Life history parameters and predation capacities of Nesidiocoris volucer: a new biological control agent for tomato crop

Whiteflies are one of the major pests of tomato under greenhouses, and their control partly relies on biocontrol strategies. Among those biocontrol agents, parasitoids or predators are widely used. However, the introduction of a biocontrol agent in a new area is not trivial. For that reason, we investigated the use of a tropical native mirid, Nesidiocoris volucer (Hemiptera: Miridae), for the biological control of whiteflies among other insect pests on tomato crops under greenhouses in the subtropical island of La Réunion, France. Nesidiocoris volucer life history traits and plant injury were examined. Nymphs developed and survived between 15 and 30°C and required on average 49.41 days at 15°C and on average 10.50 days at 30°C to develop (nymph survival >94%). At 25°C, each female produced on average 65 eggs. Nesidiocoris volucer was able to feed on several prey species, but performed better on whiteflies than on spider mites or thrips. No N. volucer feeding injury was observed on tomato. Nesidiocoris volucer has also been found in tropical countries of Africa, and we believe that the data presented on this natural enemy could be of great importance for the biocontrol of whiteflies in tropical areas.

Florpyrauxifen-Benzyl Selectivity to Rice in Brazilian Conditions

Florpyrauxifen-benzyl (FPB) is a new class of auxinic herbicide developed for selective weed control in rice. This study aimed to evaluate the effect of environmental conditions, P450 inhibitors, rice cultivar response, and gene expression on FPB selectivity in rice. Field experiments established in a randomized block design showed that rice plant injury due to two FPB rates (30 and 60 g ai ha−1) was affected by planting time and rice stage at herbicide application. The injury was higher at the earliest planting season and more in younger plants (V2) than larger (V6 and R0). However, no yield reduction was detected. Under greenhouse conditions, two dose-response experiments in a randomized block design showed that spraying malathion (1 kg ha−1) before FPB application did not reduce herbicide selectivity. The addition of two P450 inhibitors (dietholate and piperonyl butoxide, 10 g a.i. seed-kg−1 and 4.2 kg ai ha−1, respectively) decreased the doses to cause 50% of plant injury (ED50) and growth reduction (GR50). However, it seems not to compromise crop selectivity. Pampeira cultivar showed lower ED50 and GR50 than IRGA 424 RI. A growth chamber experiment was conducted in a completely randomized design to evaluate the gene expression of rice plants sprayed with FPB (30 and 60 g ai ha−1). Results showed downregulation of OsWAKL21.2, an esterase probably related to bio-activation of FPB-ester. However, no effect was detected on CYP71A21 monooxygenase and OsGSTL transferase, enzymes probably related to FPB degradation. Further research should focus on understanding FBP bio-activation as the selective mechanism.

Evaluation of Chemical Seed Treatment to Reduce Injury Caused by Preemergent Herbicides on Direct-seeded Turnips and Collard Greens

Poor competitive ability and limited herbicide options make weed management of Brassica crops difficult. Growers often adopt the use of transplants, which is less efficient in terms of time, material, and labor when compared with direct seeding, resulting in higher prices per unit. Seed treatment with protective compounds could decrease crop injury from preemergent (PRE) herbicides making it profitable to direct-seed Brassica plants for production. Research was conducted to evaluate the ability of three candidate safeners [24-epibrassinolide, melatonin, and ascorbic acid (AsA)] to reduce injury caused by four herbicides (S-metolachlor, pyroxasulfone, halosulfuron, and mesotrione) applied PRE on the collard green cultivar Top Bunch and turnip cultivar Purple Top White Globe. Two independent greenhouse trials were conducted at the Clemson University Coastal Research and Education Center in Charleston, SC. Visual injury of the treated plants was evaluated weekly and dry mass was collected 21 days after treatment. Seed treatment did not reduce injury efficiently caused by pyroxasulfone, halosulfuron, and mesotrione; all doses were lethal for both crops. However, collard seeds treated using melatonin and AsA had 66% and 54% less injury caused by S-metolachlor at 514 g⋅ha–1 a.i., respectively. On turnips, melatonin was the only treatment that reduced the S-metolachlor damage on seedlings, with 43% less injury than untreated seedlings. Plant injury and plant weight correlated significantly for both Brassica crops. The reduction in injury caused by S-metolachlor when seeds were treated with melatonin and AsA validated those compounds’ protective ability. Seed treatment with melatonin could be combined with PRE applications of S-metolachlor to overcome the low weed competitive ability of these species early in the season.

