Effect of abiotic and biotic factors on incidence of pests and predator in cowpea[Vigna unguiculata(L.) walp.]

Abstract

Field experiments were conducted during Kharif season of 2007-2008. The pest population was recorded in cowpea field aphids, jassid, thrips and pod borer and its highest population 116.20/15 cm shoots tip, 8.6/compound leaves, 5.87/flower bud and 0.73/flower bud and 1.8/pod, respectively. Abiotic factors like temperature, relative humidity, extent and distribution of rainfall, sunshine hour etc. influenced the infestation and stabilization of various insect pests in cowpea. The populations of aphids and pod borer influenced positively relative humidity while those of jassid was affected by temperature and sunshine hour. The negative correlation was found between aphid and maximum temperature, sunshine hour and wind speed; jassid and thrips with relative humidity and pod borer with maximum temperature and wind speed. Coccinella septempunctata was the most abundant predator of cowpea aphid and negatively correlated with aphid population.

Seasonal Incidence of Major Insect Pests of Cowpea in Relation to Biotic and Abiotic Factors

“…These finding are in conformity with Kumar et al, (2015) reported that Thrips (Megalurothripssjostedti Tryb.) population was observed in last week of September and its highest population was recorded in third week of October (5.87/flower bud).…”

“…Weekly observations on major insect pest population available in the experimental field were recorded on randomly selected five plants from experimental plots during the whole cropping season i.e. from September 2015 to December 2015.The method modified as according to (Jackai, 1982;Kumar and Kumar, 2015). Correlation analysis was worked out as per method given by Gomez and Gomez (1984).…”

Spatially Differentiated Trends between Forest Pest-Induced Losses and Measures for Their Control in China

“…Pests under the strongest control pressure in the east are Bursaphelenchus xylophilus, Hyphantria cunea, and Mikania micrantha, while in the west, the most pressured pests are forest pikas [17,18]. As a result of the threat of global warming, and the pressure from economic development from southeast to northwest, transportation has carried along invasive pests that are spreading rapidly across regions with suitable environments and fewer natural enemies [19][20][21]. As this trend continues, even the unsuitable environment of the northwest now has more forest pests, while the lower capacity for the control of potential damage in the region places a heavier burden on local governments to take the necessary measures to control this potentially disastrous situation.…”

“…The government has already established a forest pest-control system via the State Forest Administration with a primary level consisting of forest quarantine or monitoring stations and other cooperative organizations for the prevention of pest outbreaks [44]. However, overall, the burden of control is carried out by the primary forest stations in the counties with weaker infrastructures, and the funds are mostly input by the local governments, triggering an extremely unjust imbalance in the control measures in each province, even when considering the "Hu line" distribution regularities [19][20][21]. In particular, after Premier Li Keqiang stated that China should break the traditional demographic pattern in order to allow people from all regions to benefit from modernization, the government put forward several policies, such as poverty reduction, ecological construction, and other supports to erase the imbalance barrier of the "Hu line" [45].…”

Estimation of genetic parameters in white seed cowpea (Vigna unguiculata (L) Walp)

“…In Colombia, cowpea is produced by small farmers in the seven departments of the Atlantic coast, due to their adaptation to their climate and soil conditions, as in other tropical and subtropical areas of the world, but their yields are considered low (600 kg ha -1 ) compared to those in the United States and Peru, which yielded 1.790 and 1.376 kg ha -1 in 2014 (FAO, 2017). Low yields are attributed to the use of obsolete varieties and to susceptibility to biotic and abiotic factors, especially drought and high temperatures (Kumar and Kumar, 2015). For Ribeiro et al (2014), the genetic improvement by programs of public entities has allowed to increase the yields and the adaptation to different systems of production.…”