Diet-dependent life history,feeding preference and thermal requirements of the predatory mite <Emphasis Type="Italic">Neoseiulus baraki</Emphasis> (Acari: Phytoseiidae)

Neoseiulus baraki Athias-Henriot (Acari: Phytoseiidae) has been reported from the Americas, Africa and Asia, often in association with Aceria guerreronis Keifer (Acari: Eriophyidae), one of the most important pests of coconut (Cocos nucifera L.) in different parts of the world. That phytoseiid has been considered one of the most common predators associated with A. guerreronis in Brazil. The objective of this study was to evaluate the feeding preference and the effect of food items commonly present on coconut fruits and several temperature regimes on the life history of a Brazilian population of N. baraki. Completion of immature development was possible when N. baraki was fed A. guerreronis, Steneotarsonemus concavuscutum Lofego and Gondim Jr., and Tyrophagus putrescentiae (Schrank). Fecundity was highest on T. putrescentiae (39.4 eggs), followed by A. guerreronis (24.8 eggs). In choice tests, irrespective of the food on which N. baraki was reared, a larger number of adults of this predator chose leaf discs containing A. guerreronis than discs containing other food items, demonstrating a preference of the former for the latter as food. Egg to adult thermal developmental time was calculated as 84.2 degree-days, above a threshold of 15.8°C. This lower developmental threshold is higher than previously published for phytoseiid species from higher latitudes. Neoseiulus baraki was shown to have higher biotic potential at 30°C (r _m 0.29). The results suggest N. baraki to be a promising biological control agent of A. guerreronis, well adapted to survive and develop in areas with relatively high temperatures, where that pest prevails.     

Population dynamics of <Emphasis Type="Italic">Aceria guerreronis</Emphasis> (Acari: Eriophyidae) and its predatory mite, <Emphasis Type="Italic">Neoseiulus baraki</Emphasis> (Acari: Phytoseiidae) in two coconut growing areas in Sri Lanka

Densities of coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae) and its predatory mite, Neoseiulus baraki Athias-Henriot (Acari: Phytoseiidae) were monitored on coconut fruits in two coconut mite infested areas, Kalpitiya and Madurankuliya, in Sri Lanka, over a period of 3 years and were compared with local rainfall records. Significant differences in A. guerreronis densities were observed among years and months of the year. Rainfall (amount and frequency, i.e. the total number of days with rainfall of >5 mm) was not significantly correlated with the variation of A. guerreronis densities. But the drought length (i.e. the number of days without rainfall of >5 mm) significantly influenced A. guerreronis densities. Generally, peak densities of A. guerreronis were observed during February–March and June–September in both areas. The differences in the N. baraki densities were significantly different between the two areas and among the 3 years but not among months of the year. Although the amount of rainfall was not significantly correlated with the population densities of N. baraki, frequency of rainfall showed a negative significant correlation and drought length showed a positive significant correlation with the population densities. The results of this experiment indicated that the application of control methods for A. guerreronis may be more advantageous if they are carried out at the onset and during the dry seasons.     

Life History of Kampimodromus aberrans as a predator of Phytoptus avellanae (Acari: Phytoseiidae, Phytoptidae)

The biology of Kampimodromus aberrans (Oudemans), a predator of the big bud mite, Phytoptus avellanae Nalepa, was studied under laboratory conditions. All experiments were conducted on hazelnut leaf discs in an incubator at 25 ± 1 °C, with 16:8 h L:D, at an average daily relative air humidity of 76%. Observations were made twice daily for the immature stages and daily for the adults to determine developmental time, survival and fecundity. The mean developmental time for females was 6.90 days and for males was 7.10 days, and mean adult longevity for females was 11.67 days. The mean total and daily egg production were 12.67 and 1.85 eggs, respectively. The net reproduction rate (R₀) was 7.09 females/female, intrinsic rate of increase (r_m) was 0.153 female/female/day and mean generation time (T₀) was 12.80 days. The mortality rate of immature stages was 0.66% and the sex ratio was 0.51 female.     

