Samson Laup

Activity of male pheromone of Melanesian rhinoceros beetle Scapanes australis

Laboratory and field investigations were carried out to investigate the nature and role of the male pheromone emitted by the Dynast beetle Scapanes australis and to develop a mass trapping technique against this major coconut pest in Papua New Guinea. We report the biological data obtained from natural and synthetic pheromone, previously described as an 84:12:4 (w/w) mixture of 2-butanol (1), 3-hydoxy-2-butanone (2), and 2,3-butanediol (3). EAG recordings from natural and synthetic pheromone and a pitfall olfactometer were poorly informative. In contrast, extensive field trapping trials with various synthetic pheromone mixtures and doses showed that 1 and 2 (formulated in polyethylene sachets in 90:5 v:v ratio) were necessary and sufficient for optimum long-range attraction. Beetles were captured in traps baited with racemic 1 plus 2, with or without a stereoisomer mixture of 3 (2.5- to 2500-mg/day doses). Plant pieces, either sugarcane or coconut, enhanced captures by the synthetic pheromone, which was active alone. Traps with the pheromone caught both sexes in a 3:2 female–male ratio. A pheromone-based mass trapping led to the capture of 2173 beetles in 14 traps surrounding 40 ha of a cocoa-coconut plantation. The captures followed a log-linear decrease during the 125-week trapping program. The role of the male pheromone and its potential for crop protection are discussed.

Conopomorpha cramerella (Lepidoptera: Gracillariidae) in the Malay Archipelago: Genetic Signature of a Bottlenecked Population?

Abstract Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillariidae) is a devastating pest of cacao, Theobroma cacao L. (Sterculiaceae), in Southeast Asia, particularly in the Malay Archipelago. We surveyed genetic variation at two unlinked loci, mitochondrial cytochrome oxidase I (COI) and nuclear elongation factor-1α (EF-1α), in C. cramerella from throughout most of their known geographic range. Given the enormous area sampled, COI variation is extremely low; EF-1α variation may be low as well, but this is more difficult to assess due to the lack of appropriate data sets for comparison. Our results strongly suggest that sampled C. cramerella populations have experienced at least one bottleneck in their recent past, although the possibility that COI variation has been reduced by a selective sweep cannot be excluded based on available data. We suggest that one or more bottlenecks likely occurred when C. cramerella from an as yet unknown source population, either within or outside the Malay Archipelago, became established on cacao, which is not endemic to this region (Conopomorpha is an Old World genus and cacao originated in the New World). Identification of the source of this pest could be important in efforts to identify natural enemies for biological control.

Simplified Field Key to Identify Larvae of Some Rhinoceros Beetles and Associated Scarabs (Coleoptera: Scarabaeoidea) in Papua New Guinea Coconut Developments

Abstract In Papua New Guinea, Coleoptera associated with coconuts share or have similar larval breeding sites, which has led to some confusion with their identity. Conclusive identification of these larvae is important before deciding whether it is possible to use biological control measures against them. The available keys are complex and do not take into account simple observable characters that can be used in the field with live specimens. Specimens of the following species were examined: Xylotrupes gideon (L.), Trichogomphus vicinus Dechambre, Oryctoderus latitarsis Boisduval, Oryctes centaurus Sternberg, Oryctes rhinoceros (L.), Scapanes australis Boisduval (Coleoptera, Scarabaeidae, Dynastinae), Dermolepida sp. (Coleoptera, Scarabaeidae, Melolonthinae), Cetoniinae (Coleoptera, Scarabaeidae) and Lucanidae (Coleoptera Scarabaeoidea). A simple key to distinguish 2 important pest species, O. rhinoceros and S. australis, from allied Coleoptera directly in the field is presented, together with drawings and photographs to illustrate distinctive features to assist in using the key. The identifications presented in the paper were checked against existing taxonomic keys.