Estimation of prey consumption of a mantid,Paratenodera angustipennis (S.) in a natural habitat

Using a relationship between prey consumption and growth rate, field prey consumption of adults of Paratenodera angustipennis (S.) in a paddy field was estimated. Since a great number of grasshoppers (Oxya japonica) lived in the research area and the mantids had frequently eaten O. japonica, we presumed that they consumed only O. japonica. As a result, it was estimated that average prey consumptions for 6 days were 406 mg for the females and 23 mg for the males. From the result of this estimation and the feeding rhythm of the mantids, it is concluded that each female captured one grasshopper on average every a few days. By comparing this actual feeding level of P. angustipennis with those of other predacious arthropods, characteristics of P. angustipennis as a predator were discussed.     

Prey preference and consumption capacity of Nephus arcuatus (Coleoptera: Coccinellidae): the influence of prey stage,prey size and feeding experience

This study examined the feeding habits of Nephus arcuatus Kapur (Coleoptera: Coccinellidae), an important predator of mealybugs in south-western Iran. The consumption capacity of male and female N. arcuatus adults was determined by their feeding on eggs, first-instar nymphs, and adult females of two destructive mealybugs, Nipaecoccus viridis (Newstead) and Planococcus citri Risso, over a 24-h period. N arcuatus consumed significantly more first-instar nymphs than eggs, and more eggs than female adults of both prey species. In addition, we also studied the developmental stage prey preference of adults reared on either N. viridis or P. citri and found that the prey preference of females did not change with the developmental stage of the mealybug. Meanwhile, the males reared on either N. viridis or P. citri showed a significant preference for the first-instar nymphs of P. citri over first-instar nymphs of N. viridis, while a preference for the eggs or adult females of these two mealybugs was not observed. This selection of first-instar nymphs by males was not tied to its previous feeding experience. Our findings suggest that prey stage, prey size and previous feeding experience had no effect on the prey selection of N. arcuatus, making it a good candidate for the biological control of mealybugs.     

Evaluation of the role ofMicrovelia douglasi atrolineata (Bergroth) (Heteroptera: Veliidae) as predator of the brown planthopperNilaparvata lugens (Stål) (Homoptera: Delphacidae)

The biology of the veliid bug M. d. atrolineata, its predatory behavior, and the effects of plural hunting were studied to evaluate its role as a predator of the brown planthopper Nilaparvata lugens in the Philippines. The probability of planthoppers falling onto the water surface and provision of habitat continuity was measured by a sticky trap placed at the base of rice hills in a greenhouse and in paddy fields. The developmental period of immature stages combined was 21 days. If given prey, females laid 25 eggs on the average during an adult life span of 18 days. Starved adults could survive for only 3–5 days. The functional response to prey density was sigmoid, and the maximum number of prey killed was 7 per day. Prey feeding was completed in 12–36 min. The percentage of successful prey attacks averaged 5–8%, decreasing with higher (and larger) developmental. stages of prey, but adult prey were found the soonest. Plural hunting increased the probability of capturing prey by as much as 2.5 times that by individual hunting. Late-instar nymphs, which may be more active, fell from rice hills in a greenhouse more than early-instar nymphs, and the number falling increased with density. In the field the percentage of planthoppers falling to the water in 1 day varied considerably, from 1% for nymphs in one field to 67% for adults in another field. On the basis of work described above and given the high density of veliid predators in flooded paddy fields of tropical Asia, M. d. atrolineata is considered one of the most important natural enemies of the brown planthopper.     

Pick-up lines: cues used by male crab spiders to find reproductive females

The low population density of the crab spider Misumena vatiaand the high percentage of gravid adult females begs the question,how do adult males find reproductive females? We explored oneof the potential mate-locating tactics of adult males, theirline-following behavior. M. vatia do not build webs; however,they do lay down silken lines during their movements. In boththe field and the laboratory, adult males (but not juvenilemales) regularly followed lines of other individuals, as wellas their own, sometimes multiple times. However, they did notdistinguish the direction in which lines were laid, and theyeven followed lines of other species. Males responded mechanicallyto these lines, but not chemically. They followed lines ofpenultimate and adult virgin females, as well as new and old lines, with similar high frequency. Neither washing the lineswith water nor washing them with acetone (to remove possiblewater-soluble or organically soluble pheromones) affected theirchoice of lines. Due to the low activity of females, theirlines may be several days old, over which time any possible chemical information would likely dissipate. Therefore, pheromonesseem unlikely to aid males searching for unmated adult females.Nevertheless, even searching males that follow lines largelyindiscriminately should derive a benefit because concentrationsof lines could denote the presence of females and thereby maximizenumbers of females encountered.     