Influence of diet on biology and life-table parameters of the predacious mite Euseius scutalis (A.H.) (Acari: Phytoseiidae)

Abstract

Studies on the developmental duration, immature survival, longevity, reproduction, and life-table parameters of the predatory mite, Euseius scutalis Athias-Henriot were carried out under laboratory conditions of 28 ± 1°C and 75 ± 5% relative humidity (RH). The food sources for the predator included Ricinus communis pollen, eggs and nymphs of Eutetranychus orientalis, moving stages of Aceria ficus and Rhyncaphytoptus ficifoliae and immature stages of Icerya aegyptica. Development was faster and reproduction was higher when E. scutalis fed on R. communis pollen, while the developmental time increased and reproduction decreased when fed on R. ficifoliae. The number of A. ficus consumed was significantly higher compared with R. ficifoliae. Life-table parameters showed that a diet of R. communis pollen provided the shortest generation time (T = 9.51511 days), female longevity (21.37 days), the highest intrinsic rate of natural increase (rm = 0.33789) and greatest total fecundity, which resulted in the high net reproductive rate (Ro = 24.906) value. Aceria ficus and R. ficifoliae showed a relatively close value of (T = 11.59057 and 11.5222), (rm = 0.218029 and 0.2158297), (λ = 1.243623 and 1.240891) and the number of eggs deposited per female per day (1.20 and 1.20 eggs/♀/day). Eggs of E. orientalis were the least favourable source of food among all food tested.     

The effects of prestarvation diet on starvation tolerance of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae)

Understanding the factors affecting stress tolerance in phytoseiid mites is critical for their integration into biological control programs. In the present study, the effects of diet (varying in prey species, physiological status and phenotype) are examined on the future starvation tolerance of the predatory mite Neoseiulus californicus McGregor (Acari: Phytoseiidae). The predators are fed from egg to adulthood on diapausing or nondiapausing Tetranychus urticae, Tetranychus kanzawai (wild and albino strains) or the nondiapausing species Panonychus citri (wild and albino strains). Thereafter, 3‐day‐old mated adult females are held without food at 25 ± 1 °C and a relative humidity of 98 ± 2%. The survival of these starved females is observed daily until all females have died. The survival curves and mean survival times of N. californicus are found to vary among prey types and are significantly longer when the predator is fed with diapausing prey. This enhanced survival is consistent with high concentrations of glycogen and triacylglyceride in the body of the predator at the onset of starvation. The predators fed nondiapausing prey have shorter survival times, and the glycogen and triacylglyceride contents in their bodies are low or undetectable. The protein contents of the predator's body are similar after consuming different prey types, except for a high concentration when fed the albino strain of P. citri. Protein content is unlikely to play a direct role in starvation tolerance, although it may affect the response to varying glycogen and triacylglyceride levels. These findings indicate that nutritional value of prey has a strong impact on the starvation tolerance of N. californicus.     

Comparative life table analysis of Tetranychus urticae (Acari: Tetranychidae) on 14 soybean genotypes

Abstract The life table parameters of two‐spotted spider mite (TSSM), Tetranychus urticae Koch, on 14 soybean genotypes (Sari, Sahar, Tellar, Zane, Ks3494, L₁₇, Dpx, 032, 033, Clark, Hill, I27, Tms and Williams) were evaluated at 28 ± 1°C, 65%± 5% RH and a photoperiod of 16 : 8 h L : D. The survivorship data (l_x) of adult females were fitted to the Weibull frequency distribution model in all genotypes tested. Based on the Weibull parameters, the survival curve was type I on all genotypes, which indicated that the mortality mostly occurred in old individuals. Furthermore, two mathematical models (Analytis and Enkegaard) were fitted to age‐specific fecundity data (m_x). The highest intrinsic rate of increase (r_m) was recorded on L₁₇ (0.392) and the lowest values of this parameter were obtained on Tms (0.233), Hill (0.236), 032 (0.236), I27 (0.237) and Clark (0.240). In addition, net reproductive rate (R₀) and finite rate of increase (λ) of the TSSM had the highest value on L₁₇ as 45.521 and 1.475, respectively. The lowest values of these parameters were recorded on Tms as 12.149 and 1.258, respectively. Doubling time (DT) varied significantly on different genotypes and the shortest and longest values of this period were obtained on L₁₇ and 032, respectively. Our findings revealed that Tms, Hill, 032, I27 and Clark were less suitable genotypes, suggesting that they are more resistant to the TSSM than the other genotypes.     

