Life history of the predatory mite Lasioseius athiasae (Acari, Ascidae) on various kinds of food substances: a polypeptide analysis of prey consideration

The predacious ascid mite Lasioseius athiasae Nawar and Nasr was found in association with herbaceous plants, fallen leaves and in debris under deciduous fruit trees. The larvae fed and developed on different prey, such as 'motile stages of the eriophyid grass mite Aceria dioscoridis (Soliman and Abou-Awad), eggs of house fly Musca domestica L., nymphs of the two-spotted spider mite Tetranychus urticae Koch, and eggs of the root-knot nematode Meloidogyne incognita Chitwood. Eriophyids of grasses caused the immature stages to develop faster than did other prey. During the oviposition period, daily consumtion by a female of L. athiasae was 97  A. dioscoridis , four M. domestica eggs, and 10 T. urticae nymphs . The average number of eggs/female per day was 3.21, 1.63 and 1.26 for the above-mentioned prey, respectively. A low rate was recorded on M. incognita eggs (0.35). The intrinsic rate of increase ( rm ) was increased when fed on A. dioscoridis , but decreased on other prey species. The multiplication per generation ( R _o) was 44.73 times in a generation time ( T ) of 17.92 days when fed on eriophyids. The eriophyid grass mite proved to be the more suitable prey. The polypeptide analysis of different prey revealed that A. dioscoridis has the most important contents in both number (11 polypeptides) or total molecular weight (682 kDa).     

Development of Iphiseiodes quadripilis (Banks) (Acari: Phytoseiidae) on pollen or mite diets and predation on Aculops pelekassi (Keifer) (Acari: Eriophyidae) in the laboratory

Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28 degrees +/- 1 degrees C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 +/- 0.47 and 3.5 +/- 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.     

Biology of three species of Agistemus (Acari: Stigmaeidae): life table parameters using eggs of Panonychus citri or pollen of Malephora crocea as food

The biology and life table parameters of Agistemus industani Gonzalez, A. cyprius Gonzalez, and A. floridanus Gonzalez (Acari: Stigmaeidae) were studied under laboratory conditions using two food sources: Panonychus citri (McGregor) eggs or ice plant, Malephora crocea (Jacquin) Schwantes pollen at 25 degrees C. The larval, protonymph, deutonymph, and adult stages of A. industani fed on citrus red mite eggs. All active stages of A. industani, except the larva, fed on all P. citri stages and the larval stage could not feed on P. citri adults. All immature stages of A. industani fed on M. crocea pollen. Agistemus cyprius larvae fed on P. citri eggs and larvae or ice plant pollen. The nymphal stages fed on P. citri eggs, larvae, and protonymphs but not deutonymphs or adults while A. cyprius deutonymphs and adults fed on all P. citri stages. Adult and nymphal stages of A. cyprius fed on ice plant pollen and successfully completed their development while A. floridanus did not. Agistemus floridanus larvae fed only on P. citri eggs, while the other stages fed on P. citri eggs, larvae, and protonymphs. The developmental times from egg to adult for A. industani and A. cyprius when fed M. crocea pollen were 11.3 and 13.4 days, respectively. Agistemus floridanus was unable to complete its life cycle on a diet of only M. crocea pollen. Agistemus industani, A. cyprius, and A. floridanus completed development from egg to adult in 11.7, 13.8, and 10.8 days, respectively, when fed P. citri eggs. The intrinsic rate of increase (r(m)) values for A. cyprius and A. industani were 0.0311 and 0.1201 per day on the pollen diet. The net reproductive rate (Ro) was 3.58 for A. cyprius and 10.07 for A. industani with generation times (T) of 45.2 and 35.1 days, respectively, on the ice plant pollen diet. The r(m) values for A. cyprius, A. floridanus, and A. industani on the P. citri egg only diet were: 0.0562, 0.1001, and 0.1031 per day, respectively. The Ro values for each species fed P. citri eggs only were: 6.36, 7.90, and 18.70 for A. cyprius, A. floridanus, and A. industani and the generation times (T) for each of the three species were: 35.2, 29.9 and 37.8 days, respectively.     

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.     

