Electroantennograms (EAGs) were recorded from two predatory insect species, the twelve-spotted lady beetle, Coleomegilla maculata and the green lacewing, Chrysoperla carnea in response to semiochemicals emitted from one of their prey species, the pea aphid Acyrthosiphon pisum and their host plant. EAG responses were also recorded from C. maculata in response to extracts from individuals of the opposite sex and to extracts from an herbaceous plant, catnip Nepeta cataria. Extracts of catnip and two sex pheromone components of aphids, (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol, elicited significant EAG responses from the antennae of both predatory species. Of 10 corn volatile compounds tested, C. carnea adults responded most strongly to 2-phenylethanol and (E)-β-farnesene. A significant difference in EAG response to extracts of corn leaf collections was observed between male and female C. carnea. In C. maculata, significant EAG responses were elicited by most of the tested corn volatile compounds, except α-pinene and (E)-2-hexenal. The highest EAG responses were observed in response to (E)-β-farnesene, α-terpineol, 2-phenylethanol, and β-caryophyllene. Sexual differences in EAG responses of C. maculata were only found in response to 1-octen-3-ol. Male antennae of C. maculata produced significant EAG responses to extracts from conspecific females, but not to males, which indicates that some chemicals from females could be involved in sexual communication. A significant EAG response also was recorded in response to the extracts of fluids produced during “reflex bleeding.” Male and female antennae of both species exhibited similar dose–response curves to most of the selected compounds, although female C. maculata antennae exhibited higher thresholds in response to several compounds including α-terpineol, (Z)-3-hexenol, and (4aS,7S,7aR)-nepetalactone. Field tests showed that 2-phenylethanol was highly attractive to both sexes of the two investigated species. Only C. maculata was attracted to traps baited with α-terpineol.

Olfactory Reactions of the Twelve-Spotted Lady Beetle, Coleomegilla maculata and the Green Lacewing, Chrysoperla carnea to Semiochemicals Released from Their Prey and Host Plant: Electroantennogram and Behavioral Responses

Fine structure of antennal sensilla basiconica and their detection of plant volatiles in the eucalyptus woodborer, Phoracantha semipunctata Fabricius (Coleoptera: Cerambycidae).

Manganese and zinc in the ovipositors and mandibles of hymenopterous insects

The antennal receptors of the adult male and female ladybird beetle, Semiadalia undecimnotata (Coleoptera: Coccinellidae), were examined by scanning and transmission electron microscopy. Twelve types of receptors were characterized and grouped into 5 morphological classes: Bohm, trichoid, coeloconic, basiconic, and chetiform sensilla. Sensory function was determined on the basis of sensillar ultrastructure and electrophysiological response. Olfactory sensilla are confined in both sexes to the 2 terminal antennal segments. In contrast, gustatory and mechanosensitive organs are present along the entire length of the antennae. Sexual dimorphism of antennal receptors is limited to the latter 2 functional classes. The principal characteristics of this dimorphism are the following: a) males possess 540 sensilla (all types), while females possess only 500; b) males exhibit 2 types of taste receptors not present in females; c) females exhibit one type of mechanoreceptor absent in males; d) the 3 sex-specific types of sensilla, which occupy the same position in males and females, are confined to the inner side of the antennae. The possible role of male-specific sensilla in intersexual communication is discussed.

Antennal sensilla and sexual dimorphism of the adult ladybird beetle Semiadalia undecimnotata Schn. (Coleoptera: Coccinellidae)

The ultrastructure and distribution of sensilla on the antennae of the cabbage stem flea beetle, Psylliodes chrysocephala, were investigated using scanning and transmission electron microscopy techniques. Eight different sensillar types were distinguished. These were; hair plate sensilla, sensilla chaetica, three types of sensilla trichodea, sensilla basiconica, grooved peg sensilla and styloconic sensilla. The sensilla chaetica are known to be gustatory receptors. Ultrastructure indicates that the hair plate sensilla and sensilla trichodea type one are probably mechanoreceptors, whilst the sensilla styloconica are probably thermo-hygro receptors. These thermo-hygroreceptors are unusual in that they are innervated by two sensory cells (one hygroreceptor and one thermoreceptor) rather than the more usual triad. The remaining four sensillar types all have a porous hair shaft, indicating an olfactory role. One of these (the grooved peg sensillum) may also have a thermoreceptive function. No sexual dimorphism was found in the structure, number or distribution of the antennal sensilla.