Reproductive parameters and life expectancy of Tetranychus urticae (Acari: Tetranychidae) on 12 genotypes of melon and cucumber in laboratory condition

The effect of two host plant species including eight genotypes of melon (Cucumis melo L.) and four genotypes of cucumber (Cucumis sativus L.) was studied on reproductive parameters: life expectancy and mortality of Tetranychus urticae (Koch) at 25?±?1?°C, 60?±?5% rh and a photoperiod of 16L:8D hours. The results indicated that the highest value of the gross fecundity rate of T. urticae was 96.72?±?16.70 (eggs/female) on Mir sultan and the lowest value was 14.33?±?0.88 on Ananasi. The maximum value of gross fertility rate (41.55?±?4.79) was recorded on Sultan, while the minimum value (1.38?±?0.08) was recorded on Ananasi. The net fecundity rate was varied from 0.47?±?0.09 on Ananasi to 23.53?±?3.96 eggs/female on Sultan. The net fertility rate was 12.96?±?2.18 on Sultan and 0.04?±?0.009 on Ananasi, which was the maximum and minimum values, respectively. The range of gross hatch rate on different melon and cucumber genotypes was 9.67% on Ananasi to 72.46% on Super sultan. The cohort reared on Super sultan had the highest mean eggs per day and those on Shah abadi had the lowest mean eggs per day. In addition, the mite demonstrated the maximum value of mean fertile eggs per day with the amount of 1.66?±?0.19 eggs/female when fed on Sultan, and Ananasi demonstrated the minimum value (0.09?±?0.005). The life expectancy of one-day-old adults of T. urticae was estimated to be 16?days on Garmak Isfahan and 26.62 days on Mir sultan which is the maximum and minimum values, respectively. Furthermore, the highest mortality percentage of immature stages of T. urticae was recorded on Ananasi and the lowest was recorded on Super sultan. Comparison of the data collected in this study revealed that the mites had considerably better performance on cucumber genotypes than melon genotypes, so we can assume that cucumber is the preferable host species for T. urticae. The use of preferable and resistant host plants is helpful in crop rotation and it will be one of the beneficial strategies to integrated pest management programmes.     

Prey preference of predatory mite Amblyseius swirskii (Acari: Phytoseiidae) on Tetranychus urticae (Acari: Tetranychidae) and Bemisia tabaci (Hemiptera: Aleyrodidae)

Tetranychus urticae Koch (Acari: Tetranychidae) and Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) are major pests in greenhouse crops. Recently, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was shown to be an effective biological control agent of both pests. Therefore, the prey preference of A. swirskii was determined using immature stages of T. urticae and B. tabaci in three various treatments based on Manly's β preference index (β). These treatments consisted of immature stages of two prey species (egg, first and second instar nymphs) with densities 12:12, 6:6 and 3:3, respectively, and with 13 replicates. After 24?h starvation, same-aged females of A. swirskii were added to the leaf discs. All experiments were done on bean leaf discs in Petri dishes (8?cm in diameter) in laboratory conditions with 25?±?2°C, 70?±?5% relative humidity and the photoperiod of 16L:8D hours. Comparing the preference indices using t-tests indicates a significant preference of the predator on eggs (t?=?10.80, df?=?24, P?t?=?8.17, df?=?24, P?T. urticae than B. tabaci. Our findings suggest that developmental stages of prey have effect on the prey selection by A. swirskii.     

