Norio Arakaki

Wolbachia-induced parthenogenesis in the egg parasitoid Telenomus nawai

Two egg parasitoid species, Telenomus nawai and Telenomus spec. are similar morphologically but they have been treated as different species because of their different reproductive forms, arrhenotoky and thelytoky. Male progeny were produced from the thelytokous colony of Telenomus spec. (TT) by heat and antibiotic treatments. These males mated successfully with females of arrhenotokous colony of T. nawai (AT) and the females produced on average 19.1% males. This percentage did not differ from that obtained from AT females mated with AT males (19.4%). Diagnostic PCR indicated that TT is infected with Wolbachia; antibiotic treatments eliminated Wolbachia from TT. These facts suggest that Wolbachia causes thelytoky and Telenomus spec. (TT) is conspecific with T. nawai (AT).

Phoretic egg parasitoid,Telenomus euproctidis (Hymenoptera: Scelionidae), uses sex pheromone of tussock mothEuproctis taiwana (Lepidoptera: Lymantriidae) as a kairomone

The phoretic egg parasitoid,Telenomus euproctidis Wilcox (Hymenoptera: Scelionidae) was found more frequently on virgin than on mated female moths ofEuproctis taiwana (Shiraki) (Lepidoptera: Lymantriidae), when virgin and mated moths were exposed concurrently in the field for 24 hr. A synthetic component of the moths sex pheromone. (Z)-16-methyl-9-heptadecenyl isobutyrate, attracted both the wasp,T. euproctidis, and maleE. taiwana. These findings suggest thatT. euproctidis uses the sex pheromone of the female moth,E. taiwana, as a kairomone to locate a host female moth and through her the host eggs.

Mating Disruption for Control of Melanotus okinawensis (Coleoptera: Elateridae) with Synthetic Sex Pheromone

Abstract A mating disruption experiment to control Melanotus okinawensis Ohira (Coleoptera: Elateridae) was conducted at a sugarcane (Saccharum spp.) field and a wild Japanese pampas, Miscanthus sinensis Anderss, grassland on Minami-Daito Island (3,057 ha) from 2001 to 2007. The sugarcane field and the pampas grassland were treated with synthetic sex pheromone that evaporated from a polyethylene tube dispenser. The mean total catches obtained by monitoring traps in the sugarcane fields decreased by 96.1% in 2001 from the previous year on Minami-Daito Island. The mean total trap catches in the treated area further decreased by 74.0% from 2001 until 2007 as cumulative effects. Simultaneously, the number of adults captured by hand decreased from 4.7 per sugarcane field in 2001 to 0.5 in 2007 (89.3% reduction), whereas those captured in the untreated area (Miyagi Island) did not show such a decrease. The mating rates were significantly lower in the females captured in the treated area (14.3–71.4%) than those in the untreated area (96.9–100%). However, the amount of the decrease in the trap catches was relatively small at first (39.6% reduction) in the Japanese pampas grassland on the periphery of the Island. This was probably due to the loss of pheromone substance caused by the strong seasonal wind in the periphery. However, mean total trap catches at the periphery also decreased within several years; significant decreases were detected until 2003, 2006, and 2007. These results indicated that the mating disruption effectively reduced an isolated population of M. okinawensis.

Posticlure: a novel trans-epoxide as a sex pheromone component of the tussock moth, Orgyia postica (Walker)

Abstract A single EAG-active component was found in a pheromone extract from virgin females of the tussock moth, Orgyia postica . This compound named posticlure possesses a trans -epoxy ring and was identified as (6 Z ,9 Z ,11 S ,12 S )-11,12-epoxyhenicosa-6,9-diene by means of GC-MS, 1 H NMR and chiral HPLC analyses, and further chemical derivation followed by the GC-MS analysis. In a field test with the pheromone synthesized stereoselectively, the male moths were specifically attracted to the (11 S ,12 S )-isomer but not to the antipode.

Two regional strains of a phoretic egg parasitoid, Telenomus euproctidis (Hymenoptera : Scelionidae), that use different sex pheromones of two allopatric tussock moth species as kairomones

The egg parasitoid, Telenomus euproctidis Wilcox (Hymenoptera: Scelionidae), is phoretic on females of two allopatrically distributed tussock moths, Euproctis pseudoconspersa (Strand) and Euproctis taiwana (Shiraki) (Lepidoptera: Lymantriidae). Crossing experiments between the two regional parasitoid strains indicated no evidence for their reproductive isolation. More wasps were found on the locally occurring host, E. pseudoconspersa, than on E. taiwana, when virgin females of the two moth species were exposed concurrently in the field for 24 hr in Ibaraki Japan. In Ibaraki, many wasps were caught in traps baited with the synthetic sex pheromone of E. pseudoconspersa, 10,14-dimethylpentadecyl isobutyrate (10Me14Me-15:iBu), but none with that of E. taiwana, (Z)-16-methyl-9-heptadecenyl isobutyrate (16Me-Z9-17:iBu) or blank traps. In Okinawa, Japan, more wasps were found on E. taiwana than on E. pseudoconspersa, and many wasps were caught in traps baited with 16Me-Z9-17:iBu, but only a few with 10Me14Me-15:iBu, and none with blank traps. These results suggest that local wasp strains discriminate between the two sex pheromones, and they strongly prefer the sex pheromone of the moth occurring at their location.

