Dimitris C. Kontodimas

Comparative Temperature-Dependent Development of Nephus includens (Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae) Preying on Planococcus citri (Risso) (Homoptera: Pseudococcidae): Evaluation of a Linear and Various Nonlinear Models Using Specific Criteria

Abstract The effect of temperature on the development of the predators Nephus includens (Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae) was studied. The duration of the development of immature stages and the pre-oviposition period of the two predators, reared on Planococcus citri (Risso) (Homoptera: Pseudococcidae) at eight constant temperatures (10, 15, 20, 25, 30, 32.5, 35, and 37.5 ± 1°C), have been recorded. The developmental zero (lower temperature threshold) was estimated to be 10.9 and 9.4°C, and the thermal constant was 490.5 and 614.3 DD for N. includens and N. bisignatus, respectively, using the linear model. Data were fitted to various nonlinear temperature-dependent models, and the thermal developmental thresholds (lower and upper), as well as the optimum temperature for development, have been estimated. Evaluation of the models took place, based on the following criteria: fit to data (residual sum of squares and coefficient of determination or coefficient of nonlinear regression), number and biological value of the fitted coefficients, number of measurable parameters, and accuracy on the estimation of the thresholds. Conclusively, linear and Lactin models are highly recommended for the description of temperature-dependent development of these two predators and possibly of other coccinellids.

Establishment ofHarmonia axyridis on Citrus and Some Data on Its Phenology in Greece

In September 1993, a colony ofHarmonia axyridis Pallas (Coleoptera:Coccinellidae) was imported from France into Greece. In 1994, insectary-reared adults were released in 11 citrus orchards in four citrus-growing areas of Greece. Between May 19 and June 8, 1994,H. axyridis was recovered from a total of seven localities in three of these areas. This species was established on orange, mandarin and sour orange trees heavily infested withToxoptera aurantii, Aphis spiraecola andA. gossypii; its absence from the remaining four localities may have been the result of low prey densities. Twenty-three days after the initial releases,H. axyridis larvae comprised 57.9% and 83.3%, respectively, of the aphidophagous coccinellid larval populations in two localities (on Chios Island). In samples taken at Leonidion 43 days after the introduction release, both adult and larval populations ofH. axyridis represented approximately one-third of aphidophagous coccinellid adults and larvae found, whereas the indigenousAdalia bipunctata comprised about one-half of the population. In cages placed outside the Athens laboratory,H. axyridis completed four overlapping generations annually; average longevities of 56.2, 66.8, 78.9 and 102.2 days, respectively, were recorded for the successive generations. Adults of the 3rd and 4th generations overwintered, giving rise to the following year’s 1st generation. Oviposition began in April and emergence of 1st generation adults occurred in mid-May. The egg-laying activity of the females throughout the warm period of the year indicates thatH. axyridis does not diapause in summer. From December until March, small aggregations (2-4 individuals) were observed within the cages at protected sites.

On automatic bioacoustic detection of pests: the cases of Rhynchophorus ferrugineus and Sitophilus oryzae.

ABSTRACT The present work reports research efforts toward development and evaluation of a unified framework for automatic bioacoustic recognition of specific insect pests. Our approach is based on capturing and automatically recognizing the acoustic emission resulting from typical behaviors, e.g., locomotion and feeding, of the target pests. After acquisition the signals are amplified, filtered, parameterized, and classified by advanced machine learning methods on a portable computer. Specifically, we investigate an advanced signal parameterization scheme that relies on variable size signal segmentation. The feature vector computed for each segment of the signal is composed of the dominant harmonic, which carry information about the periodicity of the signal, and the cepstral coefficients, which carry information about the relative distribution of energy among the different spectral sub-bands. This parameterization offers a reliable representation of both the acoustic emissions of the pests of interest and the interferences from the environment. We illustrate the practical significance of our methodology on two specific cases: 1) a devastating pest for palm plantations, namely, Rhynchophorus ferrugineus Olivier and 2) a pest that attacks warehouse stored rice (Oryza sativa L.), the rice weevil, Sitophilus oryzae (L.) (both Coleoptera: Curculionidae, Dryophorinae). These pests are known in many countries around the world and contribute for significant economical loss. The proposed approach led to detection results in real field trials, reaching 99.1% on real-field recordings of R. ferrugineus and 100% for S. oryzae.

