Improved BioGents® Sentinel trap with heat (BGSH) for outdoor collections of Anopheline species in Burkina Faso and Mali, West Africa

Background Since the late 1990s, malaria control programmes have relied extensively on mass bednet distribution and indoor residual spraying. Both interventions use pesticides and target mosquitoes coming indoors either to feed or to rest. Unfortunately, these intensified vector control campaigns have resulted in mosquito populations with high levels of resistance to most of the chemical compounds used against them and which are increasingly exophagic and exophillic, hence difficult to monitor indoors. Consequently, there is an urgent need for novel tools to sample outdoor anopheline populations for monitoring interventions and disease surveillance programmes. Methodologies In this study, we tested several modifications and configurations of the BioGents® Sentinel (BGS) trap, designed with the aim to increase its efficacy for sampling malaria vector species. Traps were used with chemical attractants and CO2, and the impacts of trap position, trap colour contrast combination and the addition of a heat source were tested in two studies conducted in the Sudano-Sahelian region of Burkina Faso and Mali. Results The results show that of all the configurations tested, the addition of a heat source to the BGS trap with the original colour combination and an upward positioning resulted in a 1.8- and 5.9-fold increase in host-seeking Anopheles gambiae (s.l.) females in the experiments performed in Burkina Faso and Mali, respectively. BGS with heat traps, referred to as BGSH traps, captured An. gambiae (s.l.), An. pharoensis, An. coustani, Culex and Mansonia spp. Importantly, the results suggest that their efficacy does not depend on the close proximity of nearby hosts in houses. Conclusions The results suggest that BGSH traps can be an effective scalable tool for sampling outdoor anopheline vector populations. Further developments enabling CO2 and heat generation for longer periods of time would further improve the trap’s versatility for large-scale surveillance programmes.

Population Abundance of Insect Trapped on Different Colours of Sticky Trap in Pumpkin (Cucurbita moschata) Field

A study was conducted to attract insects using different colours of sticky trap in pumpkin (Cucurbita moschata) field. Sticky trap was chosen as it is one of a method to estimate the insect population density in field as it requires a low cost and less skilled labour. Four different colours of sticky traps (i.e. red, white, blue and yellow) were used to determine the insect population abundance at the pumpkin field. All the traps were installed at the height of 100 cm at a random of 1 ha of pumpkin plot with five replicates for each colour and the insect samples were collected weekly for three months (October-December 2019). Overall, a total of 13,052 insects were collected throughout 11 weeks of sampling. The results showed that the percentage of insect population abundance recorded the highest was on week eight (15.01%) whilst the least abundance of insects trapped was on week one (2.28%). The most attractive colour to attract insects was significantly the yellow colour (44.34%) followed by blue (20.12%) and white (19.15%) whilst the lowest insect trapped was on red colour (16.40%). A total of nine insect orders recorded were; Diptera, Hemiptera, Coleoptera, Hymenoptera, Lepidoptera, Orthoptera, Blattodea, Isoptera and others. Diptera was the most abundant of insect’s order trapped in the yellow trap with 3427 individuals and followed by Hemiptera order (1022 individuals). Whilst the Isoptera order was the least number of insects caught on a red colour trap with only one individual. In conclusion, our findings showed that the yellow sticky trap colour is the most attractive to attract insects of C. moschata compared to other colours. Therefore, this study could provide essential knowledge that may be useful for the future ecological survey of insects of C. moschata.

Influence of trap colour, type, deployment height, and a host volatile on monitoring Orchestes fagi (Coleoptera: Curculionidae) in Nova Scotia, Canada

Orchestes fagi (Linnaeus) (Coleoptera: Curculionidae) is a pest of beech trees (Fagus sylvatica Linnaeus; Fagaceae) in Europe that has recently become established and invasive on American beech (Fagus grandifolia Ehrhart) in Nova Scotia, Canada. We tested the effects of trap type, trap colour, trap height, and lure on the numbers of O. fagi captured per trap with the objective of developing a survey tool to monitor the weevil’s spread. We captured O. fagi in significantly greater numbers on yellow, green, or white traps than on light blue, dark blue, or red traps. There were no significant interactions between trap colour and trap design. Sticky triangular prism traps caught significantly more O. fagi than did nonsticky intercept traps regardless of colour. No effect of trap height was observed. Mean catch of O. fagi was significantly greater on yellow sticky triangular prism traps than on commercially sourced yellow sticky cards. Baiting yellow, green, or white sticky prism traps with the host volatile 9-geranyl-p-cymene did not increase catch of O. fagi. Our results suggest that yellow, green, or white sticky prism traps are a useful tool for detecting O. fagi adults and monitoring the spread of this species in Canada.