Biological studies of the predacious mite Amblyseius swirskii,a predator of the broad mite Polyphagotarsonemus latus on pepper plants (Acari: Phytoseiidae: Tarsonemidae)

The predatory phytoseiid mite Amblyseius swirskii (Athias-Henriot) completed its lifespan when fed on females of the broad mite, Polyphagotarsonemus latus (Banks). The development was the quickest and the number of prey consumed was highest when individuals were reared at 28?°C compared with 19?°C. The average number of eggs/female/day was 2.36 and 1.69, respectively. Life table parameters showed that the population of A. swirskii multiplied 16 and 20 times in a generation time of 22 and 18?days at 19 and 28?°C, respectively. Under these conditions, the intrinsic rate of increase (rm) was 0.139 and 0.170 individuals/female/day, respectively.     

The biology of the predatory miteHypoaspis miles (Acari: Laelapidae), a potential biological control agent ofBradysia paupera (Dipt.: Sciaridae)

The following aspects ofHypoaspis miles' biology were investigated; development rate of egg to adult at different temperatures, fecundity, longevity and rate of predation on sciarids. With an increase in temperature the time taken for development decreased from 33.7 days at 15°C to 9.2 days at 28°C. The threshold temperature forH. miles to complete its life cycle was between 10° and 12°C. When fed onAcarus siro, H. miles laid 2–3 eggs a day and unfertilized eggs only developed into males. Adults ofH. miles (0–1 day old) survived for 24.0±1.4 days without food and if fed for 6 days and then starved, females lived for 65.4±2.6 days which was significantly longer than males (45.2±3.0 days). With food, 60% of males and females survived for 142 days. All larval instars of sciarids were attacked byH. miles although the numbers consumed were dependent on the size of the larvae. Egg predation was negligible and pupae were not attacked. In productivity studies ofH. miles in culture (fed onA. siro), the time taken for the mites to reach a density of 45–65,000/litre ranged from 76 to 23 days at 15° and 28°C respectively.

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Résumé Différents aspects de la biologied'Hypoaspis miles sont examinés: vitesse de développement de l'oeuf à l'adulte à différentes températures, fécondité, longévité et voracité sur les sciarides. Avec une augmentation de la température, la durée du développement passe de 33,7 jours à 15°C à 9,2 jours à 28°C. La température minimale qui permet le développement complet deH. miles est située entre 10 et 12°C. Quand il est nourri d'"itAcarus siro, H. miles pond 2 à 3 oeufs par jour et seuls les oeufs non fécondés donnent des males. Les adultes deH. miles (agés de 0 à 1 jour) survivent pendant 24±1,4 jours sans nourriture et si elles sont nourries pendant 6 jours puis privées de nourriture, les femelles vivent 65,4±2,6 jours, ce qui est significativement plus long que les males (45,2±3 jours). Avec de la nourriture, 60% des males et des femelles vivent pendant 142 jours. Toutes les larves de sciarides sont attaquées parH. miles, mais le nombre de proies consommées dépend de la taille des larves. La prédation des oeufs est négligeable et les pupes ne sont pas attaquées. Dans des études sur la productivité deH. miles en élevage (nourri deA. siro), la durée nécessaire aux acariens pour atteindre une densité de 45–65 000/1 est de 76 et 23 jours à 15°C et 28°C respectivement.

     

Isolation of Psoroptes scab mite microsatellite markers (Acari: Psoroptidae)

Nine microsatellite markers have been isolated from the scab mite, Psoroptes ovis. These markers have been tested for polymorphism in individual Psoroptes mites originating from two hosts, the European rabbit, Oryctolagus cuniculus, and sheep, Ovis aries. No definitive picture of Psoroptes species’ status or interrelationships exists. This study provides the basis for a new molecular system to elucidate the systematics of groupings within the genus Psoroptes, allowing us to clarify the population dynamics and epidemiology of the mites causing sheep scab world wide.     

