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.

Data on the laxonomic composition of the arboreal arthropod fauna of 10 Bornean lowland rain forest trees are presented, based on samples obtained using insecticide fogging. Combined samples from all trees comprised 23,874 individuals of at least 3000 species. The mean number of species on each tree was 616.7 with one tree sample containing more than 1007 species. The relative rank of the major orders of arthropods in terms of both species and individuals was remarkably constant across the trees. Hymenoptera, Coleoptera, Diptera and Hemiptcra were the orders with the most species and individuals. Formicidae, though not particularly species rich, was the most abundant family in terms of individuals and the commonest species in six of the 10 trees was an ant. Refogging of one of the trees 10 days after initial sampling showed that the arthropod fauna had not completely recovered. What many arthropods are doing in the canopy is discussed.

The density of arboreal arthropods in a dry evergreen forest in Northeastern Thailand was investigated by the insecticide fogging (knockdown) method. Arthropod densities of 256.4 and 140.4 m-2 were recorded in the dry season and 195.2 and 123.1 m-2 in the rainy season. The main orders were Collembola, Thysanoptera, Hymenoptera (mainly Formicidae) and Hemiptera. Distinct differences were not found in the arthropod faunal structure and density between the dry and rainy seasons. However, this fauna is completely eliminated by the clearing and burning of forest for shifting cultivation.

The results of an experiment investigating the rate of arthropod fall after application of insecticide are presented and problems concerning the efficiency of the estimation methods used in this study are discussed.