Prey stage preference and feeding behaviour of Oligota kashmirica benefica (Coleoptera: Staphylinidae), an insect predator of the spider mite Tetranychus urticae (Acari: Tetranychidae)

We studied the prey stage preference and feeding behaviour of the first to third instar larvae and adult females of Oligota kashmirica benefica Naomi (Coleoptera: Staphylinidae), a predator of the spider mite Tetranychus urticae Koch (red form) (Acari: Tetranychidae), on leaves of the kudzu vine (Pueraria lobata (Wild.) Ohwi (Leguminosae)) under laboratory conditions. The number of mites eaten increased with the growth of predator larvae. Third instar larvae preyed on all stages of spider mite, whereas first instar larvae preyed mainly on immobile stages (eggs and quiescent stages). The predator larvae showed two types of foraging behaviour (active searching and ambush behaviour) when targeting the mobile stages (larval, nymph and adult stages of prey). Although no difference was found in the number of prey consumed by adult females and third instar larvae of the predator, the adult females mainly attacked and consumed the immobile stages.     

Euseiusfinlandicus (Acari: Phytoseiidae) as a potential biocontrol agent against Tetranychus urticae (Acari: Tetranychidae): life history and feeding habits on three different types of food

Life history and reproductive parameters of the generalist predatory mite Euseius (Amblyseius) finlandicus (Oudemans) were studied in the laboratory at 25 +/- 1 degrees C, with a 16L:8D photoperiod and 60 +/- 15% RH, to investigate its response to different food sources: an eriophyid mite Aceria sp., tulip pollen Tulipa gesnerana L., and two-spotted spider mite Tetranychus urticae Koch. Total developmental time of the immature stages was the shortest on eriophyid mites, followed by pollen, and then spider mites. Fecundity was highest on pollen (43.69 eggs; 1.63 eggs/female/day), then eriophyid mites (39.73 eggs; 1.37 eggs/female/day) and lowest on spider mites (18.16 eggs; 0.80 eggs/female/day). Intrinsic rate of increase (Rm), net reproductive rate (Ro) and finite rate of increase (lambda) followed the same pattern [pollen (0.168, 27.96 and 1.183, respectively), eriophyid mites (0.153, 20.81 and 1.167), spider mites (0.110, 9.44 and 1.119)]. Mean generation time (days) was the shortest on pollen (19.90), followed by eriophyid mites (20.02), and then spider mites (20.59). Average spider mite larvae consumed by E. finlandicus during immature stages were 9.18 for males and 11.85 for females. Adult E. finlandicus females consumed an average of 166.38 spider mite protonymphs during adult stage compared to an average of 66.55 by males. The number of prey protonymphs consumed per day by females was highest in the oviposition period, lower in the pre-oviposition period and the lowest in the post-oviposition period. The eriophyid mite as a prey recorded the shortest developmental time, while pollen as food recorded the highest oviposition rate in E. finlandicus. The potential of this predator as a biocontrol agent against T. urticae is discussed.     

Life cycle of Amblyomma cooperi (Acari: Ixodidae) using capybaras (Hydrochaeris hydrochaeris) as hosts

The life cycle of Amblyomma cooperi was evaluated under laboratory conditions testing different host species. Larval infestations were performed on chickens (Gallus gallus) and capybaras (Hydrochaeris hydrochaeris). Nymphal infestations were performed on G. gallus, H. hydrochaeris, guinea pigs (Cavia porcellus) and wild mice (Calomys callosus). Infestations by adult ticks were performed only on capybaras. All free-living stages were observed in darkness at 27 degrees C and RH 85%. Capybaras were significantly (p < 0.05) the most suitable hosts for immature ticks, with the highest larval (63.6%) and nymphal (48%) recovery. Larval and nymphal feeding and premolt periods were significantly different (p < 0.05) between ticks fed on different host species. Male nymphs showed premolt period significantly shorter (p < 0.05) than female nymphs. The overall sex ratio of adult ticks was 0.92:1 (M:F). Infestations by adult ticks on capybaras yielded more than 76% of engorged female recovery. Only three out of 33 engorged females fed on capybaras did not lay fertile eggs. The life cycle of A. cooperi in laboratory, reported for the first time, was completed in an average period of 189.4 days. During the premolt period, all A. cooperi engorged nymphs secreted distinct blackish drops, which seem to be inherent to this species. Our results, associated data in the literature, confirm the high suitability of capybaras for the adult stage of A. cooperi and also indicate this animal species as a primary host for immature stages of A. cooperi in nature. On the other hand, the results of larval and nymphal infestation on chickens and guinea pigs suggest that birds and wild guinea pigs, which are also present in the distribution area of A. cooperi in South America, could be potentially infested by A. cooperi immature stages in nature.     

