Plant Protection Quarterly Vol.24(1) 2009 27 (Merr.) Fosberg (Cucurbitaceae), an en- demic plant in Guam and Rota, and the Life-history, host preference and establishment introduction and establishment of M. oedi- status of Melittia oedipus (Lepidoptera: Sesiidae), pus in Guam and Saipan. The aim of this study is to obtain more precise estimates a biological control agent for Coccinia grandis and predict performance or generation (Cucurbitaceae) in the Mariana Islands times in the new range of M. oedipus. Materials and methods A A B G.V.P. Reddy , Z.T. Cruz and R. Muniappan All the laboratory studies were conducted A Agricultural Experiment Station, College of Natural and Applied Sciences, at the Western Pacifi c Biocontrol Quaran- University of Guam, Mangilao, Guam 96923, USA. tine Laboratory (WPBQL) of the Univer- B IPM CRSP, OIRED, Virginia Tech, 526 Prices Fork Road, Blacksburg, VA sity of Guam. 24061, USA. Importation of M. oedipus and laboratory conditions About 200 C. grandis cuttings (~20 cm long × 4–5 cm diameter) with immature stages Summary but it has become invasive in lowland of M. oedipus were brought from Kona Ivy gourd or scarlet gourd, Coccinia gran- areas of the Hawaiian Islands (Linney (Hawaii) to Guam and reared at the WP- dis (Violales: Cucurbitaceae), is a peren- 1986, Telford 1990, Chun 2001). This per- BQL. The controlled environmental condi- nial vine and a native of Africa that has ennial vine grows best under conditions tions in the quarantine room were main- invaded lowland areas of the Hawaiian of moderate rainfall and high humidity tained at a 12:12 L:D photoperiod, with a and Mariana Islands. Failure of mechani- (Muniappan et al. in press). Accidental mean day and night temperature of 32 and cal or chemical control techniques to sup- introduction of this vine into Guam and 17°C , respectively, and a relative humid- press this weed led to the initiation of a Saipan in the 1980s resulted in the inva- ity of 65–80%. The quarantine room was biological control program in the Mari- sion of over 100 hectares in different parts illuminated with two plant growth lights ana Islands (Guam, Saipan, Rota and Ti- of Guam and almost 14 000 hectares in (Gualala Robotics Inc. Denver, Colorado) nian). This follows the success achieved Saipan (Raman et al. 2006, Bamba 2008). It controlled by automated timers. in Hawaii by introducing the natural en- is also invading the neighbouring islands emies, Acythopeus cocciniae (Coleoptera: of Rota and Tinian (USDA 2003, 2004). Insect rearing Curculionidae), Acythopeus burkharto- Mechanical and chemical control meth- From the stock of 200 cuttings which con- rum (Coleoptera: Curculionidae) and ods have not proven effective, feasible or tained various immature stages of M. oedi- Melittia oedipus (Lepidoptera: Sesiidae). sustainable in the Mariana and Hawaiian pus, 20 cuttings were selected and placed Of these three biological control agents, Islands (Motooka et al. 2002, Muniappan in 10 identical plastic containers each 45 M. oedipus has proven to be effective in et al. in press). A biological control pro- cm long × 30 cm wide × 15 cm depth and suppressing C. grandis in Hawaii. gram was initiated in the Mariana Islands sealed with lids. Using a sharp blade, a 28 Life history of M. oedipus has been de- based on the success achieved in Hawaii cm × 13 cm incision made on the top of scribed. Females laid 144 eggs on average by introducing the natural enemies, Acy- the lid, which was covered with muslin during their lifetime. The mean duration thopeus cocciniae O’Brien and Pakaluk cloth and sealed with glue to allow aera- of the egg, larval and pupal stages were (Coleoptera: Curculionidae), Acythopeus tion. Subsequently, C. grandis vines about 9.4, 43.5 and 21.4 days, respectively. Fe- burkhartorum O’Brien and Pakaluk (Cole- 4–5 cm diameter were harvested from the males lived longer than the males with optera: Curculionidae) and Melittia oedipus fi eld and brought to the laboratory where a mean of 4.5 days and 3.4 days, respec- Oberthür (Lepidoptera: Sesiidae) (Reddy they were rinsed with a 10:1 (v:v) water/ tively. This study indicated that M. oed- and Muniappan 2005). Acythopeus cocciniae Clorox® (bleach) solution and dried off ipus is specifi c to C. grandis and larval grubs mine the leaves causing defoliation, with paper towels. Care was taken to avoid development did not occur on Zehneria A. burkhartorum grubs induce stem and any vines that might have been exposed to guamensis (Cucurbitaceae), an endemic petiole galls, and M. oedipus caterpillars herbicides or insecticides. Vines were cut plant of Guam and Rota. Field release burrow through the larger stems and oc- into pieces measuring 15 to 17 cm in length of M. oedipus in the Marianas resulted casionally