News Update on stink bugs April-21

[1] Soybean seed damage by different species of stink bugs

Damage caused by the three main species of stink bugs occurring on soybean Nezara viridula (Linnaeus), Piezodorus guildinii (Westwood) and Euschistus heros (Fabricius) was compared in field cages and in greenhouses. Infestation levels of 4 stink bugs/m row of plants (field cages) and 2 stink bug/plant (greenhouse) for 15 days during the pod filling stage are reported. At harvest, the yield and seed quality were evaluated. In the field, there was no difference in yield between infested and insect‐free plants, but damage to seed quality varied with stink bug species. Plants damaged by P. guildinii had the lowest quality seeds. From 50 g seed samples harvested in the field, the mean weight of seeds classified as ‘good’ was 37.3 g in plants infested with P. guildinii, compared to 41.8, 44.2 and 46.6 g in plants infested with E. heros, N. viridula and the control, respectively.

[2] Seasonal Occurrence and Host Spectrum of Egg Parasitoids Associated with Soybean Stink Bugs

In surveys conducted in soybean fields of Northern Parana State, Brazil, 20 species of microhymenopterous parasitoids were observed as egg parasitoids of stink bugs, mainly represented by the families Scelionidae, Encyrtidae, Eurytomidae, and Pteromalidae. When total parasitized eggs were considered for each host species, Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead were the most frequent and prevalent species, with Tr. basalis being preferentially associated with Nezara viridula (Linnaeus) (98%) and Piezodorus guildinii (Westwood) (44%), while Te. podisi was more prevalent on eggs of Euschistus heros (Fabricius) (73%), Podisus connexivus Bergroth (61%), and Dichelops melacanthus (Dallas) (50%). The parasitoids Gryon obesum Masner from eggs of N. viridula and Eu. heros and Trissolcus urichi (Crawford) from eggs of Edessa meditabunda (Fabricius), Eu. heros, and Thyanta perditor (Fabricius) mere recovered for the first time in Brazil.

[3] Characteristics of Home Invasion by the Brown Marmorated Stink Bug (Hemiptera: Pentatomidae)

The abundance and activity of brown marmorated stink bugs, Halyomorpha halys Stål, over-wintering inside a Maryland home were documented. Brown marmorated stink bugs, an invasive species, were collected daily, and their collection rate assessed with respect to outside temperature, location within the structure, and date. During the 181-day study period 26,205 adult brown marmorated stink bugs were collected inside the home. The exiting of stink bugs from hiding in the walls and other suitable areas into indoor living space was positively correlated with outside daily high temperature variation from the long-term daily high. Control measures to block exit from walls into living space reduced collection rate, but failed to halt it. This heavy infestation in a single home demonstrates the potential nuisance to millions of homes across the country if the range and population of the brown marmorated stink bug continues to expand.

[4] Strategy for Insect Pest Control in Cocoa

Farming systems in cocoa over the last three decades have involved the use of new hybrid plant varieties, which produce pods throughout the year, intensified fertilizer use, and misguided pesticide applications by some farmers. Resource availability in terms of abundance of feeding and breeding sites and ecological disruption as a consequence of climate change and bad agronomic practices have increased the importance of insect pests on cocoa. Historically the major management tool for hemipteran pests has been calendar spraying with conventional insecticides. Considerable progress was made at the turn of the last century by replacing organochlorine insecticides for cocoa mirid control. But inappropriate timing and inefficient application is probably reducing the viability of otherwise acceptable products in some areas. Integrated Pest Management (IPM) strategy for mirids and other insect control should involve great investment in pest surveillance, and be based primarily on the use of cultural practices of removal of excess chupons, shade management and host variety resistance. These practices must primarily aim at minimising mirid-associated dieback disease and stink bug deformation of pods, and should be supplemented in some cases by the use of insecticides (up to two applications in February to May at 28-days intervals) depending on the pest populations, damage levels as well as intensity of activity of pollinating insects, with additional two applications during September to December when pest problems may arise. Improved methods of monitoring and prediction should assist in early identification of specific problems in different farms. The rotational use of different active ingredients should also take into account factors such as application methods, compatibility and correct timing. Careful planning is necessary to formulate a flexible control system.