Demographic parameters of Phyllocoptes adalius (Acari: Eriophyoidea) and influence of insemination on female fecundity and longevity

The biology of Phyllocoptes adalius Keifer (Acari: Eriophyoidea) and influence of insemination on female fecundity and longevity were studied. The experiment was conducted at a constant temperature of 25 ± 0.5 °C, 70–80 % RH and 16-h photoperiod. A modified method of mite rearing on detached leaves in closed cells was successfully applied and demonstrated to be efficient for biological studies of eriophyoids. Survival and development duration of the immature stages, as well as fecundity of female and longevity of adults, were calculated. The longest time of development was observed for eggs, which was almost twice as long as that for larvae and nymphs. Egg-to-adult development did not significantly differ between males and females. Survival rate for the immature stages was highest for nymphs (98.2 %), exceeding 86.2 % for overall pre-adult stages. Life table parameters of P. adalius were estimated as follows: mean generation time (T), 15.8 days; doubling time (Dt), 3.3 days; net reproductive rate (R ₀ ), 27.8 female eggs/female; the intrinsic rate of natural increase (r _m ), 0.21 female eggs/female/day; the finite rate of increase (λ), 1.23 female eggs/female/day; and sex ratio (proportion females), 0.82. Our studies indicate that P. adalius has the potential for rapid population increase, becoming one of the most important rose mite species.     

Efficacy,prey stage preference and optimum predator–prey ratio of the predatory mite,Neoseiulus longispinosus Evans (Acari: Phytoseiidae) to control the red spider mite,Oligonychus coffeae Nietner (Acari: Tetranychidae) infesting tea

The predatory mite, N. longispinosus preys up on red spider mite, O. coffeae infesting tea in south India. An attempt has been made to determine the predatory potential, prey stage preference and optimum predator–prey ratio of N. longispinosus under laboratory and green house conditions. When 50 adult female O. coffeae were given, the number of adults reduced by eight days along with an increase in the number of predators. The larvae hatched from the eggs laid by O. coffeae were fed by predatory mite. N. longispinosus preyed up on all life stages with a preference to larvae and nymphs of red spider mite. Predator–prey ratios of 1:33 and 1:50 were effective in lab, and 1:25 was found to be effective in green house. These results revealed that N. longispinosus could be used as a successful biocontrol candidate of O. coffeae in tea through augmentation or mass rearing and field release.     

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.     

双去甲氧基姜黄素对朱砂叶螨的生物活性及作用方式

在室温26℃±1℃、湿度60%～80%、光照14 h条件下,测定了天然植物活性成分双去甲氧基姜黄素对重要植食性害螨朱砂叶螨各螨态的触杀和熏蒸活性,对幼螨、若螨、成螨的驱避活性,以及对雌成螨的产卵抑制活性.采用玻片浸渍法测得双去甲氧基姜黄素对朱砂叶螨雌成螨48 h的LCso为0.433 mg·mL-1.在0.883 mg·mL-1(LC70)的浓度下,双去甲氧基姜黄素对朱砂叶螨不同螨态触杀活性的大小依次为幼螨＞若螨＞成螨＞卵,其中对幼螨24h和48 h的校正死亡率分别为60.0%和83.3%;对朱砂叶螨各螨态的熏蒸作用不明显,024h和48 h的校正死亡率均小于3%;对幼螨、若螨以及成螨均表现出较强的驱避作用,其中对幼螨的效果最好,不同处理时间的驱避率均在85%以上,其次是若螨,对成螨的驱避性相对较差,72 h的驱避率仅为47.8%.同时对雌成螨有明显的产卵抑制作用,处理后120 h产卵抑制率达到89.3%.表明双去甲氧基姜黄素对朱砂叶螨的主要作用方式为触杀、驱避和产卵抑制作用.     

