Journal of Applied Entomologist

Effective control of invasive grape mealybugs (Maconellicoccus hirsutus) involves cautious release of ladybird beetles in variable temperature parameters

Mr. Janak Pant, Mrs. Prava Dawadi — Fri, 03 Jan 2025 00:00:00 +0000

Objective: The investigation on mealybug Maconellicoccus hirsutus control in grape (Vitis vinifera) has not been carried out in Jumla, Nepal. So, a study was carried out in Chandannath, Jumla in selected grape vineyards (Vitis vinifera) to understand the effectiveness of various treatments in the mealybug M. hirsutus population.

Methods: The vineyard was screened with net that were deployed to find out the efficacy of 3 treatments namely seven spotted ladybird beetles Coccinella septempunctata (10 ladybird beetles released just before the monitoring and prior surveillance of beetles carried in the field), Imidacloprid 200 SL @1.5 ml/l of water/plant), and untreated control in controlling mealybugs Maconellicoccus hirsutus. In addition, laboratory study was conducted to understand the effect of fluctuating temperature and mealybug population in presence of ladybird beetles.

Results: At 10⁰c the numbers of mealybugs were 500, and they decreased to 450 and 395 at 12 and 14⁰c respectively. At 28 and 30⁰c they became 9 and 2 in numbers. The temperature was found significant to the population of mealybugs M. hirsutus, however the growth and development of ladybird beetles C. septempunctata were severely affected, while their feeding habit was directly correlated with increased temperature. The effect of ladybird beetles was highly effective in controlling the population of mealybugs in grape vineyards followed by the effect of imidacloprid and untreated control. The average yield (kg/plant) were 6, 8 and 4 in imidacloprid sprayed, ladybird beetle released and untreated control sprayed vineyard respectively. Grape cluster and yield were highest in ladybird beetle released vineyards followed by imidacloprid and untreated control.

Conclusion: Therefore, the ladybird beetle C. septempunctata could be the effective strategy in controlling invasive mealybug Maconellicoccus hirsutus in grape (Vitis vinifera) vineyards at changing temperature.

Development of Hexamermis vishwakarma Dhiman (Nematoda: Mermithidae), a parasitoid of Leptocoris augur (Fabr.)

Kumkum — Tue, 07 Jan 2025 00:00:00 +0000

Leptocoris augur, a well-known pest of the "Kusum" plant Schleichera oleosa Lour, is endoparasited by Hexamermis vishwakarma Dhiman. Using a two-tray technique, this worm has been successfully raised in a lab to learn about its biology. The five stages of this parasitoid's life cycle are eggs, pre-parasitic juvenile, parasitic juvenile, post-parasitic juvenile, and adult. Within 20 to 72 hours of the male and female post-parasitic nematodes mounting into adults, copulation takes place, lasting approximately 30 minutes, according to the biology of H. vishwakarma. After 10 to 25 days, ovipositions start on average 14 days after copulation. They produce 40 to 60 eggs per day for approximately a week, following which a few days must pass. Approximately 1200 to 1600 (on average, 1400) eggs are deposited during the course of 40 to 50 days. Internal fertilization occurs in the oviduct, which is the upper portion of the uterus. The incubation period, which lasts from July to September during the wet season, averages 16.5 days but can range from 14 to 20 days. The process of "spontaneous" egg hatching takes roughly 13 minutes on average, with an average of 1.5 minutes. The pre-parasitic juvenile enters the surrounding water after hatching. Its length ranges from 0.25 to 0.80 mm (average of 0.70 mm); they can live for three to five days without the host or culture media. Within 15 to 4 hours, the pre-parasitic juvenile enters the host bug and begins consuming nutrients from the adipose tissue, muscles, and haemo-coelomic fluid. As it grows in size, it is referred to as a "parasitic juvenile."

