Serologic diagnosis of Oestrus ovis (Diptera: Oestridae) in naturally infested sheep

Sera from eighteen control sheep supposed to be free from parasitism by Oestrus ovis Linnaeus, 1761, and from 100 sheep raised in an enzootic area of O.ovis infestations were tested to detect anti-Oestrus antibodies by double immunodiffusion (DD) and indirect haemagglutination (IH) tests with somatic crude antigens from first (L1), second (L2) and third (L3) instar of O.ovis larvae. At necropsy, eighty-eight out of 100 sheep from the O.ovis infested area were found to be parasitized while the eighteen control ovines did not show Oestrus larvae. Examination of the sera from the parasitized sheep by DD showed positive results of 42% for L1, 59% for L2 and 18% for L3. Screening the sera with IH gave sensitivities of 100% for L1, 100% for L2 and 97.7% for L3. Sheep, naturally parasitized by gastrointestinal nematodes, presented no cross immune reactions in DD tests with the three larval stages of O.ovis or with L2 larvae in IH tests.     

The kinetics of specific serum antibodies in sheep infested with sheep bot larvae]

The kinetics of specific antibodies of the blood serum of sheep experimentally infested with 80, 160 and 1000 specimens of Oestrus ovis larvae was examined. The affinity pure serum IgG and the immunoferment analysis (ELISA) were used for qualitative estimation of specific antibodies. It has been shown that the level of specific antibodies correlates with the larval biomass and is connected with ontogenesis of this parasite. The younger animals, which were infested for the first time, are characterized by more intensive production of specific IgG than adult reinfested ones. The ways of immunity response formation in animals infested with Oestrus ovis larvae are considered.     

Biology of Microplitis kewleyi (Hymenoptera: Braconidae): A parasite of Agrotis ipsilon (Lepidoptera: Noctuidae) larvae

Microplitis kewleyi Muesebeck is a gregarious internal parasite of larvae of the black cutworm Agrotis ipsilon (Hufnagel). Studies of the biology of the parasite revealed that there was an inverse relationship between host instar and parasite preference. Duration of development from egg to pupa ranged from 18 days at 27°C to 68.7 days at 16°C. Development from egg to pupa took 13.5–21.6 days when fourth and first instar host larvae, respectively, were parasitized. A larger number of parasites emerged from hosts parasitized in the fourth instar (22.4) than the first instar (11.5). Parasite pupation occurred when the host was in the fifth/sixth instar, depending on the instar parasitized. Thirty‐nine per cent of host larvae exposed as first instars to parasites died before parasite emergence. This decreased to 0% for host larvae exposed as fourth instars. The sex ratio was 1:1.2 (M:F). Thirty‐seven per cent of hosts exposed diurnally were stung, compared to 24% exposed nocturnally. Mean daily progeny was highest (12) on the first day, decreasing to zero after 20 days. Percent host parasitism was also highest on the first day (35%) decreasing to nearly 0% after 18 days. There appear to be three parasite larval instars. Host larvae often remained alive after parasite emergence.     

Sheep and goat immune responses to nose bot infestation: a review

Oestrus ovis L. (Diptera: Oestridae) is a cosmopolitan agent of myiasis in sheep and goats. The parasitic phase begins after adult females deposit first-stage larvae (L1) into the nostrils of hosts; these larvae develop into L2 and L3 in the nasal and sinus horn cavities. Sneezing and nasal discharges are the major clinical signs in infected animals. The pathogenesis of O. ovis infection is caused by: (a) the trauma resulting from the mechanical action of spines and hooks during larval movement on mucosal membranes, and, more importantly, (b) an allergenic reaction provoked by molecules excreted/secreted by larvae, of which salivary antigens are those mainly recognized by the host's immune system. The recruitment of immune reactive cells increases gradually from the nasal to sinus cavities in infected hosts. Mast cells, eosinophils, macrophages and lymphocytes are always more numerous in infected than non-infected animals. Humoral (antibody) systemic response of immunoglobulin G (IgG) usually reaches seroconversion 2-4 weeks post-first infection and the highest levels are observed during the development of L2 and L3 larvae. Local antibody responses include specific IgG, which has been found to negatively correlate with larval survival and development. Hypersensitivity reaction, immunomodulation, immunization trials and mixed infections of O. ovis and helminths are discussed.     

