Determination of economic injury level for pod borers of chickpea in dry farms of Ilam province

Chickpea, one of the major pulses, is planted together with wheat as a custom rotation in Ilam province. Pod borers are serious pest of chickpea and their direct damage to seed reduce yield considerably. Annually, farmers use much pesticide against the pest without any clue. In order to determine economic injury level (EIL), a semi-field study was started in 2000 to calculate this parameter based on a complete randomized block design with five treatments and four replications. Emerged larvae in the surrounding chickpea fields were collected and released in cages at the density of 0, 10, 20, 40, 80 larvae per square meter. Various factors (e. g. yield, damaged and total seeds) were measured and analyzed at harvesting time. Results show that if market value of chickpea and cost of management (treatment) are considered 3500 rials per kg and 150000 rials, respectively, then EIL will be 3.9 larvae per square meter (four rows with a length of one meter)

Sequential sampling of overwintered sunn pest, Eurygaster integriceps (Het.: Scutelleridae) in rainfed wheat fields in Borujerd, Iran

The sunn pest, Eurygaster integriceps Puton, is the most important pest of wheat and barley in most wheat producing regions of Iran, including Lorestan province. The pest overwinters under bushes in mountains and returns to wheat fields in the next spring. Study of spatial distribution of overwintered sunn pest (OSP) in rainfed wheat fields using two quadrate sizes (50 à 50 cm2 = 0.25 m2 and 70.71 à 70.71 cm2 = 0.5 m2) and their conformity with negative binomial distribution, showed a dispersion pattern of aggregation. In this study, a sequential sampling plan (Waldâs method) was presented by use of 1.5 OSP/m2 as an action threshold and 1.05 OSP/m2 as the safety level, and estimating the common K (Kc) for the both sizes of quadrates in 2004 and 2005. Two sizes of quadrates were used as sample units to estimate densities and dispersion patterns of the pest populations. The decision lines, y = 0.32x ± 7.62 andy = 0.63x ± 7.44 were calculated for 0.25 and 0.5 m2 quadrates, respectively. The operating characteristic (OC) and average sample number (ASN) curves indicated that low numbers of samples are required for control decision making when the population densities are either low (less than 0.22 and 0.44 OSP/q for small and large quadrates, respectively) or high (more than 0.45 and 0.89 OSP/q for small and large quadrates, respectively). However, the number of samples required will be high when the population density is nearly medium and at the point of inflection of OC curve (0.32 and 0.63 OSP/q for small and large quadrates, respectively)