Functional anatomy of sensory structures on the antennae of Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae)

The ultrastructure of integumentary glands of the adult ladybird, Semiadalia undecimnotata (Coleoptera : Coccinellidae) is described. Two types of glands can be found distributed over the head, thorax, and abdomen: glands without ducts and glands with secretory ducts. Glands without ducts consist of a single cell and a secretory apparatus located within the thickness of the cuticle and equipped with a cuticular cribriform plate; this cribriform plate separates 2 superimposed cavities, and epicuticular filaments fill the lower cavity. Glands without ducts are thought to release volatile pheromones. Glands with a duct appear to be made of 2 kinds of cells: one cell forms the receiving duct and later synthesizes the secretory products, one (or more) cell makes the evacuating duct. Their secretions are abundant and released on the surface of the cuticle in the shape of tortuous cylinders, which are resistant to acetone treatment. Glands without ducts and glands with secretory ducts correspond, respectively, to classes 1 and 3 gland cells according to the nomenclature of Noirot and Quennedey (1974, Annu. Rev. Entomol. 19 : 61–80).

Morphology and ultrastructure of integumentary glands of Semiadalia undecimnotata schn. (Coleoptera : Coccinellidae)

We describe the fine structure of the vitelline membrane, the chorion and the serosal cuticle of the egg of Korscheltellus lupulinus L. (Lepidoptera: Hepialidae). We studied the details of secretion and morphogenesis of the vitelline membrane. The follicle cells produce the vitelline membrane material, while the oocyte controls the morphogenesis of the envelope. Structural changes were observed in the vitelline membrane. For example, thickening before oviposition and melanization and sclerotization after oviposition. A crystalline material was found to be a constituent of the chorion of this egg. The serosal cuticle resembles an endocuticular material of insect integument.

Morphogenese de l'enveloppe vitelline, ultrastructure du chorion et de la cuticule serosale chez korscheltellus lupulinus L. (Lepidoptera : Hepialidae)

The formation of the vitelline membrane of the eggs of Lepidoptera is not related to sperm penetration, male glandular secretions, or passage of egg through the ovipositor. The formation of the vitelline membrane and accompanying ultrastructural changes seem to be controlled by a factor produced by the oocyte. These observations were made in 15 species of Lepidoptera, including 2 parthenogenetic ones. The vitelline membrane of Lepidoptera could be homologized with a fertilization membrane.

Déterminisme de la transformation de l'enveloppe vitelline des oeufs de lépidoptères

L'ovipositeur de 1 symphyte et de 12 apocrites parasitoides primitifs de la famille des Ichneumonidae a ete observe en microscopie electronique a balayage et, pour 2 especes, en coupes semi-fines. L'etude revele l'existence de trachees closes dans les 3 paires de valves et d'un systeme secreteur dans les 2 paires de valves coaptees en stylet perforant. Le role des trachees est discute ainsi que celui du systeme secreteur aboutissant a des pores evacuateurs sur les lancettes des valves qui occupent tres exactement l'emplacement des organes sensoriels chimio-recepteurs connus chez les especes evoluees depourvues de cet appareil secreteur. Ces donnees de micromorphologie etayent la phylogenie au sein des hymenopteres, des symphytes aux apocrites parasitoides primitifs.

Roger Barbier

Papers

Antennal sensilla and sexual dimorphism of the adult ladybird beetle Semiadalia undecimnotata Schn. (Coleoptera: Coccinellidae)

Morphology and ultrastructure of integumentary glands of Semiadalia undecimnotata schn. (Coleoptera : Coccinellidae)

Morphogenese de l'enveloppe vitelline, ultrastructure du chorion et de la cuticule serosale chez korscheltellus lupulinus L. (Lepidoptera : Hepialidae)

Déterminisme de la transformation de l'enveloppe vitelline des oeufs de lépidoptères

Micromorphologie de l'ovipositeur des hyménoptères et évolution des symphytes phytophages aux apocrites parasitoïdes