the roots causing the vines to and eight to 20 pieces were placed in the in establishment in Guam and Saipan, wither (Chun 2001). Chun’s (2001) host containers atop the old cuttings so that the however the presence of pavement ant specifi city tests confi rmed that M. oedipus larvae could migrate to them as the old Tetramorium bicarinatum (Nylander) is monophagous and specifi c to C. grandis. cuttings deteriorated. This was essential in (Hymenoptera: Formicidae) on vines in In larval feeding tests, a few reached adult raising a successful culture. Olfactory cues the fi eld in Saipan has hindered estab- stage on cucumber (Cucumis sativus L. Cu- given off by the freshly cut vines stimu- lishment there. curbitaceae) vines but no further develop- lated the larvae to migrate to the newer Keywords: Melittia oedipus, Sesiidae, ment was observed. However, choice-tests cuttings and continue feeding. Coccinia grandis, Zehneria guamensis, for oviposition revealed that under fi eld When the cuttings had rotted, they Cucurbitaceae, life-history, host prefer- conditions, M. oedipus females would be were gently peeled apart and the pupae ence, Mariana Islands. highly unlikely to lay eggs on C. sativus. formed in them were removed. Weekly Since 1996, when M. oedipus was released collections of the rotten vine cuttings Introduction in the Hawaiian Islands, there has been no were placed in a double plastic garbage Ivy gourd or scarlet gourd, Coccinia gran- record of attack on C. sativus or any other bags and incinerated at the Guam Refi n- dis (L.) Voigt (Violales: Cucurbitaceae), a non-target plant (Chun 2001). ery and Environmental Services Company native of East Africa is widely distributed Chun (2001) carried out some prelimi- (GRESCO). The collected pupae were then in the Indo-Malayan region (Singh 1990). nary studies on the life history of M. oedi- placed in plastic boxes 14 cm long × 9.5 It has also become naturalized in parts pus. In this paper, we present details of the cm wide × 10 cm height until the adults of Australia, the Caribbean, the southern life history of M. oedipus, a host-specifi ci- emerged. Each box had an opening (8 cm United States, and several Pacifi c Islands ty test conducted on Zehneria guamensis × 4 cm) on the lid which was covered with 28 Plant Protection Quarterly Vol.24(1) 2009 muslin cloth and sealed with glue for aera- and life history under the laboratory Host preference studies tion purposes. Upon emergence from the conditions in Guam, and compared with The host specifi city tests on M. oedipus were pupa, new adults (<1 day old) were re- studies by Chun et al. (2001) carried out conducted at WPBQL of the University of leased into a cage with dimensions 91.4 in Hawaii. Guam (USDA 2007). Chun (2001) has al- cm wide × 45.7 cm deep × 63.5 cm tall. The ready carried out host specifi city tests on base of the cage was aluminium, while the Oviposition rate by M. oedipus several species of plants in the Cucurbita- top and back side was of Plexiglas which Three to six female and six to 12 newly ceae family and closely related ones using permitted light into the cage (light, par- emerged male moths were released into a the centrifugal phylogenic method recom- ticularly natural sunlight stimulates mat- cage (measuring 91.4 cm wide × 45.7 cm mended by Wapshere (1974). In consulta- ing and oviposition). The front door had deep × 63.5 cm tall) containing a single tions with the University of Guam, Guam two sleeves (of cheese cloth material) for potted C. grandis plant to ensure mating. Department of Agriculture, Department of release of new moths, collection of dead Moths were fed with a 1:1 (v:v) honey/wa- Land and Natural Resources of the North- ones and for feeding the moths. The other ter solution and left undisturbed for a 24 ern Marianas, the U.S. Fish and Wildlife two sides of the cage were covered and h period to allow for oviposition. Artifi cial Service, and APHIS, it was decided that sealed with muslin cloth for aeration. A C. sunlight, necessary to stimulate mating, the endemic species, Zehneria guamensis grandis plant was potted in a 3 L contain- was emitted via a mobile sun lamp which (Merr.) Fosberg (Cucurbitaceae), should er and placed inside the cage to emulate was maintained at a 12:12 L:D photope- be one of the candidates in a host spe- natural conditions as well as to allow for riod. After 24 h, the moths were removed cifi city test since it belongs to the same oviposition by the gravid females. and released into a separate cage and the family as C. grandis and is the only cucur- While adult male and female M. oedi- eggs collected, counted and recorded. Ad- bit species endemic to the region (Stone pus are similar in appearance, they can be ditionally, eggs were measured under a 1970).