Integrated pest management (IPM) is widely practiced in commercial oil palm agriculture. This management system is intended to minimize the number of attacks by pest insects such as bagworms on crops, as well as curb economic loss with less dependency on chemical pesticides. One practice in IPM is the use of biological control agents such as predatory insects. In this study, we assessed the response of predatory natural enemies to pest outbreak and water stress, and document the habitat associations of potential pest predators. The abundances of 2 predatory insect species, namely Sycanus dichotomus and Cosmolestes picticeps (Hemiptera: Reduviidae), were compared bagworm outbreak sites and nonoutbreak sites within oil palm plantations. We also examined habitat characteristics that influence the abundances of both predatory species. We found that the abundance of C. picticeps was significantly higher in bagworm outbreak sites than in nonoutbreak sites. There were no significant differences in the abundance of S. dichotomus among outbreak and non-outbreak sites. Both species responded negatively to water stress in oil palm plantations. Concerning the relationship between predatory insect abundance and in situ habitat quality characteristics, our models explained 46.36% of variation for C. picticeps and 23.17% of variation for S. dichotomus. Both species of predatory insects thrived from the planting of multiple beneficial plants in oil palm plantations. The results suggest that C. picticeps can be used as a biological agent to control bagworm populations in oil palm plantations, but S. dichotomus has no or little potential for such ecosystem service.
This paper presents a taxonomic revision of 28 described species of the genus Sirthenea Spinola, 1837 (Hemiptera: Heteroptera: Reduviidae: Peiratinae) distributed in the Afrotropical, Oriental, Palearctic, Oceanian and Australian zoogeographical regions. The following new synonymies are proposed: Sirthenea africana Distant, 1903 = S. rapax Horváth, 1909, syn. nov. = S. leonina Horváth, 1909, syn. nov. = S. bequaerti Schouteden, 1913, syn. nov. = S. leontovitchi Schouteden, 1931, syn. nov.; Sirthenea picescens Reuter, 1887 = S. atrocyanea Horváth, 1909, syn. nov.; S. rodhaini Schouteden, 1913 = S. collarti Schouteden, 1931, syn. nov. = S. angolana Villiers, 1958, syn. nov.; S. flavipes (Stål, 1855) = S. clavata Miller, 1948, syn. nov. = S. bharati Sucheta Chopra, 1988, syn. nov. = S. koreana Kerzhner Lee, 1996 syn. nov. = S. melanota Cai Lu, 1990, syn. nov. = S. nigripes Murugan Livingstone, 1990, syn. nov.; S. obscura (Stål, 1866) = S. glabra (Walker, 1873), syn. nov. A neotype is designated for S. picescens Reuter, 1887. Three species, S. erythromelas (Walker 1873), S. fulvipennis (Walker, 1873) and S. sobria (Walker, 1873), are excluded from the genus Sirthenea. Two new species from the Oriental Region, S. kali sp. nov. (India) and S. setosa sp. nov. (Malaysia) are described. Identification keys are provided for the subgenera and species from each zoogeographical region treated. Drawings of dorsal habitus and genitalic structures, drawings and images of selected morphological characters, and distribution maps of all valid species are presented.
A new cavernicolous, arachnophilous thread-legged bug (Phasmatocoris labyrinthicus sp. nov.; Reduviidae: Emesini) is described from Kartchner Caverns, a limestone cavern in Kartchner Caverns State Park near Benson, Arizona, USA. Cavernicolous emesines are recorded from caves in many parts of the world and are distributed across several genera, but are generally uncommon. P. labyrinthicus shows no obvious troglomorphy but ecological evidence suggests it is, at minimum, a cave-limited troglophile. The species seems to be low-humidity intolerant, due to its occurrence in a cave within a desert region, effectively confines the population to the cave, and the species may thus actually be troglobitic by default. Arachnophily in emesines is more common, including in Phasmatocoris Breddin, but has been previously documented in only a single cavernicolous species, Bagauda cavernicola Paiva, reported from India, Malaysia and Sri Lanka. However, unlike P. labyrinthicus, B. cavernicola is apparently not morphologically adapted for its arachnophilous association. P. labyrinthicus is the only known troglophilic emesine that is also a morphologically adapted and behaviorally functional arachnophile. The only other known cavernicolous Phasmatocoris (P. xavieri Gil-Santana, Alves, Barrett and Costa) is recorded from a sandstone cave in Brazil. P. xavieri exhibits morphological features indicative of a potentially arachnophilous habit, but its ecology has not been studied. Adults of P. labyrinthicus share characteristics with the species Phasmatocoris praecellens Bergroth, P. minor McAtee and Malloch, P. xavieri, P. spectrum Breddin, and P. rapax McAtee and Malloch. Phasmatocoris is primarily a Neotropical genus and the discovery of P. labyrinthicus represents a significant range extension for the genus, being the first Nearctic species identified, with its geographically nearest relative an undescribed species from Mazatlan, Mexico, over 1,000 km to the south.
Matched MeSH terms: Reduviidae/anatomy & histology; Reduviidae/classification*; Reduviidae/growth & development
Kajian untuk memelihara Sycanus dichotomus Stal. (Hemiptera: Reduviidae), serangga pemangsa ulat bungkus tanaman sawit, Metisa plana Walker (Lepidoptera: Psychidae) dengan menggunakan larva dua spesies serangga, Corcyra cephalonica Stainton (Lepidoptera: Pyralidae) dan Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae) telah dilakukan di makmal. Kemandirian hidup (%), bilangan telur yang menetas dan tempoh (hari) perkembangan pemangsa (lima peringkat nimfa) telah direkodkan. Min tempoh perkembangan pemangsa peringkat nimfa pertama hingga kelima pemangsa apabila diberi makan larva C. cephalonica masing-masingnya adalah 15.16, 12.09, 11.63, 14.25 dan 18.53 hari, manakala 15.21, 12.34, 12.64, 14.84 dan 21.89 hari apabila diberi makan T. molitor. Min masa perkembangan dari peringkat telur hingga dewasa S. dichotomus apabila diberi makan larva T. molitor adalah lebih lama (156.5 hari) dan berbeza secara bererti (t = 6.51; dk = 87; p < 0.05) berbanding apabila diberi makan dengan larva C. cephalonica (122.8 hari). Peratus kemandirian hidup S. dichotomus daripada peringkat nimfa pertama hingga dewasa adalah lebih tinggi (81%) apabila diberi larva T. molitor berbanding larva C. cephalonica (76%) sebagai makanan. Julat bilangan telur yang menetas apabila diberi makan larva T. molitor adalah antara 46.6 hingga 77.6 ekor. Keputusan menunjukkan S. dichotomus boleh dipelihara dengan menggunakan larva T. molitor sebagai makanan. Keputusan kajian ini juga diharapkan menjadi titik tolak permulaan penyelidikan seterusnya di dalam bidang hubungan mangsa-pemangsa bagi program kawalan biologi di ladang sawit.