestica L, and other flies associated with man. The species were Muscidifurax zaraptor KOOAN and LEONER, M. uniraptor K & L, Pachycrepoideus vindemiae RONDANI, and Spalangia endius WALKER. The native hosts and the geographic distribution of these species are described by BOUCEK (1963), LEGNER and BRYDON (1966), LEONER and OLTON (1968), and CUMBER (1969). Experiments, including a study of egg-laying behaviour, were undertaken by the second author to determine population growth potential of the parasites under controlled physical conditions. As an aid to interpreting experimental results we exploit a group of probability models whose use for describing the avoidance ofsuperparasitism is proposed in DALEY and MAINDONALD (1982). These models have the merit that their form can be varied to investigate alternative biological mechanisms. Problems in handling the estimation for one of these models lead us to use, in one instance, the closely equivalent model which is an extension of GRIFFITHS (1977a, 1977b). "Superparasitism", as used in this paper, refers to the laying of more than one egg on a house fly pupa (WYLIE, 1965). METHODS AND MATERIALS In the first group of experiments ('uncrowded conditions') a solitary female was placed in a vial with 5, 15, or 30 host pupae. Twenty replicates were in each instance taken. In a second series of experiments 10 females were placed, under deliberately more crowded conditions, with 50 hosts. Ten replicates were taken in each instance. Except for the uniparental species M. uniraptor an equal number of male parasites was always included. Conditions were maintained at 26-4-1.5~ 60% RH and 12-h photoperiod.
Impact of mating status on egg-laying and superparasitism behaviour in a parasitoid wasp
Entomologia Experimentalis et Applicata, 2007
Most parasitoid female wasps can distinguish between unparasitized and parasitized hosts and use this information to optimize their progeny and sex allocation. In this study, we explored the impact of mating on oviposition behaviour (parasitism and self-and conspecific superparasitism) on both unparasitized and already parasitized hosts in the solitary parasitoid wasp Eupelmus vuilleti (Crw.) (Hymenoptera: Eupelmidae). Virgin and mated females had the same oviposition behaviour and laid eggs preferentially on unparasitized hosts. The sex ratio (as the proportion of females) of eggs laid by mated females in parasitism and conspecific superparasitism was 0.67 ± 0.04 and 0.57 ± 0.09, respectively. Likewise, females laid more eggs in conspecific superparasitism than self-superparasitism under our experimental conditions. These experiments demonstrate that E. vuilleti females can (i) discriminate between unparasitized and parasitized hosts and adapt the number of eggs they lay accordingly, and (ii) probably discriminate self from conspecific superparasitized hosts. Finally, mating does not appear to influence the host discrimination capacity, the ovarian function, or the oviposition behaviour.
Evolutionary Ecology, 1992
Many parasitoids superparasitize, in which an insect attacks a previously parasitized host, laying an egg in the host even though only one offspring will emerge from the host. In this paper superparasitism is considered from the perspectives of optimal foraging theory, evolutionarily stable strategies, and quantitative genetics. The focal question is: at what point in its life should an individual parasitoid begin attacking previously parasitized hosts? Each of the three theoretical methods can be used to answer the question and by doing so, we see how the three methods are connected. Qualitative, empirical predictions based on the theories are described.
Repeated probing of hosts: an important component of superparasitism
Behavioral Ecology, 2012
Parasitoids that encounter a previously parasitized host inspect it externally and internally, sometimes eventually laying additional eggs (superparasitism). The fitness effects of increased clutch sizes generated through superparasitism are widely studied, whereas the consequences of multiple host probings during the inspection received less attention. To address this issue, we offered a host to 1-5 females of the encyrtid wasp Copidosoma koehleri consecutively, or presented it 1-5 times to a single female. We noted whether the hosts died before pupation of either host or wasp, produced parasitoid pupae, or developed into moth pupae. Additional hosts were dissected after varying numbers of probings to determine their parasitoid egg loads. Host rejection rates prior to ovipositor insertion did not differ between treatments. Host rejections after ovipositor insertion, characterized by brief (<10 s) probing durations, were more common in the single-than in the multiple-female treatment. This could reflect avoidance of self-superparasitism, or increased selectivity by host-experienced females. Egg number per host increased with the number of prolonged probings in both treatments. Some hosts that received 1-2 probings (brief or prolonged) yielded moth pupae, while no hosts with five probings survived to pupation. Hosts probed three times (corresponding to <1 and 2.2 eggs in the single-and multiple-female treatments, respectively) produced the largest proportion of parasitoid pupae. The parasitoids' success is thus strongly affected by the number of host probings. Overcoming host defenses through repeated probings is a previously overlooked potential benefit of superparasitism.