‘Atlantic’ and ‘Dakota Pearl’ Chipping Potato Responses to Glyphosate and Dicamba Simulated Drift

Field trials were conducted to determine the effects of glyphosate and/or dicamba simulated drift rates on chipping potatoes ‘Atlantic’ and ‘Dakota Pearl’. Sublethal herbicide rates were applied at the tuber initiation stage and consisted of dicamba at 99 g ae ha−1 or glyphosate at 197 g ae ha−1 applied alone or the combinations of dicamba at 20 or 99 g ae ha−1 and glyphosate at 40 or 197 g ae ha−1, respectively. At 7 days after treatment (DAT), the high spray combination of glyphosate plus dicamba resulted in the greatest plant damage (28%). Plant injury from plants treated with the low combination of glyphosate plus dicamba did not differ from the nontreated control. At 21 DAT, visible injury increased to 40% for plants treated with the high combination of glyphosate plus dicamba treatment. Total yield suggested that dicamba and glyphosate caused similar yield reductions as plants that received glyphosate at 197 g ha−1 or dicamba at 99 g ha−1 had lower total yields compared to the nontreated and plants that received the combination of glyphosate (197 g ha−1) and dicamba (99 g ha−1) had lower total yields compared to plants that received either herbicide alone. However, ‘Dakota Pearl’ plants were more sensitive to glyphosate at 197 g ha−1 than ‘Atlantic’ causing the interaction for most tuber grades. Tuber specific gravity was lower for plants that received glyphosate at 197 g ha−1, dicamba at 99 g ha−1, or this combination, but this reduction would not prevent chip processing. Results reinforce the need for diligence when applying these herbicides in proximity to a susceptible crop such as chipping potatoes and the need to thoroughly clean sprayers before applications to a sensitive crop.

Sweetpotato Response to Reduced Rates of Dicamba

A field study was conducted in Mississippi to determine the effect of reduced dicamba rates on sweetpotato crop tolerance and storage root yield, simulating off-target movement or sprayer tank contamination. Treatments were a non-treated control and four rates of dicamba [70 g ae ha−1 (1/8X), 35 g ae ha−1 (1/16X), 8.65 g ae ha−1 (1/64X) and 1.09 g ae ha−1 (1/512X)] applied either 3 days before transplanting (DBP) or 1, 3, 5, or 7 weeks after transplanting (WAP). An additional treatment consisted of 560 g ae ha−1 (1X) dicamba applied 3 DBP. Crop injury ratings were taken 1, 2, 3, and 4 weeks after treatment (WAT). Across application timings, predicted sweetpotato plant injury 1, 2, 3, and 4 WAT increased from 3 to 22%, 3 to 32%, 2 to 58%, and 1 to 64% as dicamba rate increased from 0 to 70 g ha−1 (1/8X), respectively. As dicamba rate increased from 1/512X to 1/8X, predicted No. 1 yield decreased from 127 to 55%, 103 to 69%, 124 to 31%, and 124 to 41% of the non-treated control for applications made 1, 3, 5, and 7 WAP, respectively. Similarly, as dicamba rate increased from 1/512X to 1/8X, predicted marketable yield decreased from 123 to 57%, 107 to 77%, 121 to 44%, and 110 to 53% of the non-treated control for applications made 1, 3, 5, and 7 WAP, respectively. Dicamba residue (5.3 to 14.3 parts per billion) was detected in roots treated with 1/16X or 1/8X dicamba applied 5 or 7 WAP and 1/64X dicamba applied 7 WAP with the highest residue detected in roots harvested from sweetpotato plants treated at 7 WAP. Collectively, care should be taken to avoid sweetpotato exposure to dicamba especially at 1/8X and 1/16X rates during the growing season.

Halyomorpha halys (Hemiptera: Pentatomidae) as a Potential Risk for Early Vegetative-Stage Sweet Corn

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive species in the United States representing a great threat to crops of economic importance, such as soybean and corn. Due to the lack of information about its damage to early vegetative-stage corn, this study was conducted to provide information about H. halys damage to sweet corn seedlings. In the field experiment, caged sweet corn seedlings were exposed to sexed H. halys adults of densities of 0, 1, or 2 insects per plant for 7 d. In a complementary greenhouse experiment, caged sweet corn seedlings were exposed to 0 or 2 nonsexed H. halys at different stages (second to fifth instars and adult) per plant for 14 d. In both experiments, we evaluated plant fresh and dry weights, plant height, stalk diameter and plant injury (using a rating scale, 0 to 5). In the field experiment, plant injury based on the rating scale was greater in plants exposed to insects compared with the control. In the greenhouse experiment, fresh and dry weights, height and diameter of seedlings were lower for those exposed to fourth instars. This stage also caused greater injury based on the rating scale. In general, our results indicate that H. halys can feed on sweet corn seedlings, and that fourth instars cause more injury. The rating scale adapted here can be used for early identification of H. halys occurrence and to assess its injury in the field.