New species of Homidia (Collembola, Entomobryidae) from eastern China with description of the first instar larvae

Morphology of the first instar larvae of Collembola has considerably taxonomical and phylogenetic significance. We describe the first instar larvae for the first time in Homidia. External morphology of first instar larvae and adults of Homidia jordanai sp. n. is described based on observations under light and scanning electron microscopes. Most organs of adults bear considerably more setae than the first instar larvae; in addition, first instar larval Homidia lack labial seta R, seta on tenaculum, mucronal spine, and dental spines. The new species is characterized by weakly pigmented body, long antennae subequal to body in length, 1+1 inner macrochaetae on Abd. III, few inner macrochaetae on posterior Abd. IV, and spiny and short seta pi on dental base. Differences between new species and other two similar ones, taxonomical significance of the first instar larvae and the position of Homidia are also discussed.     

Biology and morphology of the immature stages of Hermeuptychia atalanta (Lepidoptera: Nymphalidae: Satyrinae)

This paper describes the morphology of the immature stages (egg, larva and pupa) and larval behavior of the butterfly Hermeuptychia atalanta, a common and widespread species of satyrinae in South America. Eggs are white and spherical, laid singly on leaves of grasses. The first instar has a light-green body and dark-brown head; all remaining instars present body and head capsule light green. Larvae have no spines, and general morphology is similar to other species of the subtribe Euptychiina.     

Human nasal myiasis due to Oestrus ovis]

One case of human nasal myiasis caused by second and third instar larvae of Oestrus ovis was observed in Lille (North France). Oestrosis is a common myiasis of sheep and goats in Mediterranean and Tropical countries. The authors examine the oestrosis pathogenesis in the usual host (sheep) or in humans, and analyse the epidemiology, the symptomatology and the treatment of human oestrosis.     

The male and female first instar larvae of Anaphes victus and A. listronoti (Hymenoptera, Mymaridae)

 Anaphes victus and A. listronoti are two closely related species, respectively solitary and gregarious parasitoids of eggs of the carrot weevil Listronotus oregonensis (Coleoptera, Curculionidae). Both species are sympatric, and the regulation of super- and multiparasitism that occurs regularly in this host is done by larval fights between the mymariform first instar larvae. The morphology of both male and female first instar larvae of A. victus and A. listronoti is described using scanning electron microscopy. Both species have first instar larvae of the mymariform type and present sexual dimorphism. The main difference between the two species is that larvae of A. victus are clearly segmented while larvae of A. listronoti show no visible segmentation. Male larvae of both species have two types of perioral hooks, longer and less dense dorsal setae than females and developed undertail spines. Female larvae of both species have short abdominal setae. These morphological differences are discussed in the context of intra- and interspecific larval competition. Accepted: 25 May 1997     

Developmental strategy of the endoparasite Xenos vesparum (strepsiptera, Insecta): host invasion and elusion of its defense reactions

To successfully complete its endoparasitic development, the strepsipteran Xenos vesparum needs to elude the defense mechanisms of its host, the wasp Polistes dominulus. SEM and TEM observations after artificial infections allow us to outline the steps of this intimate host-parasite association. Triungulins, the mobile 1st instar larvae of this parasite, are able to "softly" overcome structural barriers of the larval wasp (cuticle and epidermis) without any traumatic reaction at the entry site, to reach the hemocoel where they settle. The parasite molts 48 h later to a 2nd instar larva, which moves away from the 1st instar exuvium, molts twice more without ecdysis (a feature unique to Strepsiptera) and pupates, if male, or develops into a neotenic female. Host encapsulation involves the abandoned 1st larval exuvium, but not the living parasite. In contrast to the usual process of encapsulation, it occurs only 48 h after host invasion or later, and without any melanization. In further experiments, first, we verified Xenos vesparum's ability to reinfect an already parasitized wasp larva. Second, 2nd instar larvae implanted in a new host did not evoke any response by hemocytes. Third, we tested the efficiency of host defense mechanisms by implanting nylon filaments in control larval wasps, excluding any effect due the dynamic behavior of a living parasite; within a few minutes, we observed the beginning of a typical melanotic encapsulation plus an initial melanization in the wound site. We conclude that the immune response of the wasp is manipulated by the parasite, which is able to delay and redirect encapsulation towards a pseudo-target, the exuvia of triungulins, and to elude hemocyte attack through an active suppression of the immune defense and/or a passive avoidance of encapsulation by peculiar surface chemical properties.     

