Antonia Lopes de Mendonça Zaidem

A mosca branca Bemisia tabaci é uma das mais importantes pragas do feijoeiro, principalmente devido à transmissão de viroses. O controle dessa praga tem sido realizado com uso intensivo de agrotóxicos, o que além de ser potencialmente nocivo ao ambiente, é oneroso e por vezes, ineficaz. Por essa razão, é necessário desenvolver novas ferramentas de controle da mosca branca que contribuam com o manejo racional de agrotóxicos, como por exemplo, o uso de radiação eletromagnética LASER, que pode ser uma opção mais sustentável por não deixar resíduos no ambiente.

The whitefly Bemisia tabaci is among the most important agricultural pests in the world and one of the world’s top 10 most invasive insect pests. Bemisia tabaci is associated with severe yield and quality losses, mainly due to the transmission of plant viruses, as in the case of common beans (Phaseolus vulgaris L.). Reducing insecticide applications is a research priority, e.g., developing innovative and clean tools such as electromagnetic waves. The present work aims to determine the effective parameters of laser to reduce the Bemisia tabaci population in common beans. Preliminary assays were conducted by manually irradiating continuous-wave laser beams with different wavelengths (444 nm, 527 nm, and 640 nm) and optical intensities directly on the insects. Among these, the most effective wavelength was 444 nm. Later, we repeated the experiments using a homemade automated system to control the exposure time (t₁ = 1 s, t₂ = 2 s, t₃ = 3 s and t₄ = 4 s) of whiteflies to the incident beam at different optical intensities (I₁ ≈ 10 Wcm⁻², I₂ ≈ 4 Wcm⁻², I₃ ≈ 2 Wcm⁻²). We have achieved 100% insect mortality by irradiating 454 nm laser wavelength on the 3rd instar nymphs of Bemisia tabaci, with the following parameters: I₁(t₁), I₂(t₃) and I₃(t₄). Moreover, the laser irradiation test did not affect plant yield and development, revealing that our preliminary results present a photonic technique that could control whiteflies without harming the plants’ development.