Wound infection by Pantoea agglomerans after penetrating plant injury

Pantoea agglomerans is a ubiquitous gram-negative bacterium that has been linked to skin and joint infections secondary to plant injuries. Herein we report a 58-year-old woman who presented with 2 erythematous nodules with purulent discharge on the anterior aspect of the right leg that developed after a penetrating plant injury. The patient was initially treated with amoxicillin-clavulanic acid, cloxacillin and clindamycin without improvement. P. agglomerans was isolated from both exudate and skin biopsy cultures. Healing of the lesions was achieved after the spontaneous release of a retained plant fragment and treatment with cotrimoxazole. Identification of P. agglomerans in persistent exudative lesions should alert the clinician regarding a possible previous plant injury and retained vegetal fragments. Conventional antibiotic treatment and the extraction of retained foreign bodies usually lead to complete resolution.

Evaluating Sugarcane Aphid, Melanaphis sacchari (Hemiptera: Aphididae), Population Dynamics, Feeding Injury, and Grain Yield Among Commercial Sorghum Varieties in Alabama

The sugarcane aphid, Melanaphis sacchari (Zehntner), emerged as a severe pest of sorghum, Sorghum bicolor (L.), in Texas and Louisiana in 2013 and currently threatens nearly all sorghum production in the United States. Proper management of populations is critical as sugarcane aphid has a high reproductive potential and can rapidly damage plants, resulting in extensive yield losses. The overall objective of this work was to investigate sugarcane aphid population dynamics, and subsequent sorghum injury and grain yield on commercially available grain sorghum varieties in Alabama. This research includes three-site years of data that show variation in plant injury, physiological maturity, and yields among varieties tested. Although performance of each variety was variable among locations, potentially due to abiotic factors, four varieties including DKS 37-07, 1G588, 1G855, and 83P17 exhibited characteristics consistent with resistance and corroborates reports of resistance from other states.

Mustard Aphid and Crop Production

Mustard aphid, Lipaphis erysimi (L.) Kaltenbach (Homoptera: Aphididae) is the most notorious, cosmopolitan louse-like and obligate ectoparasite, which causes a bulk of the qualitative and quantitative loss of rapeseed-mustard crops. This article reviews the general overview of biology, damages, and the management of mustard aphids. Biologically, L. erysimi adults are soft bodies, varying in color mostly yellowish-greenish, small to medium-sized, globular, pear-shaped, manifesting wing dimorphism based on the resource availability. Plasticity in reproductive mode either sexually or asexually stimulated as an adaptive response to cope with seasonal fluctuations, maximizes the chance of survival from predators being outnumbering. Mustard aphid infested host plant in three major ways, firstly by sucking the plant phloem through stylets, the needle-like piercing-sucking mouthparts which manifest injury like curling and yellowing of the leaf, stunting and drying up of the plants. Secondly, by excreting a sticky substance (honeydew) on which 'sooty mold' growth, which blocks the process of photosynthesis. Thirdly, it causes secondary plant injury by transmission and dissemination of viruses including turnip mosaic viruses. The appearance, multiplication, and disappearance of mustard aphid are largely regulated by weather variations. Its prolific multiplication greatly thrives by cool, wet, and cloudy weather. The mustard aphid can be eschewed more so if the crop is sown before 20th October. Applications of the recommended dose of fertilizers, irrigation, resistant varieties are some cultural practices to cope with the aphid population. Natural enemies are effective and impressive nowadays for crop protection. Ladybird beetles viz., Cocciniella septempunctata, Hippodamia variegata, and Cheilomones vicina are active predators of this pest. Chemical control includes the application of systemic insecticides below the ETL (Economic Threshold Level). Some major insecticide includes are Imidacloprid 17.8% @ 0.25 ml/l, Thiamethoxam 25 WG @ 0.2g/l and Dimethoate 30EC @ 1 ml/l of water. Int. J. Appl. Sci. Biotechnol. Vol 8(3): 310-317