Two new myrmecophilous species of the genus Scutacarus (Acari: Prostigmata: Scutacaridae) with world keys to related species groups

In a survey on heterostigmatic mites (Acari: Prostigmata: Heterostigmata) associated with insects including ants in northwestern Iran, two new species of myrmecophilous mites of the genus Scutacarus (Acari: Scutacaridae) were found. They are S. shajariani sp. nov. phoretic on Tetramorium sp. (Hymenoptera: Formicidae) and S. ebermanni sp. nov. phoretic on Messor sp. The mentioned new species belong to groups of species with reduced setae e and h₂, and no setae 4b, respectively. These two new species are described and illustrated, and world keys are provided for respective species groups.     

Three new species of the genus Caesarodispus (Acari: Microdispidae) associated with ants (Hymenoptera: Formicidae), with a key to species

Three new species of the genus Caesarodispus (Acari: Heterostigmatina: Microdispidae) phoretic on ants are described from Iran: C. khaustovi Rahiminejad & Hajiqanbar sp. nov. , C. pheidolei Rahiminejad & Hajiqanbar sp. nov. and C. nodijensis Rahiminejad & Hajiqanbar sp. nov. All species were associated with alate ants of the subfamily Myrmicinae (Hymenoptera: Formicidae) from northern Iran. A key to all species of Caesarodispus is provided.     

Distribution of <Emphasis Type="Italic">Aceria guerreronis</Emphasis> and <Emphasis Type="Italic">Neoseiulus baraki</Emphasis> among and within coconut bunches in northeast Brazil

Aceria guerreronis Keifer (Acari: Eriophyidae) is considered a major pest of coconut in many countries in the Americas, Africa and parts of Asia. Neoseiulus baraki Athias-Henriot (Acari: Phytoseiidae) is one of the predatory mites most commonly found in association with A. guerreronis in parts of northeast Brazil. The objective of this work was to study the distribution of A. guerreronis and N. baraki among and within coconut bunches. The hypothesis was tested that A. guerreronis and N. baraki are homogenously distributed over the fruits in a bunch, independent of the fruits’ age and position. Five collections of bunches, each corresponding to leaves 12–16 from apex (about 2–6 month-old), were conducted in each of three fields in northeastern Brazil, from February to October, 2007. A total of 1,986 fruits were examined. The number of mites, the percentage of fruits hosting them and the level of damage caused by A. guerreronis were evaluated. The highest density of A. guerreronis was observed on fruits of bunch 4 whereas the highest density of N. baraki was observed on bunch 5. Considering all fruits together, no significant differences were observed between densities of either A. guerreronis or N. baraki among the basal, median and apical thirds of the bunches. In younger bunches, fruits of the apical region tend to have lower densities of both mites than fruits of the basal region. This pattern, in association with a similar pattern for the percentage of fruits hosting N. baraki, suggests that the predator initially reaches the basal bunch region, from where it moves to the apical region. The results of the present study suggest that the pest population reduction in bunches older than bunch 4 could be due to (1) an effect of the predator, (2) reduction of the proportion of undamaged tissues amenable to attack, and/or (3) less favorable characteristics of the fruits to attack by A. guerreronis, as indicated by their increasing lignin content as they get older.     

Temperature-dependent development and oviposition models and life history characteristics of Amblyseius eharai (Amitai et Swirski) (Acari: Phytoseiidae) preying on Tetranychus urticae (Koch) (Acari: Tetranychidae)

Amblyseius eharai, a native predatory mite in Korea, has a potential as a biological control agent for small-sized pests. However, its ecological characteristics remain unclear. Thus, the objective of this study was to construct temperature-dependent development and oviposition models of A. eharai and evaluate its life table parameters. Its development was examined at 11 temperatures (18.0, 20.1, 21.6, 24.0, 24.1, 27.4, 28.6, 30.2, 32.0, 33.2, and 35.9 °C). The life table analysis was conducted using experimental data from 6 temperatures (18.0, 21.6, 24.1, 27.4, 30.2, and 33.2 °C). Development and fecundity of A. ehari were well described by the Briere 1 model and an extreme value function, respectively. The intrinsic rate of increase (r) was the highest (0.2619) at 27.4 °C and the lowest (0.0792) at 18.0 °C. Based on r values of A. eharai obtained in this study and published information of Calepitrimerus vitis, A. ehari has higher r values than C. vitis. A. eharai appears to have good potential as a biological control agent against C. vitis in vineyards.     

