Densities Of Different Stages Research Articles

Impact of Some Weather Factors on the Population Density of Phenacoccus solenopsis Tinsley and its Natural Enemies

The aimed of this investigation was to estimate the seasonal abundance and activity periods of the cotton mealybug, Phenacoccus solenopsis Tinsley and its associated parasitoid on okra plants. The present experiment was conducted at Hihhya distract, Sharkia Governorate during two consecutive seasons 2017 and 2018. Plant samples were taken weekly to calculate the population density of different stages of tested pest and its parasitoid, the effect of some weather factors, the number of generations and the best leaf surface. The present work was found a reverse relation between the populations of the cotton mealybug (CMB) and its associated parasitoids. The population dynamic of CMB was high while the population of its parasitoids was low in the first season. On the other hand, the opposite results were obtained during the second season. The P. solenopsis had two to three generations during the first and second seasons, respectively. There was significantly positive correlation between maximum temperature and the population females of this insect whereas, a significant negative correlation was found with mean of relative humidity during the period of this investigation.The results of this study may help the researchers for designing a comprehensive pest management program and prediction models for the cotton mealybug to restrict their further spread.

Population Density of the Red Spider Mite Tetranychus urticae Koch (Acari:Tetranychidae) on Some Vegetable Crops at Fayoum Governorate

Population density of different stages of Tetranychus urticae Koch. was conducted on two host plants; cucumber and eggplant during the two successive seasons 2015 and 2016 from March to August. Data indicated that T. urticae stages disappear in samples of March and reached to the highest peak on July during the two seasons on cucumber and eggplant. The correlation was significant positive between different stages of T. urticae and temperature during the two seasons for two the plant crops.

BIOLOGICAL, ECOLOGICAL, AND BIO-CONTROL STUDIES ON SOME INSECTS ATTACKING TOMATO PLANTS.

This work was conducted in some pests attacking tomato plants. The main purpose of this work was to throw the light on survey of the different pests infesting tomato plants at three Egyptian governorates, the population density of different stages of Tuta absoluta (Lepidoptera: Gellchiidae), effect of pheromone trap number on trapped T. absoluta, study on the feeding habits of the predator Nesidioeoris tennis (Hemiptera: Miridae) and IPM program to Tuta absoluta. The main results of study could be summarized as follow: The result obtained as shown that there are ten species were recorded during this study, those belonging to eight orders, Orthoptera, Hemiptera, Thysanoptera, Neuroptera, Lepidoptera, Coleoptera, Diptera and Hymenanptera. Five predators and one parasitoid associated with the insect pests on tomato plants in different Governorates of study. The population density of T. absoluta eggs, larvae, captured male moths and the damage caused by larvae (mines) occurring on tomato plant was significantly higher in summer season 2014 than in the winter season 2013. The number of traps with recommended rate attracted higher number and failed in traps, whereas in the other one attracted higher numbers but not fail as whale in traps. Predator Nasidocoris tenuis Reuter (Hemiptera: Miridae) attack the insect pest Tuta absoluta (Lepidoptera: Gellchiidae) but started to feed on the host plants when the prey numbers decreased or not available. IPM applications used for T. absoluta control was more effective than used in the control field applications during summer season 2014.

Fluctuations in Natural Populations of the Leaf miner (<i>Coelaenomenodera lameensis</i>) in Relation to Different Origins of Oil Palm (<i>Elaeis</i> sp.) in South Benin

Preferences of different oil palm crosses in the station of Pobè in Benin were tested on Coelaenomenodera lameensis by monitoring the natural population for 7 consecutive years. Experiments monitoring of developmental stages of the insect were performed on material types Elaeis guineensis and Elaeis oleifera. Observations were performed every two weeks on leaves of different ranks (25, 17 or 9) depending on the degree of defoliation by counting the different stages of insect development on leaflets. The results showed that the evolution of pest density is a function of species and the origin of the materials being compared. Population densities of different stages of C. lameensis were more abundant in the crosses from Yocoboué where average population indices were higher at all stages of development from early observations. By contrast, in crosses La Mé, Yangambi and Deli, the numbers of larvae, pupae and adults were lower. Among these three crosses infestation was more abundant in La Mé, followed by Yangambi and Deli. E. oleifera is much less or not attacked. The stages of development (larvae and adults) were also differently held in oil palm origins in comparison. The larval population is significantly important during the short rainy season and lesser important during the dry season. These results may contribute to the development of suitable materials for the genetic improvement of breeding tolerant oil palm material to leaf miner.

