Responses of nematode abundances to increased and reduced rainfall under field conditions : a meta-analysis

Ecosystems are projected to experience altered precipitation patterns associated with climate change, with some areas becoming wetter and others drier. Both above- and belowground communities will be impacted by such rainfall changes, yet research has predominantly focused on the flora and fauna aboveground. Still, there is a growing body of literature for the effects of altered precipitation on soil fauna. Nematodes are diverse and abundant in most soils, represent multiple trophic levels, and influence essential soil processes, making this group a good proxy for broader impacts on soil food webs. Hence, we assessed the effects of increased and reduced rainfall amount on total and trophic-level abundances of nematodes using a meta-analytical approach based on 46 independent observations from 37 field studies and tested whether effects differed among ecosystem types and with treatment duration (1 year, long term). Overall, total and trophic group's abundances, except fungal feeders, were negatively impacted by reduced rainfall irrespectively of treatment duration. Increased rainfall had a positive effect on total abundances and plant parasitic nematodes, but only in longer term studies (>1 year). The impacts of altered rainfall were consistent across the ecosystems studied; however, most studies focus on grasslands and deserts, making it difficult to draw broad generalizations. Reductions in rainfall are therefore likely to decrease soil nematode abundance, with less pronounced effects on fungal feeders. Increased rainfall, on the other hand, may favor plant parasites, likely due to increased plant productivity. Hence, projections of reduced rainfall will have significant negative impacts on nematode abundances, at least in grasslands and deserts, with cascading effects on soil processes

First report of litchi stink bug (Tessaratoma javanica Thunberg) outbreak in Bangladesh

Litchi growers reported the infestation of an unknown insect pest recently in the north-eastern part of Bangladesh, which affected litchi production remarkably. A field survey was conducted to identify this invasive insect species, and the biology of this insect was studied under laboratory conditions. Further, damage severity of the insect was determined in the affected litchi orchards. Based on morphological features, the invasive species was identified as litchi stink bug, Tessaratoma javanica (Thunberg) (Hemiptera: Tessaratomidae). Female stink bugs laid eggs in clusters (2.0) either upper or lower surface of both mature and young litchi leaves. After egg hatching, nymphs completed five distinct instars before reaching to adults. Longevity of adult litchi stink bug varied on sex types, while females lived longer than males. The level of litchi stink bug infestation varied greatly in the survey areas. The infestation of stink bug did not find in all inflorescence of the attacked plants. Significantly decreased fruits were recorded in the infested inflorescence. This study firstly confirm the invasion of litchi stink bug in Bangladesh, and this information would help scientist to develop IPM strategies against this destructive stink bug species using available resources

Practices of entomophagy and entomotherapy in Bangladesh

Aspects of entomophagy and entomotherapy of ethnic people in Bangladesh are documented as this practice is believed to ensure future food security. A comprehensive survey was conducted involving six insect-consuming ethnic groups: Garo, Chakma, Tanchangya, Marma, Mro, and Tripura. A total of 36 insect species of 19 families and 7 orders were consumed by them. In terms of species, those of the Coleoptera ranked highest (14), followed by Hymenoptera (7), Orthoptera (5), Hemiptera (5) and Blattodea (3 species); one species each belonged to Ephemeroptera and Odonata. The field cricket (Brachytrupes sp.), short-horned grasshopper (Oxya sp.) and giant water bug (Lethocerus indicus) were most preferred, reaching respective acceptance levels of 84, 83, and 79% by the respondents of all ethnic groups taken together. The total number of species used as human food by the Chakma, Marma, Mro, Tanchangya, Tripura, and Garo was 32, 22, 29, 21, 26, and 14, respectively. Nine species were used to treat coughs, fevers, nocturnal emissions, burning and gastroenteritis. People gathered the insects mainly from the insects’ natural habitat and consumed them as snacks or part of a meal. The availability of edible insects depended on the season. Despite consumer demand, insect consumption is decreasing, apparently due to the unavailability of insects because of the random application of pesticides and fertilisers. The top three entomophagy constraints include lack of knowledge to farm insects, to harvest them, and to effectively store and preserve them. By overcoming these constraints, practices of entomophagy might play additional role in increasing future food security in Bangladesh through developing edible insect industry