Sexually differentiated functions of female-produced pheromone of the black chafer Holotrichia loochooana loochooana (Sawada) (Coleoptera: Scarabaeidae)

Summary.Both male and female Holotrichia loochooana loochooana (Sawada) (Coleoptera: Scarabaeidae) were attracted with female-produced pheromone, anthranilic acid (2-aminobenzoic acid), in the field. Male chafers were observed to apparently directly locate cotton balls impregnated with 1 to 10 mg of pheromone. In contrast, females never directly oriented to the treated balls but landed 0.2-1.5 m away and exposed their abdominal glands in a calling posture, which occasionally resulted in aggregation of both females and males. This suggested the mating aggregation of this species could be primarily induced by pheromone released by females. A hypothesis for adaptability of female aggregation is proposed and discussed.

A two‐step mechanism controls the timing of behaviour leading to emergence from soil in adult males of the scarab beetle Dasylepida ishigakiensis

Adults of the white grub beetle Dasylepida ishigakiensis Niijima et Kinoshita (Coleoptera: Scarabaeidae) emerge from the soil around dusk for mating on subtropical islands. The present study examines the factors controlling the emergence of males in the laboratory. There are two steps involved. Standby behaviour (i.e. insect head appears at the soil surface) can be observed for several hours before the beetles actually emerge for mating. The standby behaviour is facilitated by warm conditions, although the proportion of standby individuals is influenced not only by the temperature on that day, but also by that on the previous day. Experiments in which beetles are exposed to photoperiod and thermoperiod combinations, in and out of phase, show that temperature is more important in inducing standby and emerging behaviour than light alone. For the second step, factors such as temperature, light and the presence of the female sex pheromone determine whether males will leave the standby position and emerge onto the ground. The female sex pheromone stimulates standby beetles to exhibit emerging and wing vibration behaviours, although the effect depends on when it is presented to beetles. Beetles burrow back into the soil; this behaviour is influenced by illumination and time of the day but not by temperature. The results suggest that D. ishigakiensis possesses a sophisticated mechanism controlling male emergence from the soil.

Effect of colour on male orientation to female pheromone in the black chafer Holotrichia loochooana loochooana

Summary.Under field conditions significantly more black chafer, Holotrichia loochooana loochooana (Sawada) (Coleoptera: Scarabaeidae) males landed on black and gray sources than white ones containing 10 mg of female pheromone, anthranilic acid. When a broader spectrum of colours was tested the frequency of male landing was intensively proportional to as the lightness of the colour of the lures. These findings demonstrated that mate location by H. l. loochooana males is dependent on both olfactory and visual stimuli of the source. In contrast, female aggregation was not affected by colour.

Anthranilic acid: a free amino‐acid pheromone in the black chafer, Holotrichia loochooana loochooana

Summary. Ether extract of the abdominal gland of female black chafers Holotrichia loochooana loochooana (Sawada) (Coleoptera: Scarabaeidae) induced a series of pre-mating behaviors that included short-distance orientation, mounting and abdominal bending toward females in the laboratory. When the extract was chromatographed on a silica gel column, the activity was eluted with 50% ether in hexane and ether fractions. GC-MS analyses revealed that both the active fractions contained anthranilic acid (2-aminobenzoic acid) as a major compound. When partitioned to basic, acidic and amphoteric fractions, pheromonal activity was observed with the latter two fractions and anthranilic acid was detected in these fractions by HPLC analyses. The amount of anthranilic acid in the female extract was estimated to be ca. 1.3 μg/female. Authentic anthranilic acid induced pre-mating behavior in males of at levels equal to that elicited by the compound in the extract. It also attracted male beetles to the traps in the field.

Factors influencing adult emergence from soil and the vertical distribution of burrowing scarab beetles Dasylepida ishigakiensis

The present study investigates the emergence of adult white grub beetles Dasylepida ishigakiensis Niijima et Kinoshita (Coleoptera: Scrabaeidae) from soil as well as their burrowing behaviours. ‘Standby behaviour’ (i.e. adults come to the soil surface where they expose their heads) is shown in the field and, along with emergence behaviour, is entrained by LD photocycles. These 24‐h rhythms persist after transfer to continuous light conditions for 2 days. By contrast, beetles transferred from LD photocycles to continuous dark conditions fail to show standby behaviour; thus, it appears to be manifested only in the presence of illumination. Under dark conditions, beetles emerge completely from the soil directly at the time when standby behaviour is otherwise expected to occur. Emerged adults then burrow back into the soil before dawn. Virgin and mated males, as well as virgin females, which are expected to emerge from the soil for mating on later evenings, burrow to a relatively shallow depth (<2 cm), whereas mated females burrow deeper (2–10 cm). Soil properties such as moisture, grain size, topography and temperature influence the burrowing behaviour and the depths that the beetles reach.