Prey-stage preference and population increase of the predaceous mite Kampimodromus aberrans (Oudemans) (Acari: Phytoseiidae) on Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions

ABSTRACT The developmental time, survival, and fecundity of Kampimodromus aberrans (Oudemans) (Acari: Phytoseiidae) when feeding on Tetranychus urticae Koch (Acari: Tetranychidae) plus birch pollen were investigated at 16, 20, 25 and 30 ± 1°C, 65 ± 10% relative humidity, and 16:8 light:dark photoperiod in the laboratory. Also, the prey-stage preference of adult female K. aberrans was assessed at constant densities of different stages of T. urticae and T. urticae plus birch pollen. Experiments were carried out using bean leaf discs as substrate. Total developmental times of K. aberrans were 37.1, 26.6, 8.0, and 7.4 days for females and 32.1, 24.6, 7.4, and 7.3 days for males at 16, 20, 25, and 30 ± 1°C, respectively. The total egg production was highest (17.2 eggs) at 25°C, while the daily egg production was at its highest (1.1 eggs) at 30°C. The female longevity of K. aberrans was determined as 75.6, 58.8, 25.8, and 17.4 days at 16, 20, 25, and 30 ± 1°C, respectively. The development threshold of the eggs and pre-adult stages were 13.75 and 13.55°C for females, and 13.58 and 12.92°C for males, respectively. Total effective temperature was 33.78 and 112.35 degree-days for females and 33.44 and 113.63 for males. The mite had the highest intrinsic rate of increase, (r m ) 0.129 ♀/♀/day at 30°C, followed by 0.108 ♀/♀/day at 25°C and 0.034 ♀/♀/day at 20°C, while at 16°C, K. aberrans displayed the lowest r m value (0.023 ♀/♀/day). In the prey-stage preference experiments, the adult female K. aberrans consumed significantly more prey larvae of T. urticae alone, but, when the predatory mite was offered T. urticae plus birch pollen, they consumed significantly more eggs.

Consumption rate and functional response of the predaceous mite Kampimodromus aberrans to two-spotted spider mite Tetranychus urticae in the laboratory

Prey stage preference of female Kampimodromus aberrans (Oudemans) (Phytoseiidae) at constant densities of different stages of Tetranychus urticae Koch (Tetranychidae), functional response types and parameters of the predator females to the varying densities of eggs, larvae, protonymphs and deutonymps of T. urticae were determined in order to establish its potential for the mite biological control. Experiments were conducted at 25 ± 1 °C, 65 ± 10% RH and 16:8 (L:D) photoperiod. Our results indicated that the predator consumed significantly more prey larvae than other prey stages. Functional response type of predator was determined by a logistic regression model. The predator exhibited a Type II response on all prey stages. The attack rate (α) and handling time (T ( h )) coefficients of a Type II response were estimated by fitting a "random-predator" equation to the data. The lowest estimated value α and the highest value of T ( h ) (including digestion) were obtanined for the predator feeding on deutonmph. The lowest value of T ( h ) were obtained for the predator feeding on prey larvae, but the attack rate value obtained on larva wasn't different than that obtained on egg and protonymph. According to our results, K. aberrans could be an efficient biological control agent of T. urticae at least at low prey densities. However, further field based studies are needed to draw firm conclusions.

Prey stage preference and functional response of Euseius hibisci to Tetranychus urticae (Acari: Phytoseiidae, Tetranychidae)

