Experience acquisition by Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae)

We investigated experience acquisition (alpha-conditioning) by females of the parasitoid Trichogramma australicum using host eggs of the noctuid moth Helicoverpa armigera (Hübner). We compared the acceptance of a host egg by females with different levels of ovipositional experience. The level of experience was designated using the standard oviposition sequence: (1) host contact (C); (2) host examination (E); (3) drilling (D); (4) full insertion (FI); and (5) oviposition (O). Each treatment consisted of a single experience level, but together these consituted a qualitative behavioural continuum of oviposition experience from naive (N) to experienced wasps. We found that host experience by adult T. australicum females can modify their behaviour. Mean duration of host finding was: N = C > E = D > FI = O. Mean duration of host examination and full insertion were: N = C > E = D = FI = O. Drilling was constant for all experience levels. Experience in drilling of the chorion during the previous host-exposure process represents a critical experience for a female and results in efficient handling and more ready acceptance of a subsequently encountered host egg.     

Ovipositional Synergists and Artificial Diets for Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae)

We studied ovipositional synergists and artificial diets for rearing Trichogramma australicum. Artificial "diet A" included 40% haemolymph of Helicoverpa armigera (Hübner) final instar larvae, 30% of a 10% malt solution in deionised water, 20% chicken egg yolk and 10% Neisenheimer's salt solution with 76 units Penicillin and 76 units Streptomycin/ml diet. Artificial "diet B" was identical except Grace's insect medium® replaced Neisenheimer's salt solution. the number of T. australicum larvae in artificial eggs filled with diet A and diet B was not significantly different (P > 0.05). Significantly fewer (P < 0.05) larvae developed to pupae and adults in artificial eggs filled with diet A. Quantity and quality of artificial diet affected the mortality of T. australicum larvae reared in vitro. Ovipositional synergists included 10% gelatine solution, 10% polyvinyl alcohol solution or 1% agar solution in deionised water. Synergist test-solutions were individually smeared on the external surface of artificial eggs (hemispherical depressions in plastic membrane). Eggs laid and number of T. australicum larvae produced were significantly higher in artificial eggs smeared with gelatine than artificial eggs smeared with polyvinyl alcohol, agar or non-smeared (control) eggs.     

Antennal and ovipositor sensilla of Pseudoligosita yasumatsui (Hymenoptera: Trichogrammatidae)

Pseudoligosita yasumatsui Viggiani and Subba Rao 1978 (Hymenoptera: Trichogrammatidae) is a common egg parasitoid of rice insect pests. The surface morphology of the antenna and ovipositor on P. yasumatsui was examined using scanning electron microscopy. The antenna of P. yasumatsui is geniculate in shape, hinged at the scape-pedicel joint, approximately 190 μm in length and consists of seven antennomeres. In total, the male and female antennae have ten different types of sensilla: trichoid sensilla type 1, 2, 3, 4, 5, 6, campaniform sensilla, basiconic sensilla, and placoid sensilla type 1 and 2. The flagellum of the female antenna is covered with cuticular pores, which are absent on the male antennal flagellum. The distal extremity of its ovipositor stylet has campaniform sensilla and styloconic sensilla. Trichoid sensilla found on its apical abdomen part may play a role in the host detection and egg placement. The types and distribution of antennal and ovipositor sensilla on the parasitoid were discussed.     

Development of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) in Helicoverpa (Lepidoptera: Noctuidae) host eggs

Abstract Morphological studies of development of the egg parasitoid Trichogramma australicum Girault in the cotton bollworm, Helicoverpa armigera (Hübner), were conducted to provide benchmarks for assessing developmental rates in both natural hosts and artificial diets. Observations of living embryos and histological sections show that embryos proceed rapidly through cleavage and blastoderm formation and show a characteristic pinching or rotation 8 h after deposition. Eggs progressively increase in volume, primarily by increasing in diameter at the widest point. At 29 ± 1°C the duration of the egg stage is 22−24 h, the larval stage 27 h, the prepupal stage 50−52 h, and pupa 85 h. Larvae undergo dramatic shape changes as they ingest food but do not show signs of larval moults, reinforcing observations that there is only one larval instar. Criteria for staging the embryonic and postembryonic development in natural hosts will be used for future studies aimed at developing and refining artificial diets for Trichogramma.     

