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Title: Efficiency and establishment of three introduced parasitoids of the mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae)

item Epsky, Nancy

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2009
Publication Date: 10/1/2009
Citation: Amarasekare, K., Mannion, C.M., Epsky, N.D. 2009. Efficiency and establishment of three introduced parasitoids of the mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae). Biological Control. 51:91-95.

Interpretive Summary: The papaya mealybug is a threat to numerous agricultural products in the US. Three parasitoid wasps were introduced into south Florida in 2003 as biological control agents for this pest. However, there is little information on their establishment in areas in which they have been released and their effectiveness in controlling mealybug populations. Therefore, research was conducted by scientists SHRS in collaboration with scientists at the University of Florida to confirm establishment of these parasitoids to assess the efficacy for papaya mealybug control in the field. Two of the three parasitoid species were recovered from parasitized mealybugs. Over 30% of the sampled mealybugs were parasitized by other two species, with ~94% due to the parasitoid Acerophagus papayae. This is the first report of establishment of two of the three parasitoid species and shows that both species are adding to the biological control of the papaya mealybug. These results will be used by scientists, pest control operators and regulatory agencies to understand further the biological control potential for these parasitoid wasps, and to optimize their use for population suppression of this pest.

Technical Abstract: A study on the efficiency and establishment of three previously introduced parasitoids (Acerophagus papayae, Anagyrus loecki, and Pseudleptomastix mexicana) to control the mealybug Paracoccus marginatus was made in 2005 and 2006, at three locations in Homestead (Miami-Dade County), Florida. In each location, the number of mealybugs and natural enemies was monitored in closed, open, and no-cage environments on ten hibiscus (Hibiscus rosa-sinensis L.) plants. Mealybug populations were initially established on three branches of each hibiscus plant inside closed-sleeve cages. The treatments (closed-sleeve cage, open-sleeve cage, and no cage) were applied to the three established mealybug populations on each plant. After 72 h, the number of P. marginatus in the open-sleeve cage was higher than in the no-cage treatment but both were lower than the number in the closed-sleeve cage. There was no presence of natural enemies in the closed-sleeve cage treatment. Numbers of larvae and adult Cryptolaemus montrouzieri, ants, and spiders were higher in the no-cage treatment than in the open-sleeve cage. Two of the three parasitoids previously released for the biological control of P. marginatus in Florida were recovered in this study. Acerophagus papayae had a higher percent parasitism than A. loecki in both the open-sleeve cage (31.0 vs 2.3%) and the no-cage treatments (21.4 vs 1.6%) and caused the most mortality of P. marginatus. There was no recovery of P. mexicana in either of the treatments. Cryptolaemus montrouzieri may have contributed to the overall low parasitism. The low parasitism by A. loecki may be due to its multiple host preference.