Water in maize whorl enhances the control of Spodoptera frugiperda with insecticides

Abstract

<jats:p>ABSTRACT The fall armyworm Spodoptera frugiperda is among the main insect-pests on maize crops, due to its damaging potential and control issues related to the larval habit of concealing itself within the plant whorl. This study aimed to evaluate the effect of water in the maize whorl, combined with insecticides and spray sets, on the damage caused by S. frugiperda and the grain yield. The experiments were carried out under field conditions, at two cropping seasons, both with Bt-maize hybrids, in a 2 × 2 × 5 + 1 factorial scheme, testing the presence or absence of water inside the plant whorl, two insecticides and five spray sets (combinations of spray volumes, nozzle types, pressures and spraying speed), plus a control without water and insecticide. The presence of water inside the whorl reduced the damage caused by S. frugiperda during the early growth stages, especially in the plants sprayed with the insecticide chlorantraniliprole. The spray sets with 200 L ha1/20.3 psi or 250 L ha1/33.4 psi provided the highest reductions in the percentage of damaged plants and damage scores, regardless of the insecticide. Therefore, the spraying of insecticides, when there is water from irrigation, dew or rainfall inside the maize whorl, improves the control of S. frugiperda in maize crops, especially in Bt-maize.</jats:p>

Egg cluster characteristics of fall armyworm, <em>Spodoptera frugiperda</em> (Lepidoptera: Noctuidea) in Sri Lanka under laboratory conditions

“…Such characters are known to have developed insecticide resistance in eggs (Campbell et al, 2016), and resistance to chemicals in S. frugiperda have often resulted in pest resurgence (Assefa and Ayalew, 2019). However, control of S. frugiperda when in the egg stage is more effective as larvae migrate into the plant whorl immediately after its emergence and remain sheltered during the whole larval phase inflicting a serious downside to insecticide spraying (Bialozor et al, 2020). Small-holder farmers of many countries carry out handpicking and crushing of egg masses of S. frugiperda, especially as the method is cheap and it only requires readily available material (Ahissou et al, 2021;Njuguna et al, 2021).…”

Efficacy of Insecticides Applied to Soybean Seeds for Controlling Lepidoptera Caterpillars

“…in Bt soybean crops, since there are precedents regarding the natural tolerance of the species to the Cry1A protein and resistance to insecticides (Murúa et al, 2018). Insecticide resistance is an important factor that has influenced pest control for more than half a century (Sparks, 2015;Bialozor et al, 2020).…”