External morphology of antennal sensilla of four species of adult flea beetles (Coleoptera : chrysomelidae : alticinae)

External morphology of antennal sensilla of both sexes of Phyllotetra cruciferae (Goeze) and Psylloides punctulata Melsh, both of which feed on the mustard family Cruciferae, and Epitrix cucumeris (Harris) and Psylloides affinis (Paykell), both of which feed on the nightshade family Solanaceae, was studied using scanning electron microscopy. All belong to Alticinae (Coleoptera : Chrysomelidae). The number and distribution of antennal sensilla were also determined. Eight types of sensilla could be distinguished on the flagella of the species examined: sensilla chaetica; sensilla trichodea I and II; long sensilla basiconica I and II; and short sensilla basiconica I, II and III. The sensilla chaetica are probable tactile mechanosensilla, whereas both types of sensilla trichodea and long sensilla basiconica likely function in olfaction. Suggested functions for the short sensilla basiconica I, II and III include hygro-/thermoreception and chemoreception.The lack of sexual dimorphism in antennal structure and in types as well as number of sensilla, indicates that the sensilla probably have similar functions in both sexes. Probably most of the antennal olfactory sensilla are involved in host location and recognition. Any correlation between number of a particular type of sensillum or total number of all types and general host preference is not apparent.     

Oviposition Behaviour and Reproductive Performance of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) Reared in Artificial Diet

Biotypes of Trichogramma australicum were reared on artificial diet "A", Helicoverpa armigera (Hübner) (natural host) eggs and Sitotroga cerealella (Olivier) (factitious host) eggs. We evaluated the quality of these biotypes by comparing their oviposition behaviour and reproductive performance on H. armigera eggs. Female T. australicum reared in vitro accepted H. armigera eggs for oviposition and displayed similar behavioural components of oviposition to females reared on natural hosts. However, handling time during oviposition in H. armigera eggs by females from in vitro rearing was significantly longer than handling time of females reared on the natural host because the females needed a significantly longer time for host feeding. In vitro reared females produced significantly more progeny and parasitised more H. armigera eggs than the females reared on S. cerealella. Improvements to the artificial diet for T. australicum may reduce handling time of the in vitro reared females and increase the female population. These improvements may include changes in nutrient content and size of the artificial eggs.     

External morphology and distribution of the antennal sensilla of the stonefly,Paragnetina media (Walker) (Plecoptera : Perlidae)

The distribution and external morphology of sensilla on the antennae of nymphal and adult stonefly, Paragnetina media (Plecoptera : Perlidae) were studied with light and scanning electron microscopy. A peculiar arrangement of 3 types of sensilla was observed on the antennae of the nymphs. Thick- and thin-walled sensilla basiconica and coniform sensillar complexes occur in a group, and 6 to 7 such groups are located around the distal margin on the segments in the mid-region of the flagellum. Campaniform sensilla are concentrated in a ring around a crown of thick- and thin-walled sensilla basiconica on the distal end of the pedicel. Two types of trichoid sensilla, long wavy, and stout straight, are present on the flagellum of the nymph. Adult stoneflies have an antennal surface profusely covered only with long and short trichoid sensilla; all other nymphal type sensilla are absent. The lack of nymphal type sensilla on their antennae may be related to the adult's brief, non-feeding terrestrial life.     

Antennal sensilla of female Trichogramma nubilale (Ertle and Davis) (Hymenoptera : Trichogrammatidae) and comparisons with other parasitic Hymenoptera

We describe the external morphology and relative positions of antennal sensilla of female Trichgramma nubilale (Hymenoptera : Trichogrammatidae) by scanning electron microscopy (SEM), and compared the results with 11 similar studies representing 15 species and 8 families within the parasitic Hymenoptera. There are 6 morphologically and structurally distinct structures on female T. nubilale antennae, which are probably sensilla, and one seta and one campaniform-like structure that may have a sensory function. Sensilla pore numbers and positions suggests that the multiporous grooved basiconica (MPG) C, multiporous pitted (MPP) trichodea A and the MPP placodea A have an olfactory function, whereas the MPP trichodea C have a gustatory function. The lack of pores and the presence of a basal socket suggests a mechanoreceptor function for aporous (AP) trichodea B, and the uniporous pitted (UPP) trichodea D, although, the latter also have a minute pore or dimple at the sensillar apex. Positions and numbers of these sensilla, setae and campaniform-like structures were consistent in all the specimens examined. These analyses suggest that antennal sensilla types and relative positions are highly conserved within the genus Trichogramma, and there are broad similarities within the parasitic Hymenoptera.     