羊狂蝇化蛹、羽化的生物学研究

本文揭示羊狂蝇羽化与环境因素的相关性,幼虫在土壤栖息定位,蛹态,蛹与幼虫大小的相关性,成蝇活动行为和寿命,雌雄蝇比率等生物学特性,为羊狂蝇应用研究提供具有指导意义的基础资料。     

Role of gregarine parasite Ascogregarina culicis (Apicomplexa: Lecudinidae) in the maintenance of Chikungunya virus in vector mosquito

Ascogregarina culicis and Ascogregarina taiwanensis are common gregarine parasites of Aedes aegypti and Aedes albopictus mosquitoes, respectively. These mosquito species are also known to transmit dengue and Chikungunya viruses. The sporozoites of these parasites invade the midgut epithelial cells and develop intracellularly and extracellularly in the gut to complete their life cycles. The midgut is also the primary site for virus replication in the vector mosquitoes. Therefore, studies were carried out with a view to determine the possible role of these gregarines in the vertical transmission of dengue and Chikungunya viruses from larval to adult stage. Experiments were performed by exposing first instar mosquito larvae to suspensions containing parasite oocysts and viruses. Since Ascogregarina sporozoites invade the midgut of first instar larvae, the vertical transmission was determined by feeding the uninfected first instar larvae on the freshly prepared homogenates from mosquitoes, which were dually infected with viruses and the parasite oocysts. Similarly, the role of protozoan parasites in the vertical transmission of viruses was determined by exposing fresh first instar larvae to the dried pellets of homogenates prepared from the mosquitoes dually infected with viruses and the parasite oocysts. Direct vertical transmission and the vertical transmission of CHIK virus through the oocyst of the parasites were observed in the case of Ae. aegypti mosquitoes. It is suggested that As. culicis may have an important role in the maintenance of CHIK virus during the inter-epidemic period.     

Larval morphology and anatomy of the parasitoid Exorista larvarum (Diptera: Tachinidae), with an emphasis on cephalopharyngeal skeleton and digestive tract

The endogenous development of the tachinid gregarious larval parasitoid Exorista larvarum L. (Diptera: Tachinidae) has been analyzed in the last larval instar of a factitious host, the wax moth Galleria mellonella L. (Lepidoptera: Pyralidae), with the use of histological techniques and scanning electron microscopy. This study has focused on the parasitoid internal body structures and their changes during the larval development. The first and second instars are enveloped by a host-derived hemocyte capsule attached to the respiratory funnel via a prominent anal hook located between 2 anal lobes. The third instar abandons the respiratory funnel and migrates free in the body cavity of the already dead host. Emphasis is given to the prominent cephalopharyngeal skeleton, highlighting the morphological aspects of its sclerotized as well as non-sclerotized components. In addition to the cephalopharyngeal skeleton, the anterior third of the larval parasitoid body is occupied by large salivary glands, massive proventriculus, and cerebral ganglia. The extensive digestive tract, which occupies the major part of the body, is differentiated into well-marked individual parts. The abdomen is predominantly filled with the extremely long mesenteron that increases in size during the larval development. The whole body is covered by an apparently thin integument, with strong spines that are especially numerous in the anterior and posterior body parts.     

