Plant Protection News

Influence of adult density and plant type on the fertility of females of the predatory bug Macrolophus pygmaeus (Heteroptera, Miridae) during mass culture

2024-08-20T09:47:44+00:00

Macrolophus pygmaeus (Heteroptera: Miridae) is a predatory bug widely used in plant protection for pest control. During mass breeding, an important role in obtaining entomophagous products at the lowest cost is played by the selection of the optimal density of oviparous adults on the plant for oviposition and the type of host plant. In this study, we assessed the influence of the density of adult bugs and two species of tobacco, the ornamental tobacco Nicotiana alata and the cultivated tobacco N. tabacum, on female fertility. It has been established that the fertility of females is influenced by both the total leaf surface area and the size of optimal sites (main vein length) for oviposition. The volume of production is determined both by the fertility of females at different densities of their content on the plant, and by the number of females per unit area of leaf surface. The results of assessment of productivity of two tobacco species demonstrate that the higher productivity in the cultivated tobacco is achieved at the density of 20 to 30 pairs per plant, while in the ornamental tobacco – 35 to 60. To obtain the maximal productivity, the more suitable plant was the ornamental tobacco N. alata with the adult density of 40 pairs per plant.

Assessing the phytosociological characteristics of weed complex in okra field under different control strategies

2024-08-20T09:47:44+00:00

Weed diversity is crucial for supporting ecological services, but weed control methods significantly influence weed species dominance and diversity. The present study was conducted in southwestern Nigeria’s rainforest-savanna transitional agroecological zone during the 2017 and 2018 rainy seasons. Different weed management techniques were assessed, including applying cyanide-сontaining cassava effluent (CE@3WAS), pendimethalin (P), and hoe weeding (HW@3WAS), as well as repeated applications of HW and CE (HW@3&5WAS, CE@3&5WAS), and integrated approaches (P + CE@5WAS, P + HW@5WAS, CE@3WAS + HW@5WAS). A control treatment, where the weeds were left unmanaged, was also included. The experiment followed a randomized complete block design with three replications. Weed samples were collected using 25 cm x 25 cm quadrats placed randomly along the plot diagonals. Weed diversity was assessed using the ShannonWiener index and descriptive statistics. Results indicated that the control methods influenced weed species composition. Specifically, the presence of broad-leaf weeds was prominent in the P + HW@5WAS (2017) and P + CE@5WAS (2018) treatments, while grasses dominated in the weedy check (2017) and HW@3WAS (2018), suggesting that these strategies favour specific morphological groups of the weeds. Weed diversity decreased across various management practices, with the rankings in ascending order: CE@3&5WAP, CE@3WAP, P+CE@5WAS, CE@3WAP + HW@5WAP, P + HW@5WAP, Pendimethalin, HW@3WAP, and HW@3&5WAP. These findings underscore the importance of selecting weed management strategies based on weed ecological significance. Integrated weed management emerged as a more ecologically sustainable approach for okra fields compared to sole herbicide application or manual weeding.

Identification of the lupine aphid Macrosiphum albifrons (Hemiptera, Aphididae) using molecular markers

2024-08-20T09:47:45+00:00

Narrow-leaved lupine is a valuable high-protein fodder crop, also promising for food use. The species composition of harmful organisms feeding on lupine has not been sufficiently studied. In 2019–2021 in the north-west of the Russian Federation (St. Petersburg, Pushkin), the species composition of insects inhabiting accessions of lupine of various origins was studied. The lupine aphid Macrosiphum albifrons, an invasive phytophagous pest of North American origin, was discovered for the first time in Russia. Using sequencing of a fragment of the mitochondrial gene for cytochrome c-oxidase subunit 1 (CO1), traditionally used for diagnosing Aphididae, the correctness of determining the species identity of the insect was verified. Specific primers have been proposed that allow amplification of a 408 bp portion of the barcode DNA to identify the pest.