Objectives To describe wasp and bee species that sting humans, analyse risk factors and clinical features.

Dengue vector control programmes are mainly focused on insecticide fogging/space spraying to control adult Aedes mosquito vector populations. Due to the diurnal habit of the vectors, spraying is routinely conducted during the day when many other insect species are also active. This study reports the simultaneous effect of fogging on non-target insects by direct counting of knockdown in the insect population. Eight fogging treatments were conducted in two sites in Kurunegala District of Sri Lanka. Pesguard insecticide was sprayed in each treatment for 8 minutes according to the standard methodology and the ‘knockdown insects’ were collected on randomly spread polyethythene sheets (10 m2). A total of 3884 insects (24.3 insects per treatment per m2) belonging to 12 orders were collected and 12.44% of them recovered during a 24-hr recovery period. Diptera was the most affected insect order (36%) followed by Collembola (30%) and Thysanoptera (17%). Out of the 31 mosquitoes (<1%) collected, only two (<0.1%) belonged to the genus Aedes. Body length of 93% of the affected insects ranged from 0.35 mm to 1.8 mm. Positive controls using the WHO standard cage bioassays with the mosquito Ae. albopictus (n = 417) and the stingless bee Trigona iridipennis (n = 122) showed 100% initial knockdown, and 83.5% mosquito and 93.5% bee mortalities after the recovery period. The study shows that insecticide fogging does have a severe effect on non-target insects such as pollinators; therefore, fogging operations should be done in a controlled manner and indiscriminate fogging should be avoided.

Studies to evaluate consequences of native species showing invasive behaviour are rather scarce in the tropics. Bambusa bambos (L.) Voss., a native bamboo species, expands populations in its native range causing changes to the appearance of forests in dry and intermediate zones of Sri Lanka. The study evaluated the impacts of B. bambos spread in Tropical Moist Evergreen Forests (TMEFs) in Sri Lanka. A vegetation study was carried out in forest patches with and without bamboo (B+ and B-) from three study sites viz., Galboda (GAL), Moragolla (MOR) and Maragomuwa (MAR) located in the Intermediate Zone of the island. Six 100 m 2 quadrats were eramarked at different distances from the forest edge towards the forest interior along three transects in each B+ and B-forest communities per site totaling 108 quadrats (2 forest communities B+ and B-× 3 transects × 6 distances × 3 sites = 108). Due to high site-specific differences, the results were analyzed and presented site-wise. Of the total of 127 species, 35 (27.6%) and 20 (15.7%) species were exclusively found in B+ and B-, respectively. The endemics were constantly more abundant in bamboo-free forest patches. The analyses also revealed a high dissimilarity of species compositions between B+ and B-forest communities. The mortality incidences were significantly greater in bamboo-forests, possibly due to frequent fires aided by high accumulation of light bamboo litter. Despite no consistent differences between B+ and B-communities in all study sites due to high heterogeneity, the results indicate that B. bambos has shown the potential to alter the composition and structure of these native forests through bamboo-driven modifications to micro-environmental conditions of these forests. Thus, the study highlights the importance of more comprehensive studies to explore long-term impacts of B. bambos in native forests in the region and to introduce measures to mitigate some of these negative impacts. The underlying causes of high mortality incidences should also be further investigated as it may leads to the decline of the quality of these native forests.

No abstract

This study compares the termite assemblages in a natural and a secondary forest located at two different elevations in the Hantane hills, a tropical evergreen forest in mid country Sri Lanka, with a view to identify their distinctiveness. To sample the termites in the two forest types the belt transect method was used supplemented by random collections. A total of 11 species of termites in four genera belonging to three subfamilies and one family, Termitidae were recorded; nine species from the secondary forest and two species from the natural forest. The two species, Ceylonitermellus hantanae and Dicuspiditermes incola showed a distinct distribution in being confined only to the natural forest at high elevation. Termites recorded were put into feeding groups based on their taxonomic identity. Termites of the natural forest were found to be exclusively true soil feeders. Those of the secondary forest were wood feeders; either fungus growing (8 spp.) or non-fungus growing wood feeders (1 sp.). The high abundance and low diversity of the natural forest termite species in comparison to secondary forest species also make them distinct. Elevation, climate, vegetation, ground cover and the degree of human interference appear to contribute to the distinctiveness of termite assemblages in the two forests types reported here.

Considering the environmental and specific socioeconomic significance of the critically endangered mangrove Lumnitzera littorea, this study was conducted aiming the conservation of the species. The specific objectives were to define the diversity of the other mangrove species in association with the existing L. littorea plant population in the Madu Ganga wetland, Sri Lanka, to study its seed germination and identify the barriers for seed germination. The existing population of L. littorea is an aged population with low regeneration potential. Most of the seeds collected at the dispersal maturity were empty. A micro moth belonging to Family Gelechiidae was identified as the embryo predator. Although GA3 (Gibberellic acid) treatment and dry storage reduced the germination time, none of the seed treatments significantly improved the seed germination of L. littorea. Low seed germination observed was due to absence of embryo in mature seeds as a result of insect predation and physiological dormancy of seeds. Optimum GA3 concentration, duration of dry storage and potting medium with suitable salt concentration for seedlings should be optimized in future research.

This study was conducted in the Knuckles Forest Region in central Sri Lanka, and investigated how termite species richness, abundance and functional group diversity vary in different montane forest types and identified the likely causes of this pattern. Termite diversity declined with increased elevation, with upper montane forests recording a single endemic species, Postelectrotermes militaris Desneux. Transect sampling in lower montane forests yielded 26 species, with a higher number from dry forests (22 species) than from wet forests (15 species). Species specificity also was high in dry forests (11 species) compared with wet forests (four species). Termite abundance did not show a distinct trend in dry and wet forests. Live-wood termites were present only in upper montane and high-altitude lower montane dry forests. Wet forests had a higher relative abundance (78%) but not species richness (40%) of soil and soil -wood interface feeders. In dry forests, both species richness (82%) and abundance (88%) of fungus-growing wood feeders were higher. The study suggests that key drivers of the species distribution pattern are low temperature and differing forest floor conditions. In the upper montane forest floor where earthworms dominate, wet soil and damp, woody litter riddled with beetles are not favourable for termites. In lower montane wet forests, moist, thick decomposing leaf litter and in dry forests, drier, relatively undecomposed leaf litter with many dry sticks and branches support species with specific food habits.

In the order Hymenoptera, bees, hornets, and wasps are well-known stinging insects whose envenoming can be fatal. Their stinging attacks are common in rural and forested areas of Sri Lanka. However, fatal stinging by the large-bodied carpenter bees is unreported. We report the first known case of a fatal sting by the large carpenter bee, Xylocopa tranquebarica, in a forested area in Puttalam (North Western Province) in the dry zone of Sri Lanka. A 59-year-old healthy male manual laborer accompanied by a fellow worker had been fixing a fence on a coconut estate bordering a forested area when a flying insect emerged from a dead tree trunk and stung him on his face. His coworker, who was watching the incident, killed the insect. The victim complained of immediate intense pain in the face and collapsed on the ground just after resuming work after 10 minutes of resting. He was found dead on admission to the hospital 90 minutes later. Autopsy showed normal coronary arteries and heart, but the lungs were slightly congested and contained secretions in the bronchi. Acute anaphylaxis was the most likely cause of death. This case presents the habitat, morphology, attack pattern, and the medical importance of large carpenter bees.