Susceptibility of corn to stink bug (Dichelops melacanthus) and its management through seed treatment

Abstract

We determined the susceptibility of vegetative corn stages to Dichelops melacanthus damage, and how seed treatment can reduce damage and yield loss. Two field trials were carried out. In the first, corn plants were artificially infested with D. melacanthus male/female pairs at rate of 0.5 pair per plant at different vegetative stages and infestation periods lasting 7-28 days (V1-V3, V1-V5, V1-V7, V1-V9, V3-V5, V3-V7, V3-V9, V5-V7, V5-V9, and V7-V9), plus a control without infestation. In the second, corn plants were artificially infested at a rate of one male/female pair per plant at different vegetative stages and infestation periods (V1-V3, V1-V5, V1-V7, V3-V5, V3-V7 and V5-V7) and treated with two pesticide seed coatings: (i) fungicide [carbendazim + thiram (150 g i.a. per L and 350 g i.a. per L)] + insecticide [clothianidin (600 g i.a. per L)] or (ii) only fungicide (carbendazim + thiram), plus three controls without infestation and with only fungicide-treatment (V1-V7, V3-V7 and V5-V7). In both trials, plants were caged during the entire period in order to hold stink bugs in contact with plants and to avoid injury from other arthropods. The most stink bug susceptible corn growth periods were from V1-V5 and from V1-V7. Seed treatment with clothianidin at the rate of 3.5 mL per Kg during the most susceptible infestation periods increased yield gain of 37.8 to 61%. Treatment with clothianidin during V1-V5 and V1-V7 caused 40% to 50% D. melacanthus adult mortality, respectively.

Damage caused by Diceraeus (= Dichelops) melacanthus in maize plants subjected to combinations: bioinoculation and imidacloprid seed treatment

“…The infestation of corn plants occurred at development stage V1 (first expanded leaf) (Magalhães & Durães, 2006), and lasted 15 days (adapted from Bridi et al, 2016). This time interval is when maize is higly susceptive to stink bug damage (Silva et al, 2019). For the plant infestation, two unsexed adult insects were used per sample unit (pot), corresponding to one insect/plant.…”

“…Currently, one of the main maize crop pests in Brazil is the stink bug Diceraeus (= Dichelops) melacanthus (Hemiptera: Pentatomidae), which causes crop losses of 20% (Cruz et al, 2016) to approximately 100% (Silva et al, 2019;2021). The use of insecticides for seed treatment Orcial Ceolin Bortolotto et al…”

“…has been essential to mitigate crop damage. One class of insecticides, neonicotinoids, are effective because of their systemic translocation in plants (Silva et al, 2019), meaning they can protect maize plants shortly after emergence (usually between the first five to 10 days). Common neonicotinoids in Brazil include clothianidin, thiamethoxam, and imidacloprid (Silva et al, 2021).…”