Age-Specific Life Table Parameters and Survivorship of an Iranian Population of the Codling Moth (Lepidoptera: Tortricidae) at Different Constant Temperatures

ABSTRACT Age-specific life table parameters and survivorship, adult longevity, reproduction periods, fertility, and sex ratio of the codling moth were studied at eight constant temperatures (10, 14, 20, 25, 27, 30, 33, and 35 ±0.5°C). Among the examined temperatures, the highest values of net reproductive rate, intrinsic rate of increase, and finite rate of increase were 18.28 (females/female), 0.08 (females/female/d), and 1.08 at 27°C, respectively. Similarly, the highest value of sex ratio was 0.56 [females/ (females + males)] at 27°C. The highest mean generation time and doubling time were 72.26 and 23.09 d, respectively, at 20°C. To present a suitable model for intrinsic rate of increase at different temperatures, a nonlinear Lactin model was fitted to our observations. The longest preoviposition period was 2.77 and 2.55 d at 20 and 30°C, respectively. Also, the longest oviposition period was 8.46 d at 20°C. Postoviposition period was not statistically different at examined temperatures. The Weibull frequency distribution was used to describe the age-specific survival of the female adults. Based on the Weibull distribution parameters, the survival curves were type I at all examined temperatures, which indicates that mortality mostly occurred in old individuals. These findings confirmed that temperature is a critical environmental factor affecting codling moth population growth.

Modeling Embryo Development of Sitona discoideus Gyllenhal (Coleoptera: Curculionidae) Under Constant Temperature

Abstract 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°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°C, respectively. The threshold temperature (T0) and the thermal constant (K) were estimated using linear regression to be 4.7°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°C, respectively. This information has potential application in predicting the suitability and optimal time of release of an egg parasitoid of S. discoideus.

Temperature-Dependent Development of Chilocorus bipustulatus (Coleoptera: Coccinellidae)

ABSTRACT The effect of temperature on development and survival of Chilocorus bipustulatus L. (Coleoptera: Coccinellidae), a predator of many scale insects, was studied under laboratory conditions. The duration of development of egg, first, second, third, and fourth larval instars, pupa, and preovioposition period at seven constant temperatures (15, 17.5, 20, 25, 30, 32.5, and 35°C) was measured. Development time decreased significantly with increasing temperature within the range 15–30°C. Survival was higher at medium temperatures (17.5–30°C) in comparison with that at more extreme temperature regimens (15 and >30°C). Egg and first larval instars were the stages where C. bipustulatus suffered the highest mortality levels at all temperatures. The highest survival was recorded when experimental individuals were older than the third larval instar. Thermal requirements of development (developmental thresholds, thermal constant, optimum temperature) of C. bipustulatus were estimated with application of linear and one nonlinear models (Logan I). Upper and lower developmental thresholds ranged between 35.2–37.9 and 11.1–13.0°C, respectively. The optimum temperature for development (where maximum rate of development occurs) was estimated at between 33.6 and 34.7°C. The thermal constant for total development was estimated 474.7 degree-days.

Summer diapause and winter quiescence ofCoccinella septempunctata (Col. Coccinellidae) in central Greece

Coccinella septempunctata (Coleoptera: Coccinellidae) in Greece is a multivoltine species. In the lowlands, all instars are abundant in spring becoming scarce from July until the end of the warm period of the year; they are absent in winter. In June, mostC. septempunctata adults migrate to mountainous aestivo-hibernation sites. Measurements of the duration of pre-oviposition period in females taken monthly from the summit of Mount Kitheron in central Greece (1993–1994) and transferred to laboratory conditions of high temperature (25°C), long day (16 hrs light/24 hrs), and presence of aphids, indicated that theC. septempunctata females were in diapause during July and August. The diapause gradually terminated from late August to late October and was followed by a period of quiescence extending from November to March of the following year.During the summer diapause, arrest of ovarian development was indicated by immaturity of the ovaries in all sampled females and the complete absence of vitellogenic resorption signs. Also, adults were found with enlarged fat bodies, and the median duration of preoviposition period in females transferred to the above laboratory conditions was 90 days in early July and 82 days in early August. During the period of winter quiescence, arrest of ovarian development was characterized in most samples by immaturity of the ovaries in all females and, in some samples, by the presence of a few females with signs of vitellogenic resorption. In winter, adults were found containing fat body reserves of different levels, and the median preoviposition period of females transferred to optimal breeding conditions was 29 days in early November and 16 days in mid January.RésuméCoccinella septempunctata est une espèce multivoltine en Grèce. Le développement actif de tous les stades de développement se déroule au cours du printemps dans les régions basses. Au cours du reste de l’année, les adultes en grande majorité se trouvent en estivo-hivernation aux sommets des montagnes. L’estivo-hivernation des adultes deC. septempunctata provenant du sommet du Mont Kitheron en Grèce centrale passe, successivement, d’une période de diapause, au cours des mois de juillet et août, qui se termine progressivement entre la fin août et la fin octobre, à une période de quiescence hivernale, à partir du mois de novembre jusqu’au mois de mars de l’année suivante.Au cours de la diapause estivale, l’arrêt du développement ovarien a été mis en évidence à travers l’immaturité des ovaires de toutes les femelles et par l’absence complète de signes de régression. De plus, les adultes ont été trouvés avec beaucoup de réserves de graisses et la période de préoviposition pour 50 % des femelles transférées dans des conditions favorables a été de 90 jours au début de juillet et de 82 jours au début août. Pendant la période de quiescence hivernale, l’arrêt du développement ovarien a été caractérisé dans la plupart des échantillons, par l’immaturité des ovaires de toutes les femelles et dans quelques échantillons, par la présence de signes de régression chez quelques femelles. En hiver, les adultes ont été trouvés avec des réserves de graisses en quantités différentes et la période de préoviposition moyenne des femelles transférées dans des conditions favorables a été de 29 jours au début novembre et de 16 jours à la mi-janvier.

