Evaluation of Silica-Coated Insect Proof Nets for the Control of Aphis fabae, Sitophilus oryzae, and Tribolium confusum

Abstract

Insect proof nets are widely used in agriculture as mechanical and physical barriers to regulate pest populations in a greenhouse. However, their integration in the greenhouse ventilation openings is highly associated with the decrease of air flow and the adequate ventilation. Thus, there is need for alternative pest management tools that do not impair adequate ventilation. In the present study, we tested four net formulations of relatively large mesh size coated with SiO2 nanoparticles, namely, ED3, ED3-P, ED5, and ED5-P to evaluate their insecticidal properties against adults of Aphis fabae and Sitophilus oryzae and larvae of Tribolium confusum. ED3 and ED5 nets were coated with SiO2 nanoparticles of different diameter, while in the case of ED3-P and ED5-P, paraffin was added to increase the mass of the deposited particles on the net’s surface. In the first series of bioassays, the knockdown and mortality rates of these species were evaluated after exposure to the aforementioned net formulations for 5, 10, 15, 20, 25, 30, 60, 90, and 180 min. In the second series of bioassays, knockdown and mortality of these species were recorded after 1, 7, and 10 days of post-exposure to the nets for different time intervals (15, 30, and 60 min). Based on our results, all nets significantly affected A. fabae, since all insects were dead at the 1-day post-exposure period to the silica-treated nets. Conversely, at the same interval, no effect on either S. oryzae adults or T. confusum larvae was observed. However, in the case of S. oryzae, the efficacy of all nets reached 100% 7 days after the exposure, even for adults that had been initially exposed for 15 min to the treated nets. Among the species tested, T. confusum larvae exhibited the lowest mortality rate, which did not exceed 34% at the 10 days of post-exposure interval. Our work underlines the efficacy of treated nets in pest management programs, under different application scenarios, at the pre- and post-harvest stages of agricultural commodities.

Synthetic and Natural Insecticides: Gas, Liquid, Gel and Solid Formulations for Stored-Product and Food-Industry Pest Control

“…Recently, mesh insecticidal products have been produced to protect expensive food products against storage pests ( Figure 5 Q). Specifically, Agrafioti et al [ 589 ] tested the efficacy of nets coated with SiO 2 dust nanoparticles under different pre- and post-harvest application scenarios. Polyester insecticide-impregnated net technologies, such as alpha-cypermethrin-coated polyester nets (Carifend ® ), were suggested to protect tobacco products from the cigarette beetle Lasioderma serricorne (F.) (Ptinidae) and the tobacco moth E. elutella .…”

SiO2 Applications as an Alternative to Insect Control in Greenhouses

“…Unlike S. oryzae, T. confusum, larvae were more tolerant to such formulations, requiring at least 8.5 h of continuous exposure to achieve KD t99 . Moreover, in the same study, long term exposure bioassays were assessed, suggesting that the delayed mortality of the insects was increased to 100% after 7 days post-exposure for only 15 min to the SiO 2 nanoparticles [9]. However, desiccation is more likely to occur for soft-bodied insects such as aphids, whilst in the case of stored-product insects, water loss becomes more difficult due to their hard exoskeleton.…”

“…Our results are in agreement with those of the aforementioned study, as paraffin did not play a decisive role in insect mortality. The delayed mortality recorded for both of the tested stored-product insects can also be associated with the slow-acting mode of inert dusts, as the mortality is possible to occur over a period of weeks after continuous exposure to the screens [9]. There are also cases where some species such as T. confusum larvae, although soft-bodied, are extremely tolerant to water loss.…”

“…In a recent study, it was demonstrated that a significant mortality of S. oryzae and T. confusum is likely to occur at a slower rate when exposed to siliceous nanoparticles, as they are considerably hard-bodied and tolerant insects [8]. Following the previous study, the insecticidal efficacy of a 50-mesh size screen coated with SiO 2 nanoparticles was evaluated under laboratory conditions against S. oryzae and T. confusum [9]. The results indicated the efficiency of SiO 2 nanoparticles as an alternative insect control agent, as delayed mortality was promoted after 7 days of post-exposure to the treated screens.…”

Green Synthesis of Nanomaterials and Their Biological Applications

“…(i) Green-based processes improving the stability of nanomaterials [2]; (ii) The development of green synthesis protocols for the preparation of nanomaterials with antibacterial and anticancer activity, as well as acting as catalytic reductors of nitrophenols [3]; (iii) The development of novel insecticides against key insect pests, including highly stable insecticidal nanoemulsions toxic to moth larvae [4], as well as silica-nanoparticlecoated insecticidal nets effective against aphids and stored-product beetles [5]; (iv) The development of new terahertz metamaterials for biosensing applications [6,7].…”