豆柄瘤蚜茧蜂触角感受器的扫描电镜观察(英文)

利用扫描电镜对豆柄瘤蚜茧蜂Lysiphlebus fabarum的触角感受器进行了观察, 发现有7 种感受器, 分别为毛形感受器、刺形感受器Ⅰ型、刺形感受器Ⅱ型、锥形感受器、腔锥形感受器Ⅰ型、腔锥形感受器Ⅱ型和板形感受器。毛形感受器是数量最多的感器; 除了腔锥形感受器Ⅱ型只在雌虫触角发现外, 雌、雄触角感受器的类型和结构没有较大的差别, 并且腔锥形感受器Ⅱ是数量最少的感器。     

Sexual dimorphism of antennal and ovipositor sensilla of Tetrastichus sp. (Hymenoptera: Eulophidae)

Tetrastichus sp. (Hymenoptera: Eulophidae) is a primary parasitoid of the Metisa plana (Lepidoptera: Psychidae), an oil palm bagworm. The sensilla on the surface of the antenna and ovipositor of Tetrastichus sp. were examined using a scanning electron microscope. The antennae of both male and female Tetrastichus sp. are geniculate in shape and hinged at the scape-pedicel joint. The female antenna is about 200 µm longer than the male antenna. However, the male antenna has an additional flagellomere compared to the female antenna. In total, eight different types of antennal sensilla were observed on the antenna of Tetrastichus sp.: trichoid sensilla type 1, 2, 3, 4, placoid sensilla type 1 and 2, basiconic sensilla, and campaniform sensilla. The antenna of the female Tetrastichus sp. lacks placoid sensilla type 2 and campaniform sensilla. The distribution and abundance of the antennal sensilla were compared between the male and female Tetrastichus sp. and discussed. On the ovipositor stylet of Tetrastichus sp., coeloconic sensilla, styloconic sensilla and campaniform sensilla were observed. Trichoid sensilla were observed at the medial part of the distal extremity of the ovipositor.     

Ultrastructure of the antennal sensilla of the cockroach-egg parasitoid,Tetrastichus hagenowii (Hymenoptera: Eulophidae)

Eggs of a number of cockroach species are parasitized by Tetrastichus hagenowii. The ultrastructure of the sensilla on the antennae of females and males was examined by scanning and transmission electron microscopy. The females have two types of multiporous plate sensilla while the males have only one. Type 1 is found in females and males and has a relatively thin cuticular wall and many pores, while type 2 is found only in females and has a relatively thick cuticular wall and few pores. Both sexes have nonporous, thick-walled, socketed hairs; multiporous, nonsocketed hairs; multiporous, thick-walled pegs; and terminal hairs. In addition, males have multiporous, nonsocketed, long hairs. The sensilla are similar, in many respects, to the sensilla of other chalcid parasitoids. The antennal sensilla of female T. hagenowii are probably involved in ovipositional behavior. The multiporous, long hairs of the male possibly receive stimuli during mating behavior A chemoreceptive function is proposed for the multiporous plate sensilla.     

External morphology of sensilla in the sacculus of an antennal flagellum of the fruit fly Drosophila melanogaster Meigen (Diptera : Drosophilidae)

Sensilla in the sacculus of an antennal 3rd segment, a funiculus, of the fruit fly, Drosophila melanogaster (Diptera : Drosophilidae) have been examined by scanning electron microscopy. The sacculus was divided into 3 cavities in its interior. A morphologically distinct group of sensilla was present in each cavity. Grooved sensillum (GS), found in the largest cavity, was further subclassified on the basis of the side wall sculpture into 3 subgroups: GS Ia, GS Ib and GS II. GS Ia was 4 μm long and had 10–12 grooves (0.25 μm wide) and GS Ib was 3.8 μm long and had 6–9 grooves (0.25-0.4 μm wide). GS 1a and GS Ib were inferred to be olfactory and thermoreceptive, and olfactory, respectively. GS II was 3.2 μm long, and had 4–5 grooves. Basiconic sensillum (BS), found in the smallest cavity, was 4.5 μm long and had an irregularly sculptured side wall, suggesting the presence of numerous irregular-shaped olfactory pores. Blunt-tipped sensillum (BTS), found in the middle-sized cavity, was 1.9 μm long and had a smooth-surfaced side wall and a button-like structure on its apex. These features suggested that BTS was hygro- and thermoreceptive.     

