Evaluating the Performance and Preference of Aphytis melinus (Hymenoptera: Aphelinidae) on an Exotic Species, Acutaspis albopicta (Hemiptera: Diaspididae), and Aonidiella aurantii (Hemiptera: Diaspididae).

Acutaspis albopicta (Cockerell) is an exotic scale detected on imported 'Hass' avocados arriving in California from Mexico. An effort was made to understand how well this species might be biologically controlled by the parasitoid, Aphytis melinus DeBach. In no-choice trials, single life stages of A. albopicta and Aonidiella aurantii (Maskell) were exposed to one Ap. melinus female. Ap. melinus attacked and developed to adult on all A. albopicta life stages tested, which included early, middle, and late male and female second instars, and early, middle, and late female third instars. However, the proportion of scales attacked was relatively low (≤20%), as were the number of eggs laid on each scale stage. In six of seven comparisons of scale cover surface area between A. albopicta and Ao. aurantii that were similarly aged, Ao. aurantii was significantly larger. With intraspecific choice trials, females of Ap. melinus strongly preferred to parasitize the oldest and largest female scales in both single- and mixed-sex offerings. Younger, smaller scales were preferred for host feeding. Five comparisons of preference between A. albopicta and Ao. aurantii showed that Ap. melinus preferred 28- and 36-d-old Ao. aurantii females over similarly aged A. albopicta. However, Ap. melinus preferred 23-d-old males of A. albopicta. In three of five comparisons, Ao. aurantii was the preferred species to host feed on. More F1 females of Ap. melinus were recovered from both intraspecific choice trials compared with any stage in no-choice trials. Implications of incorporating Ap. melinus into biological control programs are discussed.

First record of Closteroceruschamaeleon, parasitoid of the Eucalyptus Gall Wasp Ophelimusmaskelli (Hymenoptera, Chalcidoidea, Eulophidae), in the New World.

The uniparental parasitoid Closteroceruschamaeleon (Girault) is discovered to be fortuitously present on a population of the invasive Eucalyptus Gall Wasp Ophelimusmaskelli (Ashmead) in Riverside, California. This is the first report from the New World of Closteroceruschamaeleon, which has proven to be a highly effective natural enemy of Ophelimusmaskelli in the Mediterranean Basin. The taxonomy and identification of Closteroceruschamaeleon is discussed.

Syntheses and determination of absolute configurations and biological activities of the enantiomers of the longtailed mealybug pheromone.

Preparation and assignment of absolute configurations to both enantiomers of the sex pheromone of the longtailed mealybug, an irregular monoterpenoid with extraordinary biological activity, has been completed. Comparison of the biological activities of both enantiomers and the racemate in field trials showed that the (S)-(+)-enantiomer was highly attractive to male mealybugs, strongly suggesting that female longtailed mealybugs produce this enantiomer. The (R)-(-)-enantiomer was benign, being neither attractive nor inhibitory.

Reproductive biology of Pseudococcus maritimus (Hemiptera: Pseudococcidae).

This study characterized several parameters associated with reproductive behaviors of a Californian population of the grape mealybug, Pseudococcus maritimus (Ehrhorn). Experiments with caged adults confirmed that females from this population could not reproduce parthenogenetically. Both sexes were capable of mating multiple times on the same day and on sequential days. Median times between copulations were short (< 10 min) on the first day that males were presented with females, but tended to increase with sequential copulation events. Unmated females lived for up to 19 wk, whereas mating and oviposition resulted in reduced longevity. We hypothesized that constant exposure to pheromone might stimulate males to leave their cocoons sooner and increase their activity levels compared with males that were not exposed to pheromone, resulting in shortened life-spans. However, whereas exposure to pheromone did stimulate males to emerge slightly sooner than control males, pheromone exposure had no effect on the longevity of males. The implications of the results of these experiments for pheromone-based methods of detection and control of mealybugs are discussed.

Developmental biology of an exotic scale, Acutaspis albopicta (Hemiptera: Diaspididae).

Acutaspis albopicta (Cockerell) is one of seven exotic scale species detected on shipments of'Hass' avocados entering California from Mexico. Here, we present the results of experiments to elucidate basic life history parameters of this species. The scale only reproduces sexually with unmated females producing no offspring. Unmated females survived up to 14 wk after settling on host fruits, whereas males survived for up to 62 h, with the majority dying within 46 h after emergence. Females laid a mean of 52.0 +/- 2.8 eggs (range, 5-171 eggs). Lower humidity (50%) was detrimental to the survival of male scales compared with high humidity (75%), especially during the pupal stage. The optimal temperature for development of both sexes was 25 degrees C. At this temperature, females developed from first instars to adults in approximately 28 d, whereas males emerged from their pupal cases after approximately 37 d. The adjusted lower developmental thresholds for females and males were 13.2 and 13.4 degrees C, respectively. The upper developmental threshold for both females and males was approximately 32 degrees C. Total development from first instar to adult female was 329 degree days and to emerged male, 433 degree days.

Pheromone-baited traps for assessment of seasonal activity and population densities of mealybug species (Hemiptera: Pseudococcidae) in nurseries producing ornamental plants.

Operational parameters of traps baited with the pheromones of three mealybug species were optimized in nurseries producing ornamental plants. All pheromone doses (1-320 microg) attracted Pseudococcus longispinus (Targioni Tozzetti) and Pseudococcus viburni (Signoret) males, with the lowest dose (1 microg) attracting the fewest males for both species. Doses of 3.2-100 microg were as attractive to male P. longispinus as the highest dose (320 microg); doses from 10 to 320 microg were equally attractive for P. viburni males. Lures containing 25-microg doses of either pheromone had effective field lifetimes of at least 12 wk. Experiments were performed to test the efficacy of combining multiple pheromones to attract several species of mealybugs simultaneously. Lures loaded with a mixture of the pheromones of P. longispinus, P. viburni, and Planococcus citri (Risso) were as attractive to P. viburni and P. citri as lures with their individual pheromones. Response of P. longispinus to the blend was decreased by 38% compared with its pheromone as a single component. A subsequent trial with two-component blends showed that the pheromone ofP. citri was responsible for this modest decrease in P. longispinus response. This should not affect the overall efficacy of using these lures for monitoring the presence of all three mealybug species simultaneously. Pheromone traps were used to detect infestations of P. longispinus throughout the season and to track population cycles. When pheromone-baited traps for P. longispinus were compared with manual sampling, trap counts of male mealybugs were significantly correlated with mealybugs counted on plants in the vicinity of the traps.