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The ability of a natural enemy to tolerate a wide temperature range is a critical factor in the evaluation of its suitability as a biological control agent. In the current study, temperature-dependent development of the two-spotted ladybeetle A. bipunctata L. (Coleoptera: Coccinellidae) was evaluated on Myzus persicae (Sulzer) (Hemiptera: Aphididae) and a factitious food consisting of moist bee pollen and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs under six constant temperatures ranging from 15 to 35° C. On both diets, the developmental rate of A. bipunctata showed a positive linear relationship with temperature in the range of 15–30° C, but the ladybird failed to develop to the adult stage at 35° C. Total immature mortality in the temperature range of 15–30° C ranged from 24.30–69.40% and 40.47–76.15% on the aphid prey and factitious food, respectively. One linear and two nonlinear models were fitted to the data. The linear model successfully predicted the lower developmental thresholds and thermal constants of the predator. The non-linear models of Lactin and Brière overestimated the upper developmental thresholds of A. bipunctata on both diets. Furthermore, in some cases, there were marked differences among models in estimates of the lower developmental threshold (tmin). Depending on the model, tmin values for total development ranged from 10.06 to 10.47° C and from 9.39 to 11.31° C on M. persicae and factitious food, respectively. Similar thermal constants of 267.9DD (on the aphid diet) and 266.3DD (on the factitious food) were calculated for the total development of A. bipunctata, indicating the nutritional value of the factitious food.

The alfalfa root weevil, Sitona discoideus (Coleoptera: Curculionidae), is an important pest of alfalfa. The developmental rates of the embryo development were recorded at eight constant temperatures ranging from 8.5 to 30 degrees C. Using 10 models (1 linear and 9 nonlinear), we evaluated the relationship between constant temperature and developmental rate. Embryo development was shortest (8.5 d) and longest (69 d), at 28 and 8.5 degrees C, respectively. The threshold temperature (T0) and the thermal constant (K) were estimated using linear regression to be 4.7 degrees C and 207.7 DD, respectively. The two most efficient nonlinear models, the Lactin and the Sharp and DeMichele, gave estimates of Tmin and Tmax of 4.4 and 3.9 and 30.0 and 30.9 degrees C, respectively. This information has potential application in predicting the suitability and optimal time of release of an egg parasitoid of S. discoideus.

The rice stem borer, Chilo suppressalis (Walker), feeds almost exclusively in paddy fields in most regions of the world. The study of its spatial distribution is fundamental for designing correct control strategies, improving sampling procedures, and adopting precise agricultural techniques. Field experiments were conducted during 2011 and 2012 to estimate the spatial distribution pattern of the overwintering larvae. Data were analyzed using five distribution indices and two regression models (Taylor and Iwao). All of the indices and Taylor's model indicated random spatial distribution pattern of the rice stem borer overwintering larvae. Iwao's patchiness regression was inappropriate for our data as shown by the non-homogeneity of variance, whereas Taylor's power law fitted the data well. The coefficients of Taylor's power law for a combined 2 years of data were a = -0.1118, b = 0.9202 ± 0.02, and r (2) = 96.81. Taylor's power law parameters were used to compute minimum sample size needed to estimate populations at three fixed precision levels, 5, 10, and 25% at 0.05 probabilities. Results based on this equation parameters suggesting that minimum sample sizes needed for a precision level of 0.25 were 74 and 20 rice stubble for rice stem borer larvae when the average larvae is near 0.10 and 0.20 larvae per rice stubble, respectively.

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