Gross morphology of multiporous plate sensilla in the Hymenoptera (Insecta)

Both external and internal gross morphology of multiporous plate sensilla were investigated throughout the Hymenoptera, with particular reference to nonaculeate families, using SEM. Several scenarios concerning the origin of multiporous plate sensilla are discussed. Shape, attachment, position, and reinforcing structures, were found to vary between the families, and the possible phylogenetic implications of these are discussed.     

The fine structure of the antennal sensilla of the pine saw flyNeodiprion sertifer (Insecta: Hymenoptera)

Summary There is a considerable sexual dimorphism as regards the development of the antenna inNeodiprion sertifer. In the male this is manifested in a larger antennal surface area and the possession of a great number of long single-walled sensilla (SW 1), which are located on the antennal branches. In the female the antennal branches are vestigial, and the single-walled sensilla, of a second type (SW 2), are shorter and present in lower numbers. Both sexes have in addition four types of sensilla in common:viz. a third type of single-walled sensilla (SW 3), terminal pore sensilla, double-walled sensilla, and poreless sensilla. These four sensillar types are characterized not only by their external appearance but also by their internal morphology. Especially the cells enveloping the sensory cells vary in number and appearance.Supported by joint grants from the Swedish Council for Planning and Coordination of Research, the Swedish Natural Science Research Council, and the Swedish Council for Forestry and Agricultural Research.     

Anatomy of the mouthparts and digestive tract during feeding in larvae of the parasitoid wasp Trichogramma australicum Girault (Hymenoptera : Trichogrammatidae)

To aid in the development of artificial diets for mass rearing parasitioids, we investigated the anatomical changes in the digestive tract during feeding behaviour of larval Trichogramma australicum (Hymenoptera : Trichogrammatidae). Larvae begin to feed immediately upon eclosion and feed continuously for 4 h until replete. Feeding is characterised by rhythmic muscle contractions (ca 1 per s) of the pharynx. Contractions of the pharyngeal dilator muscles lift the roof of the lobe-shaped pharynx away from the floor of the chamber, opening the mouth and pumping food into the pharyngeal cavity. Another muscle contraction occurs about 0.5 s later, forcing the bolus of food through the oesophagus and into the midgut. The junction of fore- and midgut is marked by a cardiac valve. The midgut occupies most of the body cavity and is lined with highly vacuolated, flattened cells and a dispersed layer of muscle cells. In the centre of the midgut, food has the appearance of host egg contents. Food near the midgut epithelial cells has a finer, more homogeneous appearance. This change in the physical properties of the gut contents is indicative of the digestion process. In the prepupa, where digestion is complete, the entire gut contents have this appearance. After eclosion, the vitelline membrane remains attached to the posterior end of the larva. We believe this attachment to be adaptive in two ways: (1) to anchor the larva against the movements of its anterior portion, thereby increasing the efficiency of foraging within the egg; and (2) to prevent a free-floating membrane from clogging the mouthparts during ingestion.     

Functional morphology of antennal chemoreceptors of the parasitoid Microplitis croceipes (Hymenoptera: Braconidae)

The specialist parasitoid, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), uses chemical cues from plants damaged by herbivore-feeding and also plant by-products in host location and acceptance. These chemicals are detected by the wasp's antennae. We conducted scanning and transmission electron microscopy studies of male and female M. croceipes antennae and detected no distinct morphological differences in the chemoreceptors between the sexes. Male antennae are approximately twice as long as female antennae. We found five morphological sensillar types in both sexes: sensilla (s) trichodea were the most abundant and distributed over the whole antenna; s. chaetica were present in low numbers only on the scape and pedicel; and s. basiconica, s. coeloconica and elongated s. placodea were found only on the flagellum. Ultrastructural investigations revealed pore systems on s. basiconica and s. placodea. In s. placodea, sensory neurons run parallel to the longitudinal axis of the sensilla with terminal pores. We recorded responses from single olfactory receptor neurons in s. placodea to two plant-emitted volatiles, cis-3-hexenol and ocimene, and two anthropogenic compounds, cyclohexanone and 2-diisopropylaminoethanol. Male receptor neurons were more sensitive than those of females with significantly higher spike frequency being registered from neurons in males.