Comparative Pathogenesis of Generalist AcMNPV and Specific RanuNPV in Larvae of Rachiplusia nu (Lepidoptera: Noctuidae) Following Single and Mixed Inoculations

The South American soybean pest, Rachiplusia nu (Guenée), is naturally infected by Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Rachiplusia nu nucleopolyhedrovirus (RanuNPV). We compared their pathogenicity to fourth-instar R. nu larvae, by evaluating time to death and virus spread throughout the tissues in single and mixed infections. Bioassays showed that generalist AcMNPV had a faster speed of kill than specific RanuNPV, while the mixed-virus treatment did not statistically differ from AcMNPV alone. Histopathology evidenced similar tissue tropism for both viruses, but co-inoculation resulted in mostly AcMNPV-infected cells. In sequential inoculations, however, the first virus administered predominated over the second one. Implications on baculovirus interactions and biocontrol potential are discussed.

Effect of several types of insecticide on predator population and damage intensity due to soybean pest attack in South Sulawesi, Indonesia

Spodoptera litura was one of the pests that caused soybean seed yield decrease in South Sulawesi. In order to challenge the pests, farmers still largely choose chemical insecticides. This research aimed to establish effectiveness level of several insecticide types that were frequently used by farmers. The design used was Randomized Block Design with 7 treatments (6 insecticide types and 1 control) with 3 replications. The insecticide types examined were: 1) acephate 75%, 2) thiamethoxam 200 g/L + chlorantraniliprole 100 g/L, 3) permethrin 200 g/L, 4) chlorpyrifos 550 g/L + cypermethrin 60 g/L, 5) deltamethrin 50 g/L, 6) profenofos 500 g/L, and 7) polyculture, soybean + corn (control). The result showed that insecticide type of thiamethoxam 200 g/L + chlorantraniliprole 100 g/L was the most effective insecticide to control S. litura with soybean leaves damage intensity (15.19%) and population of Bemisia tabaci whitefly (5.07 tails plant-1). However, thiamethoxam 200 g/L + chlorantraniliprole 100 g/L mostly killed Lycosa sp. predator (0.63 tails plant-1) and Crocothemis servillia (3.26 tails plant-1). The highest predator population was found in multiple cropping of soybean and corn, C. servillia (3.94 tails plant-1), and Lycosa sp. (3.26 tails plant-1). The insecticide of chlorpyrifos 550 g/L + cypermethrin 60 g/L were effective to control soybean pod borer pest Etiella zinckenella (2.40%). Furthermore, insecticide of deltamethrin 50 g/L was effective to control Aphis glycines pest (2.05 tails plant-1). Several types of insecticides are effective in controlling S. litura, N. viridula, and B. tabasi pests, but these insecticides are also effective in killing predators. The highest predator population is soybean-corn intercropping. Keywords: Soybean, insecticides, pests, intensity of damage, predators, seed yields.

REVIEW : PENGARUH PEMANASAN GLOBAL TERHADAP INTENSITAS SERANGAN KUTU KEBUL (Bemisia tabbaci Genn ) DAN CARA PENGENDALIANNYA PADA TANAMAN KEDELAI

Global warming has changed global, regional and local climate conditions. Global climate change is caused, among others, by the increase in greenhouse gas emissions (GHG) due to various activities that drive the increase in the earth's temperature. Given that climate is a key element in the metabolic system, plant physiology and crop ecosystems, global climate change will adversely affect the sustainability of agricultural development. The impact of global climate change is the increasing population of pests on agricultural crops. One of the soybean pests whose population is increasing due to the increase in air temperature is the Bemisia tabbaci infestation. Increased pest populations of Bemesia tabbaci infestation in soybean crops cause dwarf leaves of dwarf plants and threatens to increase soybean production. Efforts to overcome the impact of global warming is mainly due to increased pest populations, it is necessary to think and seek breakthroughs to anticipate the explosion of pest populations in soybean crops, among others by: the optimization of natural control, physical and mechanical control and cultivation techniques. The combination of techniques or tactics of the optimal component of soybean pest control technology is established on the basis of appropriate information knowledge about soybean pest, ecosystem and socio-economic based on IPM approach.

Arthropod Invasions Versus Soybean Production in Brazil: A Review

Soybean production in Brazil has been markedly affected by invasions of non-native arthropod species that feed on the crop, severely impacting biodiversity, food security, health, and economic development. Data on soybean production losses and increase in insecticide usage over the last two decades have not been explored in association with past invasion events, and the dynamics underlying the recent blitz of invasive species into Brazil remain largely unclear. We provide a review of arthropod invasions in the Brazilian soybean agroecosystem since 1990, indicating that the introductions of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae), Tetranychus urticae (Koch) (Acari: Tetranychidae), and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) are likely correlated with periods of increase in insecticide usage for soybean production. Using these three cases as examples, we review factors that could lead to increased likelihood of future invasions by particular pests, outlining four possible criteria to evaluate potential invasiveness of non-native arthropods: likelihood of entry, likelihood of establishment, biological features of the species, and availability of control measures. Spodoptera litura (F.) (Lepidoptera: Noctuidae) and Aphis glycines (Matsumura) (Hemiptera: Sternorrhynca) are examples of highly damaging soybean pests, related to one or more of these factors, that could be introduced into Brazil over the next years and which could lead to problematic scenarios. Melanagromyza sojae (Zehnter) (Diptera: Agromyzidae) also meets these criteria and has successfully invaded and colonized Brazilian soybean fields in recent years. Our review identifies current issues within soybean pest management in Brazil and highlights the need to adopt management measures to offset future costs and minimize lost revenue.

Water Loss and Desiccation Tolerance of the Two Yearly Generations of Adult and Nymphal Kudzu Bugs, Megacopta cribraria (Hemiptera: Plataspidae)

Water loss rate, percentage total body water content (%TBW), cuticular permeability (CP), and desiccation tolerance were investigated in adult and immature stages of the invasive kudzu bug, Megacopta cribraria (Fab.) (Hemiptera: Plataspidae), a serious soybean pest and an urban nuisance. Adults and all five nymphal instars were weighed prior to and 2, 4, 6, 8, 10, and 24 h after desiccated at 30 ± 1°C and 0–2% RH. Both % initial mass and %TBW loss increased linearly with time of desiccation. Rates of loss ranged from approximately 1–7%/h. Mortality occurred at 10 h after desiccation. Desiccation tolerance (%TBW lost at death) ranged between 25.6% for first-generation adult females and 75% for first-generation fifth-instar nymphs. First-generation first-instar nymphs had significantly greater %TBW (88.9%) than the other generations and instars, whereas second-generation fifth instars had the lowest %TBW (62.4%). The CP value of first-generation adult females (12.3 ± 1.6 µg cm−1 h−1 mmHg−1) was the greatest across generations. First-generation first instars had the greatest mass loss (111.11 mg/g) among all instars and generations, whereas overwintered second-generation adult females had the lowest mass loss (18.39) across generations. This study demonstrated that desiccation stress differentially affected the survival of adult and nymphal kudzu bugs and may imply that environmental stress can affect the relative abundance of this species in the fields and around homes.