Dataset includes - site information, assassin bug counts and rainfall measurements.

Research Project Data relates to a study that tested the effect of three alternative herbicide spraying regimes and associated vegetation complexity treatments on numbers of two species of assassin bugs (Cosmolestes picticeps and Sycanus dichotomus). The treatments encompassed a range of understory vegetation management practices used in oil palm plantations and include removing vegetation only in areas key to harvesting (“Normal”), removing all understory vegetation (“Reduced”), and allowing native vegetation to regrow naturally (“Enhanced”). Both the long-term (18 months) and short-term (within 2 weeks) effects of treatments were assessed following herbicide spraying.

Study Site Data was collected in industrial oil palm plantations in Riau Province, Sumatra, Indonesia (N0 55.559, E101 11.619). The region has a wet tropical climate, with an average annual rainfall of 2,350 mm. Data was collected across two neighbouring plantation estates (Ujung Tanjung and Kandista). These estates were planted between 1988 and 1993, meaning oil palms were mature (aged 20 – 27 years) at the time of data collection in 2013, 2014 & 2015. Across the two estates, oil palms were planted in staggered rows at a density of 136 palms/ha, or approximately 8 m apart. Project sites consisted of eighteen plots, arranged into six triplets. Each plot measured 150 × 150 m and was made up of a central 50 × 50 m core section and an outer buffer region. The three plots within each of the six triplets were randomly allocated to one of three understory treatments.

Collection Methods Adult assassin bugs (Reduviidae) of the species Cosmolestes picticeps and Sycanus dichotomus were surveyed along transects in the core of each study plot. Transect walks consisted of a recorder walking at a steady pace, counting any adult C. picticeps or S. dichotomus that were visible or flew up in front of the recorder (without deliberately disturbing vegetation) within a 5-m-sided cube of space in front of them. The transect was 200 m in length and followed the edge of the central 50 x 50 m core section within each plot. Transects were walked between 9:00 and 17:00 and were not conducted when it was raining.