[5] Preliminary Ecological Studies of Insect Species Associated with Different Accessions of Eggplant (Solanum melongena L.) in Southern Ghana

Aims: To determine the relative abundance and diversity of insects on twenty-two accessions of eggplants, as a guide to instituting control measures against unacceptable damage of egg plants grown under field conditions in the Coastal Savannah agro-ecological zone of Ghana.

Study Design: The experimental treatments were deployed in a Randomized Complete Block Design (RCBD), replicated three times.

Place and Duration of Study: Nuclear Agriculture Research Center (NARC) farms and the laboratories of Radiation Entomology and Pest Management Center (REPMC) of Biotechnology and Nuclear Agriculture Research Institute (BNARI), between September 2012 and November 2012.

Methodology: The fields were divided into three replicates each containing twenty-two different accessions of eggplant S. macrocarpon, S. gilio GH8769, S. aethiopicum, S. gilio GH8771,  Nroroye F, Ntorewa K, S. gilio GH8770, S. melongena GH 3949, Ntropo B, Ndroshye E, Ndroshye C, Ndroshye, Nroroye A, Black beauty, Nroroye G, Ntropo K, Ntropo I, Sammy, Ntropo G, Nroroye D, Ntropo H, Nroroye J. The seeds were sown in a nursery and transplanted 35 days after germination to an experimental plot measuring 40 m x 11.4 m in the centre of one acre area so that the experimental plot was surrounded by a homogeneously managed terrain. The experimental treatments were deployed in a Randomized Complete Block Design (RCBD), replicated three times. Each replicate was allotted a plot size of 19.8 m x 8.4 m. Each sub-plot planted to one accession consisting of 22 plants at a spacing of 0.9 m x 0.6 m. Plots were separated by a distance of 2 m. Random sampling technique was used on weekly basis to study the relative abundance, diversity and behaviour of the insect species on the accessions.

Results: Fifteen different insect species were identified on the twenty two accessions of eggplant from the vegetative through to the maturity stage. These comprised three beneficial insects (C. lunata, Camponotus sp. and M. religiosa) and twelve pests (A. craccivora, B. tabaci, B. invadens, Dysdercus sp., G. compestris, L. orbonalis, P. mali, Podagrica sp., O. virudulus, N. viridulus, Phenacoccus sp. and Z. variegatus). Their relative abundance ranged from 0.20– 8.78% for beneficial insects and 0.03 – 45.63% for pests. The highest abundance of insects were found on the accessions Ndroshye (14.09%) and Nroroye G (9.80%). Nroroye F registered the highest diversity of insect species, while Ntropo B and Sammy recorded the least diversity.

Conclusion: There was high abundance of insect species (65.85%) on the field of study. High diversity of insect species was noted and this could be a guide in instituting control measure before pest numbers go beyond the economic thresh-hold level.

 

Reference

[1] Corrêa‐Ferreira, B.S. and De Azevedo, J., 2002. Soybean seed damage by different species of stink bugs. Agricultural and Forest Entomology4(2), pp.145-150.

[2] Correaferreira, B.S. and Moscardi, F., 1995. Seasonal occurrence and host spectrum of egg parasitoids associated with soybean stink bugs. Biological Control5(2), pp.196-202.

[3] Inkley, D.B., 2012. Characteristics of home invasion by the brown marmorated stink bug (Hemiptera: Pentatomidae). Journal of entomological science47(2), pp.125-130.

[4] Adu-Acheampong, R., Sarfo, J.E., Appiah, E.F., Nkansah, A., Awudzi, G., Obeng, E., Tagbor, P. and Sem, R., 2015. Strategy for insect pest control in cocoa. Journal of Experimental Agriculture International, pp.416-423.

[5] Ofori, E.S.K., Afful, N., Quartey, E.K., Osae, M. and Amoatey, H.M., 2015. Preliminary Ecological Studies of Insect Species Associated with Different Accessions of Eggplant (Solanum melongena L.) in Southern Ghana. Journal of Agriculture and Ecology Research International, pp.199-210.

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