The aims of this study were: (a) determine the prey stage preference of female Euseius hibisci (Chant) (Phytoseiidae) at constant densities of different stages of Tetranychus urticae Koch (Tetranychidae), (b) assess the functional response of the predator females to the varying densities of eggs, larvae, or protonymphs of T. urticae, and (c) estimate the functional response of E. hibisci when pollen of Ligustrum ovalifolium was present as well. We conducted experiments on excised pieces of strawberry leaf arenas (Fragaria ananassa) under laboratory conditions of 25+/-2 degrees C, 60+/-5% RH and 12 h photophase. Our results indicated that the predator consumed significantly more prey eggs than other prey stages. Consumption of prey deutonymphs and adults was so low that they were excluded from the non-choice functional response experiments. The functional response on all food items was of type II. The two parameters of the functional response were estimated for each prey type by means of the adjusted non-linear regression model. The highest estimated value a' (instantaneous rate of discovery) and the lowest value of Th (handling time, including digestion) were found for the predator feeding on prey eggs, and a' was lowest and Th highest when fed protonymphs. Using the jack-knife method, the values for the functional response parameters were estimated. The values of a' and Th produced by the model were similar among all prey types except for the eggs, which were different. Using pollen simultaneously with prey larvae decreased the consumption of the latter over the full range of prey densities The suitability of this predator for biological control of T. urticae on strawberry is discussed.

PREDATION OF THE LADYBEETLE CHILOCORUS KUWANAE ON THE SCALE UNASPIS YANONENSIS

Abstract The prey consumption of ovipositing female adults of the ladybeetle Chilocorus kuwanae on the scale Unaspis yanonensis was found to be significantly greater than that of the male adults. At 25°C one female adult ladybeetle, on average, would consume 42. 7 female scale adult per day while one male adult only destroyed 22. 3 female scale adults. However, after a deprivation of the prey for 48 h, this difference was eliminated. A C. kuwanae female adult had to prey on at least 15 U. vanonensis female adults in order to lay eggs. The funcional responses of the beetle adults to densities of different stages of the scale followed Holling's type 1. The functional responses to female scale adults indicated that the maximum prey consumption went up with the increase in temperature from 16°C to 35°C, and dropped sharply at 37°C. However, temperature did not alter the type of the functional response. Rased on the predation of C. kuwanae adults on U. yanonensis female adults, the minimum critical, optimal and maximum critical temperatures for their attack were estimated to be 10. 6°C, 31. 5°C and 38. 2°C respectively. The increase in predation space or in predator density could result in a reduction in the attack rat‐e, but with the increase of predator density, the effect of predation space became much smaller. C. kuwanae adults preferred male pupae to other stages of the scale, and their preference for various stages of the prey was in the order of male pupae, 2nd‐instar male nymphs, 2nd‐instar female nymphs, adult females and kinstar nymphs.

A comparative account of coelomocytes and haemocytes of five species of earthworms

Coelomocytes and haemocytes of 5 local species of earthworms were studied. The structure of different cells is the same in different species. The total and differential account of the haemocytes showed some species specificity.Perionyx excavatus, a species that can be adapted to a wide range of temperature, on acclimation to 8° C cold, did not show any significant change in the total count of cells, but did show some changes in the density of different stages of eleocytes.

The Spatial Distribution of Two Pine Sawflies and Methods of Sampling for the Study of Population Dynamics

AbstractThe spatial distribution of egg clusters and cocoons of Neodiprion swainei and N. sertifer is described, and methods are developed for estimating the density of different stages on the same numerical basis.Egg-cluster density varies directly with height in the tree, branch length, and tree size, evidently due to the females’ preference for illuminated sites. The overdispersion of egg-cluster counts reflects the heterogeneity of distribution of suitable oviposition sites rather than an inherent aggregative behaviour of parent females. Cocoon density within stands is not strongly related to the distance from the nearest tree, due to the wide dispersal of cocoon-spinning larvae. Some of the overdispersion of cocoon counts is due to differences in cocoon density between sections of a stand. Cocoons of males are more highly aggregated than those of females, and cocoons attacked by predators are more highly aggregated than ones not attacked.The sampling unit selected for each life-history stage is one that permits density estimates of desired precision at minimum cost. In some stands, egg density can be estimated at minimum cost by direct counts per quadrat, in most stands, however, the whole tree is the most economical unit, despite the fact that per-tree density must be converted to absolute density in order to express all stages on a common basis. Sampling error can be reduced by stratification according to tree size. Gradients in cocoon density are seldom steep enough to permit stratification, but the cost of sampling can be minimized by adjusting unit size. Optimal unit size varies inversely with cocoon density and degree of aggregation, and is affected by soil type and the method used to extract cocoons.The role of spatial distribution and sampling programs in studies of population dynamics is discussed.