Bracon wasps for ecological pest control–a laboratory experiment

Biological control of pest insects by natural enemies may be an effective, cheap and environmentally friendly alternative to synthetic pesticides. The cosmopolitan parasitoid wasp species Bracon brevicornis Wesmael and B. hebetor Say (Hymenoptera: Braconidae) use lepidopteran species as hosts, including insect pests like Ephestia kuehniella or Ostrinia nubilalis. Here, we compare the reproductive success of both Bracon species on E. kuehniella in a laboratory experiment. We asked (1) how the reproductive success on a single host larva changes with temperature, (2) how it changes with temperature when more host larvae are present and (3) how temperature and availability of host larvae influence the efficacy of Bracon species as biological control agents. In general, differences between B. brevicornis and B. hebetor have been small. For rearing both Bracon species in the laboratory on one host larva, a temperature between 20–27 °C seems appropriate to obtain the highest number of offspring with a female-biased sex ratio. Rearing the braconid wasps on more than one host larva revealed a higher number of total offspring but less offspring per host larva on average. Again, highest numbers of offspring hatched at 27 °C and the sex ratio was independent from temperature. Although no parasitoids hatched at 12 °C and only few at 36 °C, host larvae were still paralyzed. The efficacy of B. brevicornis was higher than 80% at all numbers of host larvae presented at all temperatures while the efficacy of B. hebetor was less than 80% at 12 °C and 27 °C at low numbers of host larvae presented. In conclusion, practitioners can use either B. brevicornis or B. hebetor at low and high temperatures and at varying host densities to achieve high pest control efficacy.

Notes on Lasioptera rubi (Schrank) (Diptera: Cecidomyiidae) and its larval parasitoids (Hymenoptera) on raspberries in Russia

In this paper, larva and pupa of Lasioptera rubi (Schrank) infected by hymenopteran parasitoids are illustrated. For the first time it is found that Platygaster pelias Walker is a solitary parasite and winters at the embryonal stage inside host larva of L. rubi reared from galls on Rubus idaeus stems in Russia. Lasioptera rubi, Torymus eadyi Graham & Gij swijt and Platygaster pelias Walker are recorded from Russia for the first time.

Sand wasp (Hymenoptera: Crabronidae) parasites emerging from mud wasp nests (Hymenoptera: Sphecidae)—a reliable host record of Thraxan Yeates & Lambkin (Diptera: Bombyliidae: Anthracinae) with description of the pupal exuviae of three Thraxan species

Two female Thraxan sp. (Diptera: Bombyliidae: Anthracinae) emerged from parasitised Pison simillimum Smith (Hymenoptera: Crabronidae) larvae found inside a Sceliphron formosum Smith (Hymenoptera: Sphecidae) mud wasps nest. Thraxan sp. larvae are endoparasites of P. simillimum larvae. The endoparasite pupates inside the host larva, kills it, and emerges free of the host body. We describe and illustrate the pupal exuviae of the newly found species and two known species, T. luteus Yeates & Lambkin and T. misatulus Yeates & Lambkin, and we compare these pupal exuviae to those of Anthrax Scopoli.

Life history of Parnips and the evolutionary origin of gall wasps

By mechanisms that are still unknown, gall wasps (Cynipidae) induce plants to form complex galls, inside which their larvae develop. The family also includes inquilines (phytophagous forms that live inside the galls of other gall inducers) and possibly also parasitoids of gall inducers. The origin of cynipids is shrouded in mystery, but it has been clear for some time that a key group in making progress on this question is the ‘figitoid inquilines’. They are gall-associated relatives of cynipids, whose biology is poorly known. Here, we report the first detailed data on the life history of a figitoid inquiline, the genusParnips. Dissections of mature galls show thatParnipsnigripesis a parasitoid ofBarbotiniaoraniensis, a cynipid that induces single-chambered galls inside the seed capsules of annual poppies (PapaverrhoeasandP.dubium). Galls with pupae ofParnipsnigripesalways contain the remains of a terminal-instar larva ofB.oraniensis. The mandibles of the terminal-instar larva ofP.nigripesare small and equipped with a single sharp tooth, a shape that is characteristic of carnivorous larvae. The weight ofP.nigripespupae closely match that of the same sex ofB.oraniensispupae, indicating thatParnipsmakes efficient use of its host and suggesting that ovipositingParnipsfemales lay eggs that match the sex of the host larva. Dissection of young galls show that another species ofParnips, hitherto undescribed, spends its late larval life as an ectoparasitoid ofIraellahispanica, a cynipid that induces galls in flowers of annual poppies. These and other observations suggest thatParnipsshares the early endoparasitic-late ectoparasitic life history described for all other cynipoid parasitoids. Our findings imply that gall wasps evolved from parasitoids of gall insects. The original hosts could not have been cynipids but possibly chalcidoids, which appear to be the hosts of several extant figitoid inquilines. It is still unclear whether the gall inducers evolved rapidly from these ancestral parasitoids, or whether they were preceded by a long series of intermediate forms that were phytophagous inquilines.