Characteristics Of Parasitism Of Plutella Xylostella (Lep., Plutellidae) By Oomyzus Sokolowskii (Hym., Eulophidae)

Laboratory and greenhouse studies were conducted on Oomyzus sokolowskii Kurdjumov, a parasite of the crucifer pest Plutella xylostella ( L.). O. sokolowskii preferred the 3^rd and 4^th instar P. xylostella larvae over fresh pupae for parasitization. It is thus a larval parasite. Within the range of 10?C to 35?C, parasitism was positively correlated with temperature. High parasitism at temperatures of 30?C and 35?C indicates that this insect is suitable for the control of P. xylostella in the tropical lowlands. In a no- choice test where only fresh pupae of Cotesia plutellae Kurdjumov, another potentially competing larval parasite of P. xylostella, were offered, O. sokolowskii failed to parasitize pupae of C. plutellae. In a choice test where the 4^th instar P. xylostella larvae and fresh C. plutellae pupae were offered, O. sokolowskii parasitized only P. xylostella larvae. This parasite, therefore, is not a hyperparasite of P. xylostella. When C. plutellae-ovvposited P. xylostella larvae were offered at intervals, O. sokolowskii, parasitized only freshly oviposited host larvae. The longer the period that elapsed after C. plutellae oviposition of P. xylostella larvae, the lesser was the parasitism of these larvae by O. sokolowski.     

Analysis of larval antigens of Oestrus ovis for the diagnosis of oestrosis by enzyme-linked immunosorbent assay

A serodiagnostic test for the diagnosis of infestation by the sheep nasal bot fly, Oestrus ovis (Linné) was examined. The enzyme-linked immunosorbent assay (ELISA) technique was used to analyze and compare the production of immunoglobulin G (IgG) antibodies against excretory-secretory products (ESP) and crude extract (CE) antigens from all the different larval stages of O. ovis in the sera of 276 adult sheep sampled in summer (n = 135) and winter (n = 141). ESP from first stage larvae was the most sensitive, coating antigen in winter and ESP from second stage larvae during summer. The most specific values were obtained by ESP against L1 in winter and by CE against L3 in summer. These results show that the stage of larval development has a significant impact on the humoral immune response over the course of a season. A significant correlation (P < 0.001) was found between the number of O. ovis larvae and the serum antibody levels using all differents antigens, except L3 CE. In Spain, where a long favourable period exists for the evolution and development of the different stage larvae between March and November, the ELISA test using L1 ESP antigen during winter and L2 ESP antigen in summer may be used for ovine oestrosis immunodiagnosis.     

Prevalence and intensity of Oestrus ovis in Akkaraman sheep in the Konya region of Turkey

Slaughterhouse surveys to determine the prevalence and intensity of larval Oestrus ovis Linnaeus (Diptera: Oestridae) in sheep, were conducted monthly for 1 year in Konya, Turkey. A total of 624 sheep, selected at random, were examined and 59% were found to be infested by O. ovis. A total of 8801 larvae were collected, of which 68.9% were first-stage, 19.1% second-stage and 12% third-stage larvae. All three larval stadia were seen in each month of the year. The larval intensity for infected sheep was 23.9, with 16.48 L(1), 4.55 L(2) and 2.87 L(3). The monthly prevalence ranged from 34.6% in January to 76.9% in October. The largest number of larvae (180) was obtained from a sheep in August (122 L(1), 52 L(2) and 6 L(3)). The infestation rate was higher in 4 - 6-year-old sheep, at 72.6%. The infestation rates were 64.4% in female and 47.5% in male sheep.     

Postembryonic development of the wing imaginal discs in the female wingless bagworm moth Eumeta variegata (Lepidoptera,Psychidae)

The process of wing disc development and degeneration in the bagworm moth Eumeta variegata was investigated histologically. Morphological differences between two sexes first appear in the penultimate (eighth) larval instar. In the male, wing discs proliferate rapidly in the penultimate larval instar and continue proliferating; a conspicuous peripodial epithelium forms in the last (ninth) larval instar. The hemopoietic organs break down in this stage and disappear completely by the prepupal stage. In the female, in contrast, the wing discs remain as in the previous (seventh) instar, without proliferation of cells inside. No peripodial epithelium forms in the penultimate instar or later. Hemopoietic organs are still attached to the wing discs in the last larval instar and the entire wing discs transform into a plain, thick epidermis in the prepupal period. It is suggested that the hemopoietic organs may prevent the wing discs from developing in E. variegata.