No abstract

The occurrence of a kairomonal response of the parasitoid Anagyrus spec. nov. near pseudococci (Hymenoptera: Encyrtidae) to (+)‐(1R,3R)‐cis‐2,2‐dimethyl‐3‐isopropenyl‐cyclobutanemethanol acetate (PcA, namely, planococcyl acetate) and (S)‐(+)‐lavandulyl senecioate (LS), the respective female sex pheromones of its hosts, the citrus mealybug, Planococcus citri (Risso) and the vine mealybug, Planococcus ficus (Signoret) (Homoptera: Pseudococcidae) was investigated. Attraction to the pheromones was tested by employing pheromone traps in field trials and by static air olfactometer bioassays in the laboratory. Female wasps showed a significant response to LS, in both field and olfactometer experiments. No significant response was registered to the sex pheromone of P. citri. Despite the similarity between the structures of LS and its analogue (S)‐(+)‐lavandulyl isovalerate (LI), no significant response to the latter compound was observed. It seems that differences between the structures of the carboxylate moiety of the respective molecules (LS and LI) markedly affect the kairomonal attractiveness to the parasitoid. The kairomonal response of Anagyrus spec. nov. near pseudococci was neither influenced by the host habitat nor by the host species on which it developed. This suggested innate behaviour of Anagyrus spec. nov. near pseudococci, possibly derived from evolutionary relationships between the parasitoid and P. ficus. The practical implications of the results are discussed.

No abstract

Stereoisomers of 4-methyl-3-heptanol are major components of aggregation pheromones of bark beetles and trail pheromones of ants. Recently, (3S,4S)-4-methyl-3-heptanol (I) has been tentatively identified as the main component of the aggregation pheromone of the almond bark beetle, Scolytus amygdali (Coleoptera: Scolytidae). The four stereoisomers of 4-methyl-3-heptanol were prepared and bioassayed. Key steps included preparation of chiral 4-methyl-3-heptanones using SAMP and RAMP reagents, reduction to the corresponding alcohols, and stereospecific transesterification with vinyl acetate with lipase AK catalysis. In field tests, only (3S,4S)-4-methyl-3-heptanol attracted beetles in combination with the synergist (3S,4S)-4-methyl-3-hexanol, whereas (3R,4S)- and (3R,4R)-4-methyl-3-heptanols were inhibitory.

No abstract

A simple synthesis of the pheromone of the citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), has been developed. Various factors affecting capture of males have been assessed to optimize the trap design and to develop a lure with high efficacy and longevity. Male capture was the same with the racemic and chiral pheromone; technical pheromone (85% purity) was statistically as attractive as pure pheromone (97%). A special formulation was used to determine the actual release rate of the pheromone under field conditions as related to male capture. Generally, plate traps caught more males than delta traps, and large traps caught more than small ones. The effects of aging on the performance of three types of rubber dispensers were evaluated. It was found that the American dispenser displayed the most consistent trapping performance and could be used for monitoring for at least 16 wk with a load of 200 microg of pheromone. The dose-response of the males to sex pheromone was tested within the range of 25-1,600 microg.

The vine mealybug (VM), Planococcus ficus (Signoret), is a worldwide pest and affects mainly grapevine and figs. In Israel, (S)-lavandulyl senecioate [(S)-LS] and (S)-lavandulyl isovalerate [(S)-LI] were identified from VM reared for several generations on potato sprouts, when compared with the identification of only (S)-LS from feral females. Racemic lavandulyl senecioate (LS) can be used for fieldwork because the unnatural enantiomer is benign and does not affect the activity of the pheromone. Lures loaded with 200 lg of LS remained active for 24 weeks but it is recommended to replace lures after 12 weeks to preserve constant and high attractiveness. Delta sticky traps, baited with 50 or 200 lg of LS were used to determine the daily flight pattern and the seasonal flight activity including vine plant infestation. A positive correlation between peak mealybug density and male capture was observed strengthening the usefulness of the pheromone traps for monitoring the pest. Addition of racemic or the two enantiomers of lavandulyl isovalerate (LI) to LS decreased the capture of VM males. The level of inhibition varied during [2003][2004]. Both enantiomers of LI displayed the same antagonistic activity. Addition of (S)-lavandulol to the pheromone resulted in shutdown of the traps. Inhibition by the antipode, (R)-lavandulol, was moderate indicating a certain degree of chiral discrimination.

The physiological age of adult males of seven mealybug species was measured in relation to the elongation of the male pair of the waxy caudal filaments. These filaments begin to emerge after eclosion and reached their maximum length from 29.4-46.6 h. The studied males were divided into three age groups, expressed as percentages of the total waxy caudal filaments length. Attraction to a sex pheromone source was significantly higher in the oldest male group (maximum filaments growth) compared with youngest one. Only the oldest male group copulated successfully; few of the younger males tested displayed 'courtship' behavior towards conspecific virgin females. The calculated duration of the sexually active phase of the adult male life cycle varied among species ranging from 34.4 to 46.6 h. There were marked variations in the strength of attraction to a pheromone source according to time of day. There was a continuous decrease in sexual activity from morning to evening. Our findings reveal clear maturation periods for adult males of the seven studied species. The long immature phase of the adult male mealybug is probably also related to several physiological processes that are needed to complete male maturation. The most noticeable change is the elongation of the waxy caudal filaments. However, mating may be performed at any time ambient conditions are suitable. Whereas male mealybug flight towards a pheromone source is restricted to a few hours, the male may continue mating activity throughout its sexually active period.