Age difference in activity pattern of Japanese monkeys: Effects of temperature,snow, and diet

Air temperature, snow depth, and diet composition were found to affect the activity budgets of 1 ∼ 2-year-old, 3 ∼ 4-year-old and adult female (>5 years old) Japanese monkeys (Macaca fuscata) in the Shimokita Peninsula. They spent more time resting as the air temperature decreased. They spent less time moving on the ground, so that they moved shorter distances, where the snow was deep. However, they spent more time moving on the ground as they fed more on fruits and seeds. Adult females moved mainly on the ground, while 1 ∼ 2-year-olds moved on the tree branches as well as on the ground. Adult females increased their time moving on the tree branches where the snow was deep but 1 ∼ 2- and 3 ∼ 4-year-olds did not. The 1 ∼ 2- and 3 ∼ 4-year-olds but not adult females increased their feeding time as they fed more on buds and barks containing abundant fiber. We hypothesize that the large body size of adult females may constrain them to move mainly on the ground, and might enable them to choose energy saving tactics more easily.     

Size and sex of cricket prey predict capture by a sphecid wasp

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Macronutrient intake affects reproduction of a predatory insect

Prey quality has previously been shown to affect the growth and reproduction of predatory arthropods, however relatively little is known about the specific nutrients responsible for these effects. We tested if the macronutrient content (i.e. lipid and protein) of live prey affected mate attraction, reproductive behavior, egg production and nutrient reserves of adult female praying mantids, Pseudomantis albofimbriata. Females on a high‐protein diet produced more than twice as many eggs as females on a high‐lipid diet despite being fed the same overall biomass of prey. Furthermore, the lipid and protein composition of eggs and the female body was directly related to the diet that females were fed (i.e. high lipid content on the high‐lipid diet). Even more striking was the effect of diet treatment on the number of males attracted to females – only one male was attracted to females on the high‐lipid treatment and 56 males were attracted to females on the high‐protein treatment. Although it is not unexpected that females with more eggs would attract more males, the extreme nature of this difference is certainly surprising because previous studies have shown that females with only a couple of eggs can attract multiple males. Hence, our results suggest that female pheromone production may be affected by the quality/nutritional composition of eggs rather than simply the number of eggs. We found no significant difference in any of the other behaviours measured during mating trials, including the frequency of sexual cannibalism. The positive effects of prey protein content on mate attraction and egg production suggest that praying mantids might be expected to choose more protein‐biased prey in nature or, if prey choice is limited, to have higher reproductive output or population growth in communities dominated by protein‐rich prey.     

Effect of resource gradient on age and size at maturity and their influence on early‐life fecundity in the predatory Asian lady beetle,Harmonia axyridis

Variation in food availability impacts the performance of insects in terms of their size and age to maturity and fecundity. Age at maturity determines how quickly individuals in a population can start to reproduce and how much they can reproduce. Results from studies on various insect species show that food availability influences the size and fecundity of adult females. It is predicted that under poor growth conditions, variation in size is low, but variation in age at maturity is considerable. This prediction was examined in a widely distributed lady beetle species, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), a predator of aphids and coccids. Using a food gradient from low to high aphid prey density, performance of females that were reared on excess food was recorded for pre‐reproductive duration, size at reproductive maturity, number of aphids consumed, and fecundity in the first 10 days of their reproductive period. Results suggested that female H. axyridis that were reared on surplus food when kept at low prey density (poor growth condition) took, on average, three times longer to attain maturity and produced, on average, 14 times fewer eggs than females that were also reared on surplus food, but kept at high prey density (good growth condition). Females performed best at a prey density of 30 aphids per female per 150 cm². Results suggested that the current food availability significantly influenced the age and size of females at maturity and their fecundity. Age and size at maturity of female lady beetles showed non‐linear responses to prey density as well as the occurrence of a minimum size of females, below which H. axyridis females fail to mature. The steep slope recorded at lower prey densities suggests relatively high variation in age at maturity but low variation in size.     

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.     

Allocating time between feeding, resting and moving by the two-spotted spider mite, Tetranychus urticae and its predator Phytoseiulus persimilis

This study characterizes the timing of feeding, moving and resting for the two-spotted spider mite, Tetranychus urticae Koch and a phytoseiid predator, Phytoseiulus persimilis Athias-Henriot. Feeding is the interaction between T. urticae and plants, and between P. persimilis and T. urticae. Movement plays a key role in locating new food resources. Both activities are closely related to survival and reproduction. We measured the time allocated to these behaviours at four ages of the spider mite (juveniles, adult females immediately after moult and adult females 1 and 3 days after moult) and two ages of the predatory mite (juveniles and adult females). We also examined the effect of previous spider mite-inflicted leaf damage on the spider mite behaviour. Juveniles of both the spider mite and the predatory mite moved around less than their adult counterparts. Newly emerged adult female spider mites spent most of their time moving, stopping only to feed. This represents the teneral phase, during which adult female spider mites are most likely to disperse. With the exception of this age group, spider mites moved more and fed less on previously damaged than on clean leaves. Because of this, the spider mite behaviour was initially more variable on damaged leaves. Phytoseiulus persimilis rested at all stages for a much larger percentage of the time and spent less time feeding than did T. urticae; the predators invariably rested in close proximity to the prey. Compared to adult predators, juveniles spent approximately four times as long handling a prey egg. The predator-prey interaction is dependent upon the local movement of both the predators and prey. These details of individual behaviours in a multispecies environment can provide an understanding of population dynamics.     