An alien Sennertia mite (Acari: Chaetodactylidae) associated with an introduced Oriental bamboo‐nesting large carpenter bee (Hymenoptera: Apidae: Xylocopa) invading the central Honshu Island,Japan

Since 2006, an introduced Oriental bamboo‐nesting large carpenter bee, Xylocopa tranquebarorum, has been recorded from the central Honshu Island, Japan, which is inhabited only by the endemic subspecies, Xylocopa appendiculata circumvolans. Carpenter bees (tribes Xylocopini and Ceratinini) have ecological associations with specific Sennertia spp. in all geographic regions of their distribution, thus it is worried that the introduced carpenter bee has brought non‐indigenous mites into Japan. In their native ranges, X. a. circumvolans and X. tranquebarorum each has specific Sennertia mite faunas: the four Japanese Alloxylocopa bees including X. a. circumvolans have associations with S. alfkeni, while X. tranquebarorum has association with S. potanini in China (except Taiwan) and with S. horrida in South to East Asia including Taiwan. In the present study, we examined phoretic mite fauna on the introduced X. tranquebarorum, and determined whether the mites are indigenous or not based on morphological character and two gene sequences (mitochondrial cytochrome oxidase subunit I gene and nuclear ribosomal internal transcribed spacer). It was found from the result of this study that the non‐indigenous Sennertia mite has invaded Japan with the introduced X. tranquebarorum. We discuss geographic origin of the introduced X. tranquebarorum based on associated mite fauna and potential ecological risk caused by the introduced Xylocopa‐Sennertia association.     

Rearing of coconut mite Aceria guerreronis and the predatory mite Neoseiulus baraki in the laboratory

A method was developed for the rearing of coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), and its predatory mite Neoseiulus baraki (Athias-Henriot) (Acari: Phytoseiidae) on embryo culture seedlings of coconut (Cocos nucifera) in the laboratory. Seedlings in the ages of <2, 2–4 and 4–6 months were infested with 75 field-collected coconut mites and the population growth was determined up to six weeks after introduction. The populations of coconut mites increased exponentially up to five weeks after introduction and declined thereafter on seedlings of all ages with significant differences among the three groups of seedlings occurring over time. At week 5, a significantly higher mean number (±SE) of coconut mites (20,098 ± 3,465) was bred on 4–6-month-old seedlings than on smaller seedlings, and on the largest seedlings the numbers were highest at all time intervals, except at week 2. Neoseiulus baraki was reared on embryo culture seedlings of the three age groups infested with coconut mites, by introduction of five female deutonymphs and one male, three weeks after introducing coconut mites. Predator numbers progressed significantly over time, but the size of seedlings did not significantly influence the numbers. On all groups of seedlings, the mean number of N. baraki increased up to two weeks after introduction on to seedlings and then declined. Many coconut mites were successfully reared in the laboratory for a longer period by this method and it could also be used as an alternative method to rear N. baraki. Development of this method may contribute to the progress of studies on the biology and ecology of coconut mite and its interactions with natural enemies.     

Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) on strawberry leaves

Neoseiulus californicus (McGregor) is a predatory mite employed for biological control of the agricultural pest Tetranychus urticae (Koch). We explored whether environmental differences, in this case the trichome densities of abaxial leaf surfaces of strawberry cultivars (‘Maehyang’ and ‘Sulhyang’ varieties) affect the functional response of adult female N. californicus preying on immature stages (egg, larva and nymph) of T. urticae. We also evaluated the functional response of N. californicus to eggs of T. urticae at different temperatures (15, 20, 25, 30 and 35°C). We conducted a logistic regression of the proportion of prey consumed as a function of initial prey density to identify functional response types, and used nonlinear least‐squares regression and the random predator equation to estimate attack rates and handling times. The functional response of adult female N. californicus to T. urticae was not influenced by non‐glandular trichomes on abaxial leaves but was affected by temperature. Overall, adult female N. californicus exhibited a type 2 functional response to T. urticae. The handling time of N. californicus was highest (1.9970 h) against T. urticae nymphs. The attack rate did not change much at 15–30°C, but was significantly higher at 35°C. The handling time decreased significantly with increasing temperature at 15–35°C. At 35°C, the attack rate was highest (0.2087) and the handling time was lowest (0.9511 h).     

Functional response of Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) to Bemisia tabaci (Gennadius) on tomato leaves

Bemisia tabaci (Gennadius) is an important invasive pest of vegetables and other horticultural plants worldwide. In this study, the functional response of Neoseiulus cucumeris (Oudemans) to different stages of immature B. tabaci was evaluated under laboratory conditions. Predation experiments were conducted on tomato leaf discs (2.5?cm diameter) over a 24-h period at 26?±?1°C and 65?±?5% relative humidity with a L16:D8 photoperiod. The prey densities ranged from 5 to 90 immature stages (eggs and first- to fourth-instar nymphs) of B. tabaci per leaf disc. The results showed that the egg stage of B. tabaci was the most susceptible prey stage and that the mated female adult mite (3-day-old) was a more effective predator than the male adult mite. The functional response of adult N. cucumeris followed a Type II trend curve as shown in a logistic regression model. Adult N. cucumeris exhibited different predation tendencies towards prey in different stages of immaturity. The daily maximum number of eggs, first-, second- and third-instar nymphs of B. tabaci killed by a single female over a 24-h period (26?±?1°C, 65?±?5% RH and L16:D8 photoperiod) were 8.5, 5.2, 3.0 and 2.1, respectively, whereas the number killed by a single male was 6.0, 4.0, 2.3 and 1.8, respectively. The results of this study could help determine an effective B. tabaci biocontrol measure that employs a natural predator.     

Biological parameters of the predatory mite Cheletomimus bakeri (Acari: Cheyletidae) feeding on Tetranychus cinnabarinus (Acari: Tetranychidae)

Developmental periods of egg, larva and nymphal stages and fecundity as well as predation of Cheletomimus bakeri (Acari: Cheyletidae) feeding on Tetranychus cinnabarinus (Acari: Tetranychidae) were evaluated at different temperatures (15, 20, 25, 30 and 35°C) at 65 ± 10% relative humidity and 16 L: 8D in the laboratory. The development periods of C. bakeri from egg through adult decreased significantly when the temperature was increased from 20°C to 35°C. Egg and total development periods of C. bakeri at 20, 25, 30 and 35°C were 13.86, 7.98, 5.07, 4.08 days and 58.66, 41.51, 21.21, 22.92 days, respectively. The highest numbers of total and daily egg production were found at 20°C and 30°C, respectively. Net reproductive rate (R₀ = 13.29), mean generation time (T = 88.30), gross reproductive rate (GRR = 17.46) and doubling time (DT = 23.66) were the highest at 20°C. The intrinsic rate of increase (r_m = 0.0592) and finite capacity for increase (λ = 1.061) for C. bakeri were the highest at 30°C. Predation of C. bakeri increased throughout the range of prey densities. The highest consumption number of C. bakeri feeding on T. cinnabarinus males per day was 4.63, 4.70 and 4.60 when confined to 40, 80 and 160 individuals, respectively. Our data suggest that C. bakeri does not appear to have much promise for the control of spider mites because of the characteristics of the predator such as slow development period, poor searching capacity and low intrinsic rate of increase.