Factors affecting colonization and abundance of Aphis gossypii glover (hemiptera: aphididae) on okra plantations

Abstract

The control of Aphis gossypii Glover (Hemiptera: Aphididae) on okra Abelmoschus esculentus (L.) (Malvaceae) consist primarily in the use of insecticides, due to the lack of information on other mortality factors. The objective of this study was to determine the effects of predators and parasitoids, height of canopy, plant age, leaf areas, organic compounds leaves, levels of leaf nitrogen and potassium, density of leaf trichomes, total rainfall and median temperature on attack intensity of A. gossypii on two successive A. esculentus var. Santa Cruz plantations. Monthly number estimates of A. gossypii and natural enemies (visual inspection) occurred on bottom, middle and apical parts of 30 plants/plantation (one leaf/plant). Plants senescence, leaf areas and natural enemies, mainly Adialytus spp., spiders and Coccinellidae, were some of the factors that most contributed to aphid reduction. A higher number of aphids was found on the bottom part than medium and apical parts of okra plants. Total rainfall can reduce the aphid population. Trichomes non-glandular or low density, organic compounds leaves and levels of N and K were not important for reducing aphid population.Index terms: Abelmoschus esculentus, aphid, natural enemies, leaf area, nitrogen. RESUMOO controle de Aphis gossypii Glover (Hemiptera: Aphididae) em quiabeiro Abelmoschus esculentus (L.) (Malvaceae) consiste principalmente no uso de inseticidas, em virtude da falta de informação sobre outros fatores de mortalidade. Objetivou-se com este estudo determinar os efeitos de predadores e parasitóides, altura de dossel, idade da planta, área foliar, compostos orgânicos foliares, níveis de nitrogênio e potássio, densidade de tricomas, pluviosidade e temperatura na intensidade de ataque de A. gossypii em dois cultivos sucessivos de Abelmoschus esculentus var. Santa Cruz. Estimou-se, mensalmente, o número de A. gossypii e de inimigos naturais (inspeção visual) ocorridos nas folhas (uma folha/planta) localizadas nas partes basal, mediana e apical de 30 plantas/ plantação. Os fatores que mais contribuíram com a redução da população de pulgões foram a senescência de plantas, área foliar e inimigos naturais, principalmente Adialytus spp., aranhas e Coccinellidae. Maior número de pulgões foi observado na parte basal que na mediana e apical de plantas de quiabeiro. A pluviosidade total pode reduzir a população de pulgões. Tricomas tectores (não-glandulares) ou baixa densidade destes, compostos orgânicos foliares e níveis de N e de K não foram importantes para a redução da população de pulgões. Termos para indexação:Abelmoschus esculentus, afídeos, inimigos naturais, área foliar, nitrogênio.

Deleterious Activity of Natural Products on Postures of Spodoptera frugiperda (Lepidoptera: Noctuidae) and Diatraea saccharalis (Lepidoptera: Pyralidae)

“…However, the effi ciency of botanic products on insects might vary with UV radiation, temperature, and solvent used, or with the concentration of the extract (Moreira et al, 2007). The genetics of the plant, the extraction time of the compounds (Sidhu et al, 2004), leaf areas, organic compounds of leaves, density of leaf trichomes (Leite et al, 2007), and the part of the plant used for producing the extracts further infl uence the activity of some compounds against insects (Siskos et al, 2007). In addition this product is more effi cient in the fi eld, since it activates substances of the secondary metabolism of the plants and thus improving resistance (Tsuzuki et al, 2000).…”

Harmonia axyridis: a threat to Brazilian Coccinellidae?

“…Standl. (Peronti & Souza-Silva 2002), Sechium edule Swartz (Neupane et al 2006), Cucumis sativus L. (Steenis & El-Khawass 1995), Cucumis melo L. (Kingler et al 1998) and Abelmoschus esculentus (L.) Moench (Leite et al 2007).…”

Ant attendance of the cotton aphid is beneficial for okra plants: deciphering multitrophic interactions

“…Okra ( Abelmoschus esculentus Moench) is an economically important vegetable crop grown worldwide and is widely consumed in West Africa. In Cameroon, the cotton aphid ( Aphis gossypii Glover) is one of the dominant pests of okra (Leite et al ., ; Shannag et al ., ) and has evolved resistance to pesticides, particularly on cotton plant (Brévault et al ., ). An annual survey conducted by the International Institute of Tropical Agriculture (IITA) in Cameroon (2011) found that okra farmers grow many different okra varieties, various ant species attend aphids on okra, and ants of genus Pheidole were the dominant ant species found attending aphids on okra plants in 75% of the surveyed okra farms (IITA annual survey report, 2011).…”