Perspectives for mass rearing of Iphiseiodes zuluagai Denmark & Muma (Acari: Phytoseiidae)

Iphiseiodes zuluagai Denmark & Muma is an important predator of Brevipalpus phoenicis (Geijskes) on citrus in Brazil. The suitability of Tyrophagus putrescentiae (Schrank) as a food source of I. zuluagai in laboratory rearing was investigated at 25.5 +/- 0.5 masculineC, 88 +/- 7% RU and photophase of 12h. Initially, levels of oviposition of the predator fed on eggs were evaluated, as well as the dead or live post-embryonic stages of T. putrescentiae, in a period of 10 days. The daily oviposition rate was 1.3 egg per female when they were fed on eggs on T. putrescentiae, 0.7 egg per female when they were fed on dead post embryonic stages and about 0.3 egg per female when they were fed on live post-embryonic stages. Later, the life table of I. zuluagai was constructed, when eggs of T. putrescentiae were offered to the predators as prey. The immature stages were observed every 8h, to determine the corresponding durations. In the adult phase, the mites were observed every 24h, to determine the reproductive parameters. The intrinsic rate of natural increase (r m) was 0.11 female/ female/day; resulting in a finite rate of increase of 1.11 (l). The net reproductive rate (R0) was 7.1 females/generation, with a mean generation time (T) 18.6 days. The results show that T. putrescentiae is a favorable food source for the development of I. zuluagai.     

Laboratory and glasshouse evaluation of entomopathogenic fungi against the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), on tomato, Lycopersicon esculentum

Forty isolates of entomopathogenic fungi from six genera were assessed against the two-spotted spider mite, Tetranychus urticae, in a single dose, direct application laboratory bioassay on tomato leaflets. Only three isolates caused greater mortality than the control: these were Metarhizium anisopliae 442.99, Hirsutella spp. 457.99, and Verticillium lecanii 450.99. These isolates were assessed in a multiple dose bioassay, together with three isolates cultured from commercial biopesticides as follows: Beauveria bassiana 432.99 (cultured from 'Naturalis-L', Troy Biosciences, Phoenix, TX, USA); Hirsutella thompsonii 463.99 (cultured from 'Mycar', Abbott Laboratories USA); and V. lecanii 19.79 (used in 'Mycotal' Koppert BV, The Netherlands). Beauveria bassiana 432.99, H. thompsonii 463.99, M. anisopliae 442.99, and V. lecanii 450.99 were all pathogenic to T. urticae in this bioassay. In addition, it was found that the mortality caused by B. bassiana 432.99 and Naturalis-L was increased when the mites were exposed to tomato leaflets sprayed previously with conidia suspensions, compared to spraying the mites directly. In a glasshouse experiment, sprays of B. bassiana 432.99, H. thompsonii 463.99, M. anisopliae 442.99, V. lecanii 450.99 and Naturalis-L reduced T. urticae populations in a tomato crop grown according to commercial practice. Naturalis-L reduced T. urticae numbers by up to 97%. In a second glasshouse experiment, single sprays of Naturalis-L and the acaricide fenbutatin oxide (Torq) were compared as supplementary treatments to release of the predatory mite, Phytoseiulus persimilis. Supplementary sprays of fenbutatin oxide reduced the numbers of T. urticae nymphs (80% reduction), while Naturalis-L reduced numbers of T. urticae adults, nymphs and eggs (98% reduction in all three cases). It is concluded that Naturalis-L has the potential to be used against T. urticae on glasshouse tomato crops.     

Influence of prey on developmental performance, reproduction and prey consumption of Neoseiulus californicus (Acari: Phytoseiidae)

