Tetranychus urticae Koch is a cosmopolitan pest whose rapid developmental rate enables it to produce colonies of thousands of individuals within a short time period. When a solitary virgin female colonizes a new host plant, it is capable of producing male offspring through the arrhenotokous parthenogenesis; once her sons mature, oedipal mating occurs and the female will produce bisexual offspring. To analyze the effect of arrhenotokous reproduction on population growth, we devised and compared separate life tables for arrhenotokous and bisexual populations of T. urticae using the age-stage, two-sex life table theory. For the cohort with bisexual reproduction, the intrinsic rate of increase (r), finite rate (λ), net reproductive rate (R0), and mean generation time (T) were 0.2736 d(−1), 1.3146 d(−1), 44.66 offspring, and 13.89 d, respectively. Because only male eggs were produced during the first 8 d of the oviposition period and the cohort would soon begin bisexual reproduction, it would be theoretically wrong to calculate the population parameters using the survival rate and fecundity of an arrhenotokous cohort. We demonstrated that the effect of arrhenotokous reproduction could be accurately described and evaluated using the age-stage, two-sex life table. We also used population projection based on life table data, quantitatively showing the effect that arrhenotokous reproduction has on the growth potential and management of T. urticae.

Survival and Reproductive Strategies in Two-Spotted Spider Mites: Demographic Analysis of Arrhenotokous Parthenogenesis of Tetranychus urticae (Acari: Tetranychidae)

https://ainfo.cnptia.embrapa.br/digital/bitstream/item/116511/1/Eudes-cpatsa.pdf

Monitoring Tetranychus urticae Koch (Acari: Tetranychidae) resistance to abamectin in vineyards in the Lower Middle São Francisco Valley

The biology of two-spotted spider mite, Tetranychus urticae Koch and seasonal incidence of mites infesting citrus was studied during 2013-2014 at the Acarology Laboratory, Entomological Research Farm, Department of Entomology and New Orchard, Department of Fruit Science, Punjab Agricultural University, Ludhiana. Biological studies on T. urticae revealed that the mean incubation, larval, protonymphal and deutonymphal period was found to be 2.52, 2.74, 2.08, and 2.40 days, respectively. The pre-oviposition, oviposition and post-ovipostion period was 0.96, 1.78 and 6.40 days, respectively. The fecundity of 1.56 eggs/female and longevity of females (9.40 days) and males (6.71 days) was observed. The sex ratio was in favour of females (4.33:1). Studies on oviposition response of T. urticae on different citrus genotypes revealed that oviposition was found to be maximum on SL-4 and G-4 followed by BL-2 and G-4 genotypes and no egg laying was observed on SL-3, SL-7, G7, BL-1, BL-3 and Tahiti lime. Feeding preference studies revealed that mites preferred KL-7 genotype the most, but had least preference for G-4 genotype. Observations on the seasonal incidence revealed that peak occurrence of Brevipalpus phoenicis was reported during 47 th standard week (SW) (23.0 mites/leaf); Tetranychus urticae during 21 st SW (6.25 mites/leaf), while Polyphagotarsonemus latus started occurring during November-December (47 th to 25 th SW). The population of Eutetranychus orientalis was observed during April-June (16 th to 26 th SW) as with increase in temperature there was increase in population of mites. The population of predatory mites viz. Tydeids, Phytoseiids and Cunaxids was observed throughout the year with peak incidence during 29 th SW and 46 th SW, respectively. Although the mite populations showed both negative and positive correlations with the various abiotic parameters, but statistically these were found to be non significant.

Biology of tetranychus urticae koch and seasonal incidence of mites infesting citrus

Seasonal abundance of the two spotted spider mite, Tetranychus urticae (Koch) (Acari) infesting cucumber plants in Upper Egypt was studied during three seasons of 2014, 2015 and 2016 in Assiut Governorate. The obtained results showed that the spider mite, T. urtica population during spring plantations fluctuated in relatively high densities during whole season with a peak during the middle of May when the plant age was 43 day-old and the presence of an average level of temperature and relative humidity. In addition, the data indicated that the number of predators was not significantly correlated with pest populations during the spring plantations of 2015 and 2016 seasons, probably because of the lowest numbers of predators recorded in the studied area. The present study showed that the cucumber plants severely affected by the two spotted spider mite, T. urticae. In addition to the scarce numbers of predators recorded during spring and/or summer plantations.

Activity of the two spotted spider mite, Tetranychus urticae (Koch) (Acari) infesting cucumber plants in upper Egypt

........................................................................................................... V TABLE OF CONTENTS ........................................................................................ VII LIST OF FIGURES .............................................................................................XIV LIST OF TABLES ...............................................................................................XIX CHAPTER 1 ............................................................................................................ 1 GENERAL INTRODUCTION .................................................................................... 1 1.

Sex-specific aging in two-spotted spider mite Tetranychus urticae: Effects of diet, social environment and predator-induced stress

Developmental times and reproduction rates of the two-spotted spider mite Tetranychus urticae Koch were studied when fed on leaves of two pear varieties (i.e. Lacont and Hood varieties) under laboratory conditions of 15, 20, 25 & 30 ± 2°C, 70% ± 5% RH. The longest developmental stages reached 30.6 and 30.1 days for female and male at 15°C when the T. urticae was fed on Lacont pear variety, while when reared on Hood pear variety it was 34 and 32.1 days at the same temperature. The highest total mean fecundity rate was recorded at 30oC (156.8 and 143.6 eggs /female). Sex ratio was affected by temperature as proportion of female increased. In addition, the values of rm and λ increased with temperature increase, while mean generation time (T) and generation doubling time (DT) values decreased with temperature increase, thus the reproduction of mites increased. This mite favored high temperature. The Lacont pear variety was more favored to this mite.

https://eajbsz.journals.ekb.eg/article_13876_9d809f01968f351409f1b8265cb557f6.pdf

Nazeh M. Abd El-Wahed

Papers

Effect of Temperature Degrees on the Biology and Life Table Parameters of Tetranychus urticae Koch on Two Pear varieties