The size of parasitic- Juvenile juvenile parasites range in length from 12.0 to 194.0 mm and breadth from 1.25 to 2.25 mm. With an average of 20.5 days, the duration from penetration to emergency is estimated to be between 18 and 22 days. Parasitic juveniles are now known as "post-parasitic juveniles" once they emerge. While female nematodes are 52.0 to 194.0 mm in length and 2.00 to 2.25 mm in width, males are smaller, measuring 12.0 to 49.0 mm in length and 1.25 to 1.40 mm in width. Finally, within 17 to 30 days (on average, 24 days), post-parasitic juveniles moult in two adults. Adults resemble post-parasitic nematodes, with the exception that their vulva, spicules, and other features are completely formed. Furthermore, depending on changes in temperature and relative humidity as well as the condition of post-parasitic nematodes, the lifespan of male adults of Hexamermis vishwakarma ranges from 30 to 40 days, while that of female adults varies from 40 to 50 days.

Spinning secrets of Dineutus sp (Macleay, 1825) in Kangsabati River, West Bengal, India

Joydeep Das, Joydev Maity — Fri, 10 Jan 2025 00:00:00 +0000

A study was carried out on aquatic insect, Dineutus sp, of Kangsabati River at two sites, Kangsabati Rail bridge region (site-A), Dherua Bridge Region (site-B) of district Paschim Medinipur, West Bengal. The sampling was done monthly from January,2024 to January 2025. Due to its inclination to gyrate or skate in schools supported by surface tension, the Gyrinidae family is known as the "Whirligig Beetles." Their antennae are small and stout, and their middle and hind legs have been reshaped to seem more like paddles than legs. Their eyes are split into two sections, the lowest of which is below the water's surface and the top of which is above it. The female copulates on the water's surface and lays her eggs on emergent vegetation stems a few centimetres below the water's surface. They are one of the most well-known water beetle groups, and when handled, they emit a pleasant odour. When we were studied in river Kangsabati, we were found this species. The aim of this paper is to give interesting fact of this insect species.

Response of maize hybrids to Spodoptera frugiperda (J. E. Smith) infestation and the impact of insecticides under field conditions

Thu, 16 Jan 2025 00:00:00 +0000

This study was carried out to evaluate the relative susceptibility of eight maize hybrids to Spodoptera frugiperda (J. E. Smith) infestation under field conditions during 2023 and 2024 seasons at Nubaria district, Beheira Governorate, Egypt. The results revealed that none of the hybrids exhibited high resistantance to the pest, but SC128 and SC130 hybrids showed moderate resistance. In the first season, TW352 and TW360 hybrids received the highest number of egg masses, while SC130 and SC128 were the least attractive for oviposition. A similar trend was observed in 2024, with TW352 and TW360 being the most preferred for oviposition. The abundance of larvae was measured during both seasons, showing that TW352 hosted the highest number of larvae, while SC130 had the lowest. These findings were consistent across the two years. Additionally, the infestation percentages were highest in TW352 and lowest in SC130. In both years, infestation percentages significantly differed among the hybrids, indicating into variations in susceptibility. Insecticidal treatments revealed that Pleo and Lannate were the highest efficient, with Pleo exhibiting the best residual effect. Coragen, though effective, induced the lowest larval mortality rate in both seasons. This research highlights the importance of selecting maize hybrids resistant to S. frugiperda, with the application of effective insecticides to manage S. frugiperda infestations. These results contribute valuable insights for enhancing maize pest management programs and improving crop protection strategies.

The effect of weed species on the survival and reproduction of Green Leafhopper Nephotettix virescens (Distant)

Nurjannah Hasibuan, B. Manurung — Mon, 03 Feb 2025 00:00:00 +0000

This study aimed to assess the effect of different weed species on the survival and reproductive success of the green leafhopper Nephotettix virescens and to determine which weed species that can to supports leafhopper survival. The study was carried out in randomized complete block design with three replications across three weed types (Leersia hexandra, Cyperus rotundus, Echinochloa crusgalli) and rice (Oryza sativa) as a control. Research results showed that N. virescens has the longest survival on rice, followed by the weeds of Leersia hexandra, Cyperus rotundus, and Echinochloa crusgalli (Fc = 23.79; P= 0.01). The highest of offspring number was observed on rice, be followed on Cyperus rotundus, Leersia hexandra, and Echinochloa crus-galli (Fc = 8.45; P = 0.01). Cyperus rotundus and Leersia hexandra could supported the survival and reproduction of N. virescens.