Field evaluation of insecticides and non-insecticidal materials against pit scale, Asterolecanium sp. nr. striatum Russell, an invasive insect pest of calamansi in Calapan, Oriental Mindoro [Philippines]
2007
Javier, P.A. | Ceballo, F.A. | Bayot, R.G.
Seven insecticides (thiamethoxam, triazophos, malathion, acetamiprid, cartap and carbaryl) and two non-insecticidal materials (kaolin and mineral oil), which were reported effective/promising against sucking insects were evaluated against pit scale, Asterolecanium sp. nr. striatum Rusell. The pit scale is a new and invasive insect pest, which had reportedly killed many calamansi trees in Calapan City, Oriental Mindoro. Therefore, the study was conducted in Barangay [village] Nag-iba 2, Calapan City. The materials were applied four times at bi-weekly interval, following the Company's recommended dosage. Pit scale insect population was monitored before insecticide application and at two days after each insecticide application using a 1-9 rating scale with 9 having the greatest damage and 1 without any sign of pit borer infestation. The experiment was laid out in randomized complete block design with four replications. Prior to the first spraying, average rating scale was about 6.90, which suggested a very high scale population with an average of 0.50 cm distance between adjacent scales. In general, the mineral oil and kaolin were ineffective against the pit scale with population even higher than that in the control throughout the course of the experiment. With the exception of malathion and thiamethoxam, all insecticide treatments significantly reduced the pit scale population. Among the different insecticidal treatments, triazophos and acetamiprid were the most effective against the pit scale, followed by imidacloprid, carbaryl and cartap. Another trial was envisioned but was not possible due to very low pit scale insect population.
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