Field assessment of two encyrtid parasitoids of Planococcus minor (Maskell) in Trinidad

Planococcus minor (Maskell) is widely established throughout the Neotropics, but little information is available regarding its pest status and natural enemies. This mealybug is one of the most likely species to be introduced into the continental US, and is therefore considered a high priority pest. Leptomastix dactylopii Howard and Coccidoxenoides perminutus Girault (Hymenoptera: Encyrtidae) were recently recovered from P. minor. These species have been used extensively to control other Planococcus spp. and are commercially available. However, no detailed studies have been done to assess their potential to control P. minor. Preliminary surveys suggest that these parasitoids might be effective in suppressing mealybug populations. The occurrence of seemingly specialist natural enemies attacking the mealybug on the island is interesting and this field study was set up with the objective of assessing their potential for controlling this pest. Potatoes separately infested with mealybugs comprising three stages (adult females, 3rd instar nymphs, and 2nd instar nymphs) were deployed at 5-day intervals once monthly from April 2008 to March 2009 to determine stage specific percent parasitism. This information is the first step in determining whether these species are effective parasitoids, persisting throughout the sampling season, and therefore are suitable candidates for biological control of P. minor.