Faunistic analysis and seasonal fluctuation of ladybeetles in an agro-ecological system installed for organic vegetable production

Plans for an agro-ecological system for agricultural production must consider vegetal diversification in agricultural properties because, among other advantages, it can help the biological control of pests when it focuses on such an end. Predator ladybeetles (Coleoptera: Coccinellidae) can be found in different environments; they play an important role in biological control. The aims of the present study were to feature ladybeetle populations through faunistic analysis and determine their fluctuations in an agro-ecological system comprising seven sub-systems subjected to different cultivation systems in Seropédica County, RJ. The experiment was conducted from December/2018 to December/2019 at Módulo de Cultivo Orgânico Intensivo de Hortaliças (MCOIH), which is located at Sistema Integrado de Produção Agroecológica (SIPA). In total, 1,231 adult ladybeetles were captured, distributed into 13 species, 3 genera and 2 tribes of Coccinellidae, which resulted in S (taxon richness) = 19, Shannon-Wiener diversity index (H') = 0.65 (at 0 to 1 scale) and Margalef diversity index (α) = 2.53 (values lower than 2.0 represent low diversity sites). Equitability was low (E = 0.22), since one of the ladybeetle species has prevailed: Cycloneda sanguinea (most frequent, dominating and constant) in MCOIH, as well as in each of the sub-systems. However, the simplest sub-systems installed for vegetable production (monoculture gardens) were not favorable for ladybeetle diversity, whereas sub-systems installed for polyculture of leafy vegetables recorded the greatest taxa diversity of ladybeetles, including species that predate in aphids that attack vegetables [Coleomegilla maculata, Coleomegilla quadrifasciata, Cycloneda sanguinea, Eriopis connexa, Harmonia axyridis, Hippodamia convergens and Hyperaspis (Hyperaspis) festiva]. The sub-system comprising gliricidia was used to produce fertilization biomass and favored the predominance of C. sanguinea in comparison to the other ladybeetle species in MCOIH. Spring was the season mostly favoring the occurrence of C. sanguinea and H. convergens adults; which were dominant species in ladybeetle assemblage in MCOIH; however, C. sanguinea was constant and H. convergens was accessory.

Influence of the amount of food resources in the foraging behavior of Nasutitermes corniger (Motschulsky) / Influência da quantidade de madeira no comportamento de forrageamento de Nasutitermes corniger (Motschulsky)

Food scarcity or abundance are factors regulating termites' foraging behavior in general. The aim of the present study is to evaluate the influence of four amounts of Eucalyptus grandis on foraging behavior events shown by worker and soldier of Nasutitermes corniger during laboratory tests. The tests were carried out with adult and active N. corniger colonies found in nests collected in the field, which were stored in glass cubes connected to the test arenas. Four different amounts of wood blocks were used in the tests and each amount concerned a treatment and defined a different experimental group: 1, 2, 3 and 4 blocks/arenas, with 5 repetitions. Each test lasted 60 minutes and consisted in observing, or not, the occurrence of behavioral events shown by foragers when they had contact with the treatment. The duration of each event was recorded, whenever it was observed. The number of recruited foragers and the number of workers consuming the blocks were recorded at the end of each test applied to each treatment. Nasutitermes corniger presented the three behavioral events in all treatments; however, there was not significant difference between treatments in the occurrence of the two first events, in the time taken from test start to the occurrence of a new event, in the number of recruited termites and in the number of gnawing workers. Only workers' mass recruiting was influenced by the amount of wood available. The occurrence of this event was significantly higher in treatments with greater amounts of wood. Thus, N. corniger adjusts its mass recruitment behavior in response to available food amount, which should be considered when developing baiting system for its control. (AU)

A escassez ou abundância de alimento são fatores que regulam o forrageamento do térmitas em geral. No presente estudo, avaliou-se a influência de quatro quantidades de madeira de Eucalyptus grandis em eventos comportamentais do forrageamento exibidos por operárias e soldados de Nasutitermes corniger em testes de laboratório. Os testes foram realizados com colônias maduras e ativas de N. cornigerpresentes em ninhos coletados a campo, os quais foram acondicionados em cubas de vidro conectadas a arenas testes. Blocos de madeira de mesma dimensão foram ofertados aos térmitas em quatro quantidades: 1, 2, 3 e 4 blocos/arena, com 5 repetições. Cada teste durou 60 minutos e consistiu na observação ou não da ocorrência de eventos comportamentais exibidos pelos forrageadores quando foi dado acesso a cada tratamento. Quando cada evento foi observado, o tempo de sua duração foi registrado. Ao final de cada teste registrou-se, em cada tratamento, o número de térmitas forrageadores recrutados e o número de operários consumindo os blocos. Observou-se que N. corniger exibiu os três eventos comportamentais em todos os tratamentos. Todavia, não houve diferença significativa entre os tratamentos com relação à ocorrência dos dois primeiros eventos, aos tempos transcorridos desde o início do teste até a ocorrência de cada evento, aos números de térmitas recrutados e ao número de operários em roedura. Apenas a ocorrência de recrutamento em massa dos operários foi influenciada pela quantidade de madeira ofertada, sendo que foi significativamente superior quando se ofertou os blocos de madeira na maior quantidade. Dessa forma, N. corniger ajusta seu comportamento de recrutamento em massa em resposta a quantidade de alimento disponível, o que deve ser considerado ao se desenvolver um sistema de isca para seu controle. (AU)