Anatomical impact and notes on viviparous development related to infestation by neotenic females of Stylops advarians (Strepsiptera: Stylopidae) on adult female Andrena milwaukeensis (Hymenoptera: Andrenidae)

Stylops advarians Pierce (Strepsiptera: Stylopidae) is a prevalent parasite of adult Andrena milwaukeensis Graenicher (Hymenoptera: Andrenidae) in Saskatoon, Saskatchewan, Canada. By dissecting adult bees and examining histological sections, we sought to determine how neotenic females of S. advarians impact female hosts of A. milwaukeensis anatomically. Adult bees with 1–3 females of S. advarians within their gasters were compared to nonstylopised bees (control). The presence of a single female parasite inhibited development of the host’s ovaries. The bee’s foregut shifted laterally when one parasite occupied the gaster and ventrally when two or three were present, thereby reducing the crop’s expandable capacity and the amount of nectar and pollen that stylopised bees can ingest. The midgut and hindgut were less significantly affected by stylopisation. Female parasites typically occupied the host’s gaster dorsolaterally, where each was supported by one of the host’s air sacs. If a third female parasite was present, she resided dorsally along the midline of the host’s gaster, mostly supported by the two female parasites to either side. Asynchronous development within neotenic female parasites was demonstrated, wherein mature first-instar larvae occupied the cephalothorax and abdomen at the same time that the adult female was still supporting multiple embryos.

Density of Diachasmimorpha longicaudata (Ashmead) and host Ceratitis capitata (Wied) larvae for the increase of parasitoid female production

ABSTRACT: The objective of the present study was to evaluate the ratio of Ceratitis capitata larvae/female of Diachasmimorpha longicaudata that results in the increase of parasitism and the production of females in the progeny. We used 8-day-old copulated D. longicaudata females with oviposition parasite experience and third instar larvae of C. capitata from rearing stock maintained at the Laboratory of Biological Control of Universidade Estadual de Montes Claros (Unimontes). Five densities of C. capitata larvae (10, 20, 30, 40, and 50) were offered to parasitoid females that were at five different densities (1, 2, 5, 10, and 15). The larvae were exposed to the parasitoid females by means of “parasitism units” in adapted cages for 1 hour. Sex ratio, percentage of parasitism, and pupal mortality were evaluated. Both host larval density and female parasite density influenced parasitism, female progeny production, and pupal mortality. Higher female production was observed in the progeny in ratios of 1:1 and 2:1 (larvae/females). Ratios above 1:2 reduced the sex ratio, and ratios below 1:1 caused high pupal mortality rates. The females had higher parasitism activity when they were in groups dividing the same space. Equal ratios of Ceratitis capitata larvae and parasitoid females resulted in improved efficiency in progeny females.

Relationships of the branchial parasite Bopyrinella thorii (Isopoda, Bopyridae) and its host Thor floridanus (Decapoda, Hippolytidae)

Morphometric data are presented for developmental stages ofBopyrinellathorii(Richardson, 1904), obtained from 380 individuals ofThorfloridanusKingsley, 1878 infested by this parasite and collected by trawl net in Bahía de la Ascensión, Quintana Roo, Mexico. The close relationships between the sizes of host and parasite () and between sizes of the two sexes of the parasite () suggest the simultaneous growth of host and parasite and the permanence of the pairing of a male and female parasite throughout their lives. Cryptoniscus larvae ofB. thoriiwere sometimes attached intramuscularly to other body parts than the host’s gill chambers. Mature females unpaired with a male had ovarian activity visible through their exoskeleton, which reveals thatB. thoriicould produce oocytes even in the absence of a male. Bilateral double infestation, present in 4.2% of theT. floridanusspecimens analysed, was more frequent in smaller size classes of the host.

The fine structures of Cystocaulus ocreatus (Nematoda: Protostrongylidae) and the related lung pathology

In the present study, the fine surface structures of Cystocaulus ocreatus and its worm as well as brood nodules obtained from the lung of Akkaraman sheep are demonstrated by scanning electron and light microscopy. The mouth of the parasite obtained from the worm nodules is located at the anterior tip and encircled by a collar of tissue. The mouth opening appears as three slits conjoined in the shape of a capital case letter Y, creating three lips. The mouth is surrounded by six papillae just behind the collar. The anterior end was similar in both sexes and covered by numerous wrinkles. Female parasite has a bell-shaped pro-vagina. The posterior end of the female parasite was sharply pointed. The male parasite has a bursa. In the worm nodule, curled parasites were enclosed by a capsula and no eggs and larvae of the parasite were observed. In the brood nodule, heavily affected alveoli and bronchioles contained excessive amounts of larvae and eggs.