Egg-lying behavior of Anisopteromalus calandrae (Howard), an Ectoparasitoid of Lasioderma serricorne (Fabricius)

This paper describes the egg-laying behavior and reproduction capacity of Anisopteromalus calandrae in laboratory conditions. Anisopteromalus calandrae lay eggs only on the Lasioderma serricorne larvae hiden inside of grains or nests. The maximum lifespan of A. calandrae females was 32 days when they were kept with of aqua feed flour plus honey (30%) and infested with larvae of Lasioderma serricorne. One female laid 71.13 ± 4.24 eggs. The eggs were laid mostly (81.95%) during the first half of the lifespan, with the peak of 7.40 eggs/day on the 9th day. The females usually lay one egg/host larva, but sometimes they lay 2-5 eggs/host larva. They prefer to lay eggs on the 4th larval instar. Citation: Nguyen Thi Oanh, Tran Ngoc Lan, Truong Xuan Lam, 2017. Egg-lying behavior of Anisopteromalus calandrae (Howard), an ectoparasitoid of Lasioderma serricorne (Fabricius). Tap chi Sinh hoc, 39(4): 416-420. DOI: 10.15625/0866-7160/v39n4.10935.* Corresponding author: [email protected] 17 August 2017, accepted 20 November 2017

Higher aggression towards closer relatives by soldier larvae in a polyembryonic wasp

In the polyembryonic wasp Copidosoma floridanum , females commonly lay one male and one female egg in a lepidopteran host. Both sexes proliferate clonally within the growing host larva. Distinct larval castes develop from each wasp egg, the majority being ‘reproductives’ plus some ‘soldiers’ which sacrifice reproduction and attack competitors. Maturing mixed sex broods are usually female biased, as expected when intra-brood mating is common. Pre-mating dispersal followed by outbreeding is expected to increase sexual conflict over brood sex ratios and result in greater soldier attack rates. Owing to sexually asymmetric relatedness, intra-brood conflicts are expected to be resolved primarily via female soldier attack. We observed soldier behaviour in vitro to test whether lower intra-brood relatedness (siblings from either within-strain or between-strain crosses were presented) increased inter-sexual aggression by female as well as male soldiers. As found in prior studies, females were more aggressive than males but, contrary to expectations and previous empirical observations, soldiers of both sexes showed more aggression towards more closely related embryos. We speculate that lower intra-brood relatedness indicates maternal outbreeding and may suggest a rarity of mating opportunities for reproductives maturing from the current brood, which may enhance the value of opposite sex brood-mates, or that higher aggression towards relatives may be a side-effect of mechanisms to discriminate heterospecific competitors.

A new species of Platygaster Latreille (Hymenoptera: Platygastridae) parasitizing Chilophaga virgati Gagné (Diptera: Cecidomyiidae)

Platygaster chilophagae, new species, is described from specimens reared from larvae of Chilophaga virgati Gagné collected and reared in eastern South Dakota. The host larva feeds on the basal meristematic tissues of the inflorescence of Panicum virgatum L. This new species seems to lack immediate affinities with any described Platygaster species in its combination of characteristics, and is compared to and discriminated from six other species. Polyembryony is suggested by the presence of cocoon clusters containing 4–14 pupae from each host larva.