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Title: Seasonal abundance, life history, and parasitism of Caloptilia porphyretica Braun (Lepidotpera: Gracillariidae), a leafminer of highbush blueberry

item Zhang, Aijun

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2009
Publication Date: 4/15/2010
Citation: Barry, J., Rodriquez-Saona, C., Polk, D., Zhang, A. 2010. Seasonal abundance, life history, and parasitism of Caloptilia porphyretica Braun (Lepidotpera: Gracillariidae), a leafminer of highbush blueberry. Journal of Economic Entomology. 103(2):284-291.

Interpretive Summary: The blueberry leafminer has become a regular occurrence in commercial high-bush blueberries grown in New Jersey. As high as 40-50% leaves with mines have been observed in many locations in New Jersey. Although blueberry bushes can tolerate leaf mining to some extent without loss of production, severe infestations may affect the general vigor and cause yield loss. A blueberry leafminer sex attractant was identified. By using the sex attractant to lure the insects into the trap, we were able to study the population changes of leafminer. In this study, we confirmed that at least three distinct generations existed per year. However, we found that the populations reached the highest peak in the second generation. This research information will be used by growers to efficiently apply insecticide in a timely manner. The information will also be used by researchers to future develop mating disruption and attract-and-kill technologies to manage blueberry leafminer populations in integrated pest management system for blueberry.

Technical Abstract: The leafminer, Caloptilia porphyretica Braun (Lepidoptera: Gracillariidae), has become a frequent pest in commercial highbush blueberries (Vaccinium corymbosum L.) in New Jersey; still, little information exists on its seasonal abundance, life history, and parasitism rates. Field monitoring programs were conducted from 2003-2006 in seven commercial blueberry farms to determine the relative abundance of this leafminer using pheromone-baited traps, cluster sampling (vegetative and flower/fruit clusters), and new shoot growth sampling. We found at least three distinct generations a year, with populations reaching the highest peak in the second generation. Additional laboratory studies characterized the life history of C. porphyretica and its parasitoid Pholetesor sp. The developmental period, from egg to adult, took 1221, 1037, and 1086 degree days (DD) at 20, 25, and 30ºC, respectively. This was equivalent to an average of 1115 DD to complete development to adult, which compared to 1282 and 1044 DD between the first and second, and second and third generations, respectively, using pheromone traps. Although C. porphyretica populations varied greatly from year to year, the number of larvae in cluster and new-growth samples was highly correlated with the number of adults in traps. Field parasitism rate was ~ 29%, with the predominant parasitoid being the braconid Pholetesor sp. prob. salalicus (Mason); however, 10 of the 13 species parasitizing this leafminer were from the family Eulophidae. After exposing different ages of leafminers to Pholetesor sp., it was demonstrated that this parasitoid attacks 9-15 d-old, early instars that reside in the mines of leaves.