The Spical strain of the predatory mite Neoseiulus californicus (McGregor) is used as a biological control agent, but little is known about its preferred prey and host plants in Japan. Here we studied the development, reproduction and prey consumption of the Spical strain when fed on eggs of five different spider mite species deposited on both their laboratory-rearing plant and cherry, on which all five spider mite species developed well. The developmental periods of immature N. californicus females and males were significantly affected by the prey species they fed on, but not by the plants. No difference was found between males and females. The developmental period was shorter on eggs of two Tetranychus species than on eggs of Panonychus ulmi. Immature females had a higher predation rate than immature males. Preoviposition period, oviposition period and the number of eggs laid per female were not significantly affected by either the plants or the type of prey eggs. The postoviposition period and total adult longevity were shorter on eggs of P. ulmi than of the other four prey species, but there was no effect of plant substrate. The postoviposition period of the Spical strain was much longer than that of other N. californicus strains or other predatory mite species: the postoviposition period of the Spical strain was more than three times longer than the oviposition period, accounting for more than 75% of the total adult longevity. This suggests that the females need multiple mating to reach full egg load, but this remains to be tested. Total consumption by N. californicus adults was lower for eggs of P. ulmi than for eggs of the other four species, apparently because of the shorter postoviposition period when fed on eggs of P. ulmi. The intrinsic rates of natural increase (r _m) on the rearing plant did not differ among prey species, whereas those on cherry were significantly different: the value was higher on Tetranychus urticae eggs than on eggs of other species. Only when N. californicus fed on T. urticae eggs, the r _m-values were significantly different between the rearing plant and cherry (higher on cherry). Thus, the Spical strain of N. californicus could feed on eggs of all five spider mite species, deposited on a variety of plants with similar r _m-values, suggesting that it could be successfully used to control spider mites in orchards and various crop fields of Japan.     

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.     

Biological studies of the Australian predatory mite Typhlodromalus lailae (Schicha) (Acari: Phytoseiidae)

Abstract The biology of the Australian phytoseiid mite Typhlodromalus lailae is described from material collected in Western Australia and New South Wales in 1994. At 25°C, when fed on cumbungi ( Typha sp.) pollen, the life cycle is completed in approximately 6 days, with an intrinsic rate of natural increase ( r _m ), of 0.38. Female−male pairs produced a mean total of 44.6 eggs within 22 days of oviposition, with 39% of these females living in excess of 29 days. Females that were deprived of males after first mating stopped laying eggs after 4−9 days, but if another male was added they resumed egg laying and produced close to a full complement of eggs (mean 42 eggs). At 25°C, fecundity on a diet of cumbungi pollen or thrips larvae (first-instar Frankliniella schutzei Trybom) was high, averaging 3.71 and 3.33 eggs per day, respectively, over a 3-day period. The sex ratio was approximately 1.5 females to 1 male. Consumption rate of thrips was also high, with an average of approximately seven first-instar or two second-instar F. schultzei larvae eaten per day. The species was also observed to feed on broad mite, Polyphagotarsonemus latus (Banks), and tomato russet mite, Aculops lycopersici (Massee). No diapause was observed under conditions of 25°C 8 h light and 10°C 16 h dark. Eggs were sensitive to low humidity, with 50% failing to hatch below 71.1% relative humidity. This species is of interest as a candidate biological control agent for thrips, broad mite and tomato russet mite in protected crops.     

Life table and predation of Neoseiulus longispinosus (Acari: Phytoseiidae) on Oligonychus coffeae (Acari: Tetranychidae) infesting tea

Life table and predation of the predatory mite Neoseiulus longispinosus (Evans) on the red spider mite (RSM), Oligonychus coffeae (Nietner), a major pest of tea in India, were studied in the laboratory. Developmental time from egg to adult varied from 4 to 14 days at 30 to 15 °C, respectively; at 35 °C no larva survived. Survival of immature stages was more than 94 % at all temperatures. Threshold temperature for development of immature stages of females and males was 10 and 9.9 °C, respectively, and thermal constant was 84.03 degree-days for females and 80 for males. Sex ratio was female biased and temperature (20–30 °C) had no clear effect on sex determination. Egg hatchability was 73 % at 35 °C and >97 % at lower temperatures. Average number of eggs laid per female/day was higher at 30 °C than at 20 or 25 °C. The highest net reproductive rate (R ₀) was 40.7, at 20 °C. Mean generation time (T) decreased from 28 to 13 days with temperature increasing from 20 to 30 °C. Weekly multiplication (6.5) and intrinsic rate of natural increase (r _m ) (0.268) were highest at 30 °C. Males lived longer than females at every temperature tested. Longevity was highest at 20 °C (50 days for females and 55 for males). Survival and longevity were adversely affected by temperature above 30 °C. Daily consumption of prey increased with the advancement of predator’s life stages; adult females consumed the highest numbers of prey items, preferably larvae and nymphs.     