Superparasitism Evolution: Adaptation or Manipulation?
The American Naturalist, 2006
Superparasitism refers to the oviposition behavior of parasitoid females who lay their eggs in an already parasitized host. This often yields intense competition among larvae that are sharing the same host. Why would a female oviposit in such hostile habitat instead of looking for a better quality, unparasitized host? Here we present a continuous-time model of host-parasitoid interaction and discuss alternative scenarios. This model is first used to analyze the evolution of the superparasitism behavior of a solitary proovigenic parasitoid under both time and egg limitation. Then, following the recent discovery by Varaldi et al., we allow the parasitoid to be infected by a virus that alters the superparasitism behavior of its host to enhance its own horizontal transmission. The analysis of the coevolution of this manipulative behavior with the oviposition behavior of uninfected females clarifies and quantifies the conflict that emerges between the parasitoid and its virus. The model also yields new testable predictions. For example, we expect that uninfected parasitoids should superparasite less after coevolving with the manipulative virus. More generally, this model provides a theoretical framework for analyzing the evolution of the manipulation of parasitoid life-history traits by microparasites.
Environmental Entomology, 2010
The oriental army worm, Mythimna separata Walker (Lepidoptera: Noctuidae), was adopted as a host to keep Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) populations in the laboratory, because it can be mass reared. However, wasp cocoon production in this system via single parasitism was not satisfactory. To improve the rearing efÞciency of C. chlorideae on M. separata, we studied the effects of superparasitism on the offspring production of C. chlorideae, as well as the host discrimination ability of the adult wasps in the laboratory. The results showed that, compared with single parasitism, both double and quintuple parasitism signiÞcantly increased C. chlorideae cocoon production in M. separata without a signiÞcant effect on emergence, weight, or sex ratio of adult wasps at the P Ͻ 0.05 level. Host selection experiments suggested that C. chlorideae preferred to lay eggs on unparasitized hosts rather than freshly parasitized hosts but could distinguish neither the 24-h postparasitization hosts from the unparasitized hosts nor the freshly self-parasitized hosts from the conspeciÞcally parasitized hosts. Nochoice behavior tests indicated that C. chlorideae took signiÞcantly longer time to accept the freshly parasitized hosts containing more than two eggs compared with the unparasitized hosts. In the end, superparasitism behavior and its application in the mass rearing of this endoparasitoid are discussed.
Annals of the Entomological Society of America, 1997
When females of Pimpla nipponica Uchida, a solitary parasitoid of various lepi dopterous pupae, were exposed to hosts for varing periods of time, percentage wasp emergence decreased; the percentage immature wasps dying at the egg or early-instar stages increased with increasing exposure periods. Factors influencing the increased wasp mortality were examined. Larval competition occurred b e t w e e n 24 and 48 h after parasitism when 1st instars fought physically with their mandibles. Also, m a n y parasitoid eggs had melanized wounds, developed abnormally and died, indicating that 1st instars attacked and killed conspecific eggs. Superparasitism did not influence the fitness of emerging wasps. Hosts used for host feeding by female wasps yielded fewer and smaller wasps. Thus, host feeding was the major factor influencing offspring survival and fitness when multiple attacks against a single host occurred. Superparasitism, larval competition, and host feeding in solitary parasitoids are discussed in the context of adaptive superparasitism theories and mass-rearing programs.