H. H. Toba

Gamma irradiation: Effect of dose and dose rate on development of mature codling moth larvae and adult eclosion

Abstract Codling moth, Cydia pomonella (L.), larvae infest apples, pears and many other fruits and nuts. Mature, nondiapausing, cocooned larvae in fiberboard strips were exposed to γ-irradiation at applied doses ranging from 0 to 98 Gy and dose rates from 0.77 to 204.4 Gy/min and subsequently held to permit further development, pupation and adult emergence. At or above an applied dose of 58 Gy, many of the adults that emerged were physically deformed and most were males. As the applied dose increased from 44 to 98 Gy, the percentage of normal adults decreased, the primary effect shifting from a higher percentage of abnormal adults, pupal mortality, to larval mortility. The effects were more pronounced at higher than at lower dose rates. Insect development apparently was not affected when larvae were irradiated at applied doses up to 31.7 Gy. Significantly more adults emerged when larvae were treated at low dose rates (1.0 Gy/min) than at higher dose rates (204 Gy/min). A rate of 52.2 Gy/min was more effective at preventing adult emergence than rates of 1, 4.4 or 201.5 Gy/min.

Relationship between injury and damage to potatoes by wireworms

A relationship between injury (any penetration of a tuber) and damage (in accordance with the U.S. Standards for Grades of Potatoes) caused by the sugarbeet wireworm,Limonius californicus (Mannerheim), the Pacific Coast wireworm,L. canus LeConte, and the Great Basin wireworm,Ctenicera priunina (Horn), to potatoes was determined. Based on tuber weights, the percentage of damage (D) increased curvilinearly with increased percentage of injury (I). Percentages of injured and damaged tubers based on tuber weights were significantly different from those based on tuber count. Difference in the relationship of injury vs. damage between untreated and fonofos-treated tubers was not significant. The regression D = -0.012 + 0.1 111 + 0.003I2 can be used to estimate the amount of damage from the amount of injury without the necessity of cutting and measuring feeding holes.ResumenSe determinó en papa una relación entre las heridas (cualquier penetración en el tubérculo) y los danos (según están definidos en al “U.S. Standards for Grades of Potatoes) causados por el gusano alambre de la remolacha (Limonius californicus Mannerheim), por el gusano alambre de la costa del Pacífico (L. canus LeConte), y por el gusano alambre de la Gran Cuenca (Ctenicera pruinina Horn). Basándose en el peso de los tubérculos, se observó que el porcentaje de daños (D) se incrementó en función curvilínea con el aumento del porcentaje de heridas (H). Cuando los porcentajes de tubérculos con heridas y con daños se obtuvieron basándose en el peso de los tubérculos, éstos fueron significativamente diferentes a los basados en el conteo de los mismos. La relación entre heridas y daños en tubérculos sin tratar y en tubérculos con “fonofos” no presentó diferencia significativa. Le ecucación de regresión D = -0.012 + 0.111H + 0.003H2 puede ser utilizada para estimar la cantidad de daños (D) utilizando la cantidad de heridas (H) sin necesidad de cortar y medir los orificios de alimentación.