Development, survival, and oviposition of the rabbit tick, Haemaphysalis leporispalustris (Packard) (Acari: Ixodidae), at constant temperatures

The relationship between development, survival, and oviposition rates, and five constant temperatures is described for the developing and reproductive life stages of the rabbit tick, Haemaphysalis leporispalustris (Packard). Development was most rapid at 29.7 C for egg and larvae, and 35.6 C for nymphs. Survival was greatest between 14.7 and 29.7 C, but was reduced at 35.6 C for eggs and larvae. Oviposition was optimal between 19.9 and 29.7 C with a maximum mean daily oviposition of 253 eggs/female/day on the third day of oviposition at 29.7 C. Maximum mean total eggs per female produced was 1,157 with a range of 277 to 3,327. The total number of eggs produced per female correlated with the weight of the engorged female. Both linear and sigmoid curve equations were used to approximate the relationship between the temperature and development rates of eggs, larvae, and nymphs. The nymphs had the highest heat requirements of the 3 development stages. Comparisons with field host-parasite data indicate that the rabbit tick has a 2-yr life cycle in southwestern Nova Scotia.     

Effects of triflumuron on the two-spotted spider mite,Tetranychus urticae (Acari: Tetranichydae)

The effects of triflumuron on the mortality, fecundity, and fertility of the two-spotted spider mite, Tetranychus urticae, were evaluated in the laboratory. No differences in toxicity for larvae, protonymphs and deutonymphs were observed, but immature stages were 3.8-times more susceptible than adults at the LC₅₀. The compound exhibited a direct contact ovicidal activity influenced by eggs age. 48–72 hold eggs were significantly more sensitive than eggs of the other age classes. No hatch inhibition was observed in eggs laid by treated adult females using a sublethal dose at two physiological times (<12 and 48–72h old). However, fecundity decreased in younger treated females, but it increased in the older-ones. The toxicity for immatures and eggs, and the sublethal effects described suggest that triflumuron could be an interesting incorporation in integrated pest programs of T. urticae. This revised version was published online in July 2006 with corrections to the Cover Date.     

Life-cycle and host specificity of Amblyomma tigrinum (Acari: Ixodidae) under laboratory conditions

Biological data of three generations of Amblyomma tigrinum in the laboratory are reported and the suitability of different host species for immature ticks are compared. Grouping the three generations, infestations by both the larval and nymphal stages were performed on chickens (Gallus gallus), wistar rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus),wild mice (Calomys callosus), dogs (Canis familiaris) and opossums (Didelphis albiventris). Only dogs were used for infestations by adult ticks. Tick developmental periods were observed in an incubator at 27°C and RH 90%. The proportion of engorged larvae recovered from chickens (21.7% of the exposed larvae) was significantly larger (p<0.001) than those from the five mammal species used in the infestations (maximum of 3.1%). A significant larger (p<0.01) proportion of engorged larvae successfully molted after being fed on chickens than on mammal hosts. The proportion of engorged nymphs recovered from chickens (28.8% of the exposed nymphs) was significantly larger (p<0.001) than those from mammal hosts (range: 0–2.1%). Larvae showed similar feeding periods on exposure to different host species, except for those larvae fed on C. callosus, which showed significantly longer (p<0.001) feeding periods. Engorged larvae detachment peaked on the 5^th feeding day, followed by the 6^th day, on all hosts except for C. callosus. Larval premolt periods were similar for engorged ticks exposed to different host species, except for larvae fed on dogs, which showed significantly longer (p<0.001) premolt periods. Host detachment of engorged nymphs peaked on the 6^th feeding day on chickens. Although nymphal detachment on rats peaked on the 8^th day, only 15 nymphs were recovered from this host species. In a sample of 144 F₃ nymphs fed on chickens no significant difference (p>0.10) was found between the feeding or premolt periods of 82 males and 62 females, but female nymphs were significantly heavier (p<0.005) than male nymphs. Sixteen engorged females (61.5% of the exposed ticks) were recovered after being fed on dogs, and all these females laid viable eggs. Chickens, the only avian host, were the most suitable host when compared with the five mammal species. Dogs were demonstrated to be a suitable host for adults of A. tigrinum, which is consistent with, several reports of adult A. tigrinum ticks parasitizing dogs in different areas of South America. Our results reinforce that in these same areas avian species are the major hosts for immature stages of this tick species. This revised version was published online in July 2006 with corrections to the Cover Date.