Temperature-Dependent Development, Survival, Longevity, and Fecundity of Propylea quatuordecimpunctata (Coleoptera: Coccinellidae)

ABSTRACT The effect of temperature on the development, survival, longevity, and fecundity of the 14-spotted ladybird beetle, Propylea quatuordecimpunctata L. (Coleoptera: Coccinellidae) reared on bean aphid, Aphis fabae Scopoli (Hemiptera: Aphididae) was determined at six constant temperatures (17, 20, 25, 30, 32.5, and 35 ± 1°C) in the laboratory. Results showed a temperature—dependent development of the coccinellid. An appropriate linear model indicated that 218.0 degree days above a threshold of 10.2°C were needed to complete immature development from egg to adult emergence. Data were fitted to the nonlinear Briere model, which for total immature period estimated the upper developmental threshold at 36.0°C, the lower threshold at 12.2°C and the temperature for maximum developmental rate at 30.3°C. Survival of immature stages varied significantly across temperatures with the lowest survival of just 14% occurring at 32.5°C and the highest (96%) at 25°C. In addition temperature showed a profound effect on female longevity over this viable range of temperatures, as it decreased from 123.06 d at 17°C to 33.53 d at 30°C. The highest fecundity (724.6 eggs/female) was recorded at 25°C. These results might be useful tools for the prediction of P. quatuordecimpunctata phenology and the interaction with its prey.

Temperature-Dependent Development of the Five Psyllophagous Ladybird Predators of Agonoscena pistaciae (Hemiptera: Psyllidae)

ABSTRACT The temperature-dependent development of five psyllophagous ladybirds, Adalia bipunctata (L.), Coccinella undecimpunctata aegyptica (Reiche), Exochomus nigripennis (Erichson), Hippodamia variegata (Goeze), and Oenopia conglobata contaminata (Menetries) (Coleoptera: Coccinellidae), was studied on the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psyllidae), in the laboratory. The lower developmental thresholds for total development (egg to adult) of the predators ranged from 10.9 (O. c. contaminata) to 14°C (C. u. aegyptica). The lowest and highest degree-day (DD) requirement values for total development of the studied cocinellids were estimated for C. u. aegyptica (166.67 DD) and E. nigripennis (344.83 DD), respectively. The optimum temperature for development of the studied ladybirds, calculated using third-order polynomial and Lactin models, was in the range of 27.5–30°C. This study showed that all the five psyllophagous ladybirds successfully complete their development in a wide range of temperatures from 17.5 to 30°C, indicating their high potential for use in biological control programs against A. pistaciae.

Effect of Temperature on the Development and Longevity of Planococcus ficus (Hemiptera: Pseudococcidae)

ABSTRACT The developmental biology of Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) on table grape (Vitis spp.) leaves (‘Soultanina’) was studied at seven constant temperatures—15, 17.5, 20, 25, 30, 32.5, and 35°C—under laboratory conditions. Developmental time and adult longevity were inversely related to temperature. No nymphs hatched from eggs when incubated at 15 and 35°C, whereas no nymphs survived at 32.5°C. The highest egg-to-adult survival (72.09%) was found at 30°C and the lowest (48.80%) at 25°C. The mean total developmental time from egg to adults for females ranged from 39.87 d at 30°C to 112.62 d at 17.5°C. The recorded sex ratio of the offspring was strongly female biased. Adult females lived from 27.64 d at 30°C to 63.70 d at 20°C, whereas males lived 1.66–7.55 d, respectively. Both linear and nonlinear models adequately described the relationship between temperature and developmental rates for immature stages of P. ficus. Thus, P. ficus required 555.56 degree-days to complete development from egg to adult stage, above a minimum threshold of 11.11°C as estimated by linear regression. The temperature thresholds for all nymph instars of P. ficus, estimated by the linear model, were lower than values that were estimated by the non linear model. The predicted upper lethal temperature was 32.5°C, with a minimum threshold for total development occurring at 14.20°C, as estimated by a nonlinear model. These results may lead to better management of P. ficus by improving predictions of its seasonal appearance.