Efeito da solarização e da adubação sobre artrópodes em solo cultivado com alface Solarization, organic and chemical fertilization combined effects on arthropods community in soil cultivated with lettuce

Avaliou-se o efeito da solarização e da adubação química e orgânica na comunidade de artrópodes de solo na cultura da alface, cv. Verônica. Foram conduzidos dois experimentos, em blocos ao acaso, um com solarização e o outro sem solarização, em casa de vegetação, ambos com cinco tratamentos: adubação orgânica; nitrogênio na forma amoniacal (NH4); adubação com NPK; adubação orgânica + NPK; testemunha (sem adubação). No experimento solarizado, o solo foi coberto durante 132 dias com plástico transparente. Os artrópodes foram coletados por meio de armadilhas tipo alçapão em três épocas (antes da implantação do experimento, após a solarização e após a colheita). Foram utilizados índices faunísticos e de diversidade em cada experimento, tratamento e épocas. Os principais grupos coletados foram: Collembola (82,8%), Acari (7,1%), Hymenoptera (6,1%) Coleoptera (1,3%) e outros (2,7%). A classe Collembola foi a mais abundante, mesmo na colheita, quando a subordem Acari aumentou substancialmente. As espécies de Collembola predominantes foram: Proisotoma tenella (Reuter) (34,3%); Seira atrolutea (Arlé) (29%); Folsomides centralis (Denis) (7,2%); Isotomurus sp. 161 (2,4%) e Sminthurides sp. 98 (1,6%). Observou-se que a diversidade e abundância da comunidade de artrópodes não foi influenciada pela solarização ou adubação.<br>To evaluate the effect of solarization, chemical and organic fertilization on soil arthropods community in lettuce, two blocks plots trials were carried out in Brasília, Brazil. One research was conducted with solarization and the other without solarization in a soil cultivated with lettuce, cv Veronica, under protected cultivation. Each trial consisted of five fertilization treatments: T1= organic fertilization; T2= amoniacal nitrogen (ammonium sulphate); T3= chemical fertilization; T4= organic and chemical fertilization; T5= control (without fertilization). In the solarized trial, the soil was covered for 132 days with transparent plastic. The arthropods were collected by pitfalls at three moments: 1) before solarization, 2) after solarization and 3) at harvest. Faunistic indexes were calculated in each trial, treatment and moments. The main collected groups were: Collembola (82.8%), Acari (7.1%), Hymenoptera (6.1%), Coleoptera (1.3%) and others (2.7%). Collembola class represented the largest proportion of the arthropods, even at harvest when the sub-order Acari substantially increased. The predominant species of Collembola were: Proisotoma tenella (Reuter) (34.3%); Seira atrolutea (Arlé) (29%); Folsomides centralis (Denis) (7.2%); Isotomurus sp.161 (2.4%) and Sminthurides sp. 98 (1.6%). Arthropods community was not affected by solarization or fertilization

Exploiting chemical ecology for developing novel integrated pest management strategies for Africa

Push-pull, a novel approach for integrated management of insect pests, weed and soil fertility, was developed through the exploitation of chemical ecology and agro-biodiversity to address agricultural constraints facing millions of resource-poor African farmers. The technology was developed by selecting appropriate plants that naturally emit signalling chemicals (semiochemicals) and influence plant-plant and insect-plant interactions. Plants highly attractive for egg laying by lepidopteran cereal stemborer pests were selected and employed as trap crops, to draw pests away from the main cereal crops. Among these, Pennisetum purpureum produced significantly higher levels of volatile cues (stimuli), used by gravid stem borer females to locate host plants, than maize (Zea mays) or sorghum (Sorghum bicolor). Despite its attractiveness to stemborer moths, P. purpureum supported minimal survival of the pests’ immature stages. Plants that repelled stem borer moths, notably Melinis minutiflora and forage legumes in the genus Desmodium, were selected as intercrops, which also attracted natural enemies of the pests through emission of (E)-β-ocimene and (E)-4,8-dimethyl-1,3,7-nonatriene. Desmodium intercrop suppressed parasitic weed, Striga hermonthica, through an allelopathic mechanism. Their root exudates contain novel flavonoid compounds which stimulate suicidal germination of S. hermonthica seeds and dramatically inhibit its attachment to the host roots. We identified and selected new drought- and temperature-tolerant trap [Brachiaria ( B. brizantha × B. ruziziensis ) cv. mulato] and intercrop plants (Desmodium, e.g. D. intortum) suitable for drier agroecologies. The new trap and intercrop plants also have appropriate chemistry in controlling stemborers, a new invasive pest, fall armyworms and parasitic striga weeds. Opportunities for semiochemical delivery by companion plants, including plant-plant signalling and early herbivory alert, are explored for developing future smart integrated pest management (IPM) strategies