STUDIES ON CHELONUS SP. THE PARASITE OF THE COCONUT MOTH BATRACHEDRA ARENOSELLA WALKER

An experiment was conducted at a coconut pest laboratory at Nita, elevation 250 m, Sikka regency, Flores island, province of East Nusa Tenggara, to study mass production of Chelonus parasite by using Phthorimaea operculella Zeller as its host, in an effort to control the coconut moth, Batrachedra arenosella Walker, biologically. Results of the experiment showed that the parasite could be produced in laboratory by using P. operculella as the host and a 10% solution of honey as food for both parasite and the adult host. A female parasite gave an average of 14 offspning during their lives with a sex ratio of 2.27:1, between male and female. The sex ratio of the same parasite in the field with B. arenosella as its host was 1:1. The incubation period of the parasite in laboratory was 26 days for males and 27 days for females. The sex ratio of the moth in the field as 1: 1.26.

Physiological role of HMG-CoA reductase in regulating egg production by Schistosoma mansoni

Pathological lesions observed in humans infected with Schistosoma mansoni are due to the eggs produced by the female parasite. Mevinolin, a potent inhibitor of the enzyme hydroxymethylglutaryl-CoA (HMG-CoA) reductase, blocks egg production by this parasite. In this report, we demonstrate that cholesterol precursors, mevalonate and farnesol, stimulate egg production by the female parasite and that these precursors can reverse the mevinolin-induced inhibition of egg production. Because the parasite cannot synthesize cholesterol, we incubated parasites in a culture media containing radiolabeled acetate with and without mevinolin. We isolated nonsterol lipids from the parasite and observed that mevinolin dramatically reduced the conversion of acetate into the polyisoprenoid (dolichols) lipids of the parasite. Dolichols and other nonsterol lipids did not stimulate egg production. HMG-CoA reductase activity was observed in homogenates of the parasite and was inhibited by mevinolin (Ki = 52 nM), but its activity was tripled when the parasite was chronically exposed to low doses of the drug. Parasites with increased reductase activity produced five to six times more eggs. Lastly, chronic administration of large doses of mevinolin to infected mice resulted in a marked reduction of the pathology associated with the infection. These results suggest that egg production in S. mansoni is associated with the parasite's HMG-CoA reductase activity and that a nonsterol lipid produced in the biochemical pathway regulated by this enzyme stimulates egg production.

FECUNDITY, LONGEVITY, AND SEX RATIO OF APHIDIUS NIGRIPES (HYMENOPTERA: APHIDIIDAE) PARASITIZING DIFFERENT STAGES OF ITS HOST, MACROSIPHUM EUPHORBIAE (HOMOPTERA: APHIDIDAE)

The longevity and age specific fecundity, as well as the sex ratio of the progeny, were obtained for Aphidius nigripes Ashmead females given access to the five developmental stages of the potato aphid, Macrosiphum euphorbiae (Thomas). Neither female longevity nor fecundity, as measured by the total number of aphids parasitized, were significantly different for the various host stages. The percentage of females in the progeny decreased as the female parasite aged, and the overall sex ratio of progeny was significantly affected by the host stage attacked although no direct relationship with host size was evident. However in a separate experiment where parasitism was controlled (females not permitted to attack more than 10 hosts per day), the host stage (size) significantly affected the sex ratio of progeny, with more females emerging from larger than smaller hosts.These data indicate that all developmental stages of M. euphorbiae, when presented separately, are suitable to A. nigripes.

SEX RATIO VARIABILITY OF MUSCIDIFURAX ZARAPTOR (HYMENOPTERA: PTEROMALIDAE)

Females of Muscidifurax zaraptor K. & L. produce a smaller percentage of female progeny as the ratio of ovipositing females to hosts (house fly pupae) increases. Delays in oviposition are apparently responsible for the sex ratio change, because they reduce the percentage of fertilized eggs, i.e. female eggs, that the parasites lay. Delays increase in frequency as the parasite:host ratio increases, and result mostly from interference among the ovipositing females; the interference is mostly or entirely physical. Solitary females of M. zaraptor produce slightly fewer though not significantly fewer female progeny when low host densities delay oviposition; more tests would be required to confirm this effect. There is no evidence for differential survival of the male and female parasite larvae on superparasitized hosts.