Determination of the Critical Period of Cyper-diforce® Treatment against Arthropod fauna and Productivity of Watermelon

Abstract

Watermelon has been reported to be vulnerable to insect pest pressure throughout its growth stages with a resultant indiscriminate calendar-based insecticide application (of up to 25 sprays/season in the study area), with its attendant consequences. In order to recommend the crop growth period(s) to effect chemical control measures that will give better return on investment, field trials were set-up in the early- and late-cropping seasons of 2016 and 2017. Forty, 5m long x 8m wide plots were demarcated in randomized complete block design in 4 replications. Treatments were applications of 0.5% Cyper-diforce® (Cypermethrin 30g/L + Dimethoate 250g/L) at seedling, mid-vegetative, mid-flowering, mid-fruiting stages and their combinations. Unsprayed plots served as control. Pest and beneficial arthropod density, leaf injury, crop growth and yield data were collected and subjected to variance analysis and significantly different means were separated by SNK at 5% level of probability. Cost:benefit ratios of the various treatments was also computed. Findings indicate that, leaf-eating beetles had the highest impact on stand survival and yield. Insect pest density and damage generally decreased with increase in frequency of insecticide application and treatment differences were significant (p< 0.05) except in the case of A. gossypii in the late-sown crop of 2017. Plot sprayed at seedling + vegetative + fruiting stages gave the highest fruit yield and return on investment. It is therefore suggested that, for economic production of watermelon, the crop should not be sprayed during the flowering period.

Effect of Temperature on the Competitiveness of Three Stored Product Insects

“…These data also revealed that an increase in the storage period does not necessarily lead to an increase in population density. The environmental impact on insects when they compete, it becomes clear that the difference in the population density occurs as a result of the positive or negative effect of temperature and for different periods (Okrikata and Ogunwolu, 2019). A study of the biology of T. granarium described its survival as an invasive species, finding that temperature seriously affects population growth.…”

Interactive Effects of Major Insect Pest of Watermelon on its Yield in Wukari, Nigeria

“…Additionally, to suppress the impact of pathogen and weed pests; a broad spectrum preventive fungicide; Mancozeb 80% WP. (Zeb-care ® ) which has a contact mode of action was applied at the rate of 2 kgha -1 at the vegetative, flowering and fruiting stages and, when necessary, weeding was done manually following the method described by Okrikata and Ogunwolu 14 .…”

“…were sampled using a 15 x 15cm yellow sticky board waved across the 5 m length of the middle row of each plot on shaking the plants as described by Okrikata and Ogunwolu 14 . Estimates of population density of aphids (Aphis gossypii Glove) were made by assessing the colony size on 12 randomly selected leaves/plot using a scale from 0 -9 as described by Okrikata nad Ogunwolu 14 . Similarly, fruits infested by fruit fly were isolated and counted in each plot.…”

“…Similarly, fruits infested by fruit fly were isolated and counted in each plot. Infested fruits were split open and the number of fruit fly larvae therein counted and expressed as number of fruit fly larvae/fruit as also described by Okrikata and Ogunwolu 14 .…”