Abundance of sucking insect pests on some flowering plants in relation to weather parameters

The study was conducted from November 2017 to May 2018 in the experimental field at Gazipur, Bangladesh to investigate the incidence of sucking pests namely gladiolus thrips Teniothrips simplex, tuberose aphid Aphis craccivora, marigold aphid Neotoxoptera oliveri, and dahlia mealybug Plannococcus citri on their cultivated host plants in relation to temperature, relative humidity and rainfall. Results showed that the abundance of gladiolus thrips, tuberose aphid, marigold aphid and dahlia mealy bug reached the peak in the 3rd week of January, 3rd week of February, 1st week of January and 1st week of February, respectively. Among the weather factors, temperature had significant negative impact on the abundance of gladiolus thrips, marigold aphid and tuberose aphid, whereas rainfall showed significant negative influence only on marigold aphid. Multiple linear regression analysis showed that weather variables collectively predicted 55.9%, 75.9%, 44.5%, and 34.6% abundances of gladiolus thrips, marigold aphid, tuberose aphid and dahlia mealybug, respectively. Bangladesh J. Sci. Ind. Res.56(4), 241-248, 2021

Weather based pest forewarning models for mealybug infestation in Robusta coffee (Coffea canephora)

An investigation was carried out to study the effect of weather parameters on mealybug infestation in Robusta coffee and to develop forewarning model using 39 years (1977 to 2015) pest data on mealy bug damage in coffee plantations collected at Regional Coffee Research Station, Chundale, Wayanad district of Kerala were recorded at fortnightly intervals during 1977 to 2015 (39 years). The results revealed that mealybug infestation was found to vary with season and also year to year. Fruit setting and budding stages of coffee were severely damaged by mealy bug. Analysis indicated that annually, average damage due to mealy bug was 6.4 per cent and ranged between 5.4 per cent in 1984 to 9.7 per cent in 2011. The mealybug damage was maximum during summer season and lowest during South-West Monsoon (June-September) season. Season wise regression models were developed using data up to 2013 for forewarning per cent damage of mealy bug and validated for 2014 and 2015. The model for summer season mealybug damage has maximum R2=0.79 which can be used for operational forecasting of mealy bug damage.

Management of the grape mealy bug, Maconellicoccus hirsutus (Green), using entomopathogenic fungi and botanical oils: a laboratory study

Background Laboratory experiments were conducted to evaluate the bio-efficacy and cumulative effect of entomopathogenic fungi (EPF), viz., Lecanicillium lecanii (Zimmermann) Zare and Gams, and Beauveria bassiana (Balsamo) Vuillemin and different botanical oils against grape mealy bug, Maconellicoccus hirsutus (Green). M. hirsutus infestation during berry formation has left no option other than chemical management. However, the pesticide application during this stage leads to residues. Thus, safer and sustainable biological need was tested for their effectiveness against M. hirsutus. Results Dipping bioassay technique was used to determine the cumulative mortality. When L. lecanii was used as sole (at 6 and 4 g/l), significant mortality was observed (51.63 and 50.18%). However, the maximum cumulative nymphal mortality was achieved when the combination of EPF formulations was used, i.e., 57.64% with B. bassiana + L. lecanii (6 g/l + 6 g/l). Their effectiveness was at par with the same combination but with minimal concentration, i.e., 4 g/l + 4 g/l (56.29%). Concerning the botanical oils evaluated, neem oil at 15 ml/l achieved a higher mortality of 81.36%. Consecutive effective treatment was a combination of neem oil and pongamia oil (at 10 + 10 ml/l) with 79.65% mortality. However, the standard dosage of neem oil (at 10 ml/l) and IIHR neem soap (at 10 g/l) also recorded the significant mortality of 78.09 and 77.67%, respectively. When compared, the neem oil was found significantly superior in sole and compatible combination than pongamia oil. Conclusions Lecanicillium lecanii and neem oil (sole and in combination with other compatible bioagents) proved significantly better for the management against M. hirsutus with an efficacy of 90.21 and 96.67 % mortality, respectively against the standard chemical control (more than 97%).

By-product hydrosol of Eucalyptus globulus essential oil distillation as source of botanical insecticides: wealth from waste

Worldwide use of chemical pesticides is on rise which is creating a big problem to environment and human health. Hence great interest has been generated to find out botanical leads having anti-pest properties from medicinal plants. The objective of this work was to evaluate the insecticidal potential of Eucalyptus globulus waste hydrosol obtained after essential oil distillation. Samples of Eucalyptus globulus genus were collected from near-by areas of study, and were hydro-distilled and their by-product ‘hydrosol was analyzed for phenolics and tannin determination. UV-VIS, FT-IR and fluorescent study was also conducted of by-product hydrosol. In addition, insecticidal activity of by-product hydrosol was also monitored against mealy bug. Substantial amount of phenolics and tannins were detected in the by-product hydrosol. UV and fluorescent spectroscopy revealed the presence of secondary metabolites. Significantly higher insecticidal activity was observed of by-product hydrosol against mealy bug. The results suggested that by-product hydrosol from Eucalyptus globulus essential oil distillation can be considered as potential candidates for bio-control of pests.

Testing the Relative Efficacies of Three Different Integrated Pest Management (IPM) Modules for Controlling Mango Mealy Bug (Drosicha mangiferae G.) at Malda, West Bengal

Background: Mango mealy bug (Drosicha mangiferae G.) is a notorious pest of mango and when infestation reaches severity quantum fruit loss takes place. Control of this pest had been found to be impossible with conventional chemical pesticide spray. So, the urgent need is to find some non conventional management practices. Therefore, the current study was undertaken to test three different combinations of available pest management practices.Methods: To test the efficacy of the three Integrated Pest Management Modules (IPM modules) control vs. treated trees were tagged and then mango mealy bug number found in inflorescence was counted. The difference in the number of mealy bug at the peak time infestation (12 SMW) in control vs. treated trees and fruit loss reduction in control vs. treated plants gave the idea about relative efficacy of the different modules.Result: 99.46% of mango mealy bug number and 47.52% fruit drop reduction were achieved by adopting module I. Whereas up to 64.33% mealy bug and 22.84% fruit drop reduction was achieved by module II. The module III was found to be the most effective module and adoption of this module attained 54.72% fruit loss control and 97.10% mealy bug control.