Predation,oviposition and longevity of the predacious mite,Agistemus exsertus Gonzalez at different prey densities of Tetranychus urticae Koch (Acari: Stigmaeidae,Tetranychidae)

The relation between some biological aspects of the predatory mite, Agistemus exsertus Gonzalez and nymph densities of Tetranychus urticae Koch was studied in the laboratory. Predation and oviposition of A. exsertus showed Holling's Type II functional and numerical responses to changes in prey density. The total predation by A. exsertus females initially averaged 79.42 nymphs/female at 2 prey nymphs/day, significantly increased to a maximum average of 208.92 nymphs/female at 10 nymphs/day and gradually decreased to 90.92 nymphs/female at 30 prey items/day. Similarly, the predator significantly deposited total averages of 14.75, 76.42 and 34.33 eggs/female at 2, 10 and 30 nymph densities/day, respectively. The preoviposition and oviposition periods as well as longevity of A. exsertus significantly shortened with increasing prey densities.     

Signalling conflict between prey and predator attraction

Predators may utilize signals to exploit the sensory biases of their prey or their predators. The inclusion of conspicuous silk structures called decorations or stabilimenta in the webs of some orb‐web spiders (Araneae: Araneidae, Tetragnathidae, Uloboridae) appears to be an example of a sensory exploitation system. The function of these structures is controversial but they may signal to attract prey and/or deter predators. Here, we test these predictions, using a combination of field manipulations and laboratory experiments. In the field, decorations influenced the foraging success of adult female St. Andrew’s Cross spiders, Argiope keyserlingi: inclusion of decorations increased prey capture rates as the available prey also increased. In contrast, when decorations were removed, prey capture rates were low and unrelated to the amount of available prey. Laboratory choice experiments showed that significantly more flies (Chrysomya varipes; Diptera: Calliphoridae) were attracted to decorated webs. However, decorations also attracted predators (adult and juvenile praying mantids, Archimantis latistylus; Mantodea: Mantidae) to the web. St. Andrew’s Cross spiders apparently resolve the conflicting nature of a prey‐ and predator‐attracting signal by varying their decorating behaviour according to the risk of predation: spiders spun fewer decorations if their webs were located in dense vegetation where predators had greater access, than if the webs were located in sparse vegetation.     

Vitellogenesis and oocyte development in azadirachtin-induced fifth-instar overage nymphs of Locusta migratoria (L.)

Injection of azadirachtin into females of Locusta migratoria at the beginning of the last nymphal instar prevented molting to the adult stage, and many of these locusts survived for long periods as overage fifth-instar nymphs. Overage female nymphs synthesized vitellogenin; maximum vitellogenin content in their hemolymph was 6–7 times higher than that found in normal adult females. The overage female nymphs developed vitellogenic oocytes, but development was retarded to some extent: although vitellogenin did accumulate in the proximal oocytes, their maximum average length was only about 2.8 mm (compared to 6.2 mm in normal adult females) and extensive oocyte resorption was observed. Thus, attainment of adult competence of the organs and processes involved in female reproduction is independent to a considerable extent from the process of overt adult morphogenesis.     

Laboratory evaluation of predation rates of two native natural enemies on the exotic pest Bagrada hilaris

Laboratory studies were conducted to determine the consumption rates of two native predators found attacking the exotic invasive stink bug Bagrada hilaris (Burmeister) (Hempitera: Pentatomidae) in field plots in New Mexico, USA. Individual field‐collected adults of the spined soldier bug, Podisus maculiventris (Say) (Hempitera: Pentatomidae) and the soft‐winged flower beetle, Collops vittatus (Say) (Coleoptera: Melyridae), were provided daily with fixed numbers of different life stages of B. hilaris under controlled conditions. Consumption rates were recorded daily for ten consecutive days for a total of 20 adult P. maculiventris and 20 adult C. vittatus per prey life stage. For P. maculiventris, predation rates were obtained in relation to adult, third and fifth instar prey, and for C. vittatus for first, second and third instar prey. On average, predation on third and fifth instar B. hilaris nymphs by P. maculiventris was 0.6 ± 0.1 and 0.9 ± 0.1 per day respectively. Predation rates on adults were slightly higher (1.3 ± 0.1 per day), with female prey being consumed at a significantly higher rate than male prey when three mating pairs of B. hilaris were provided per day (0.8 ± 0.1 females per day vs. 0.5 ± 0.1 males per day). Collops vittatus adults provisioned daily with 20 first instar B. hilaris nymphs killed a mean total of 4.7 ± 0.4 and 9.3 ± 0.6 prey each day (for male and female beetles respectively), with only approximately half that number of prey being fully consumed. Partial consumption of prey by this species was also observed with second and third instar nymphs, but to a lesser degree. Female beetles consumed significantly more prey than did male beetles when fed first and third instar B. hilaris, but not when given second instar prey.     

The searching behaviour of Anthocoris confusus (Reuter) in relation to prey density and plant surface topography

• 1 The searching behaviour of A.confusus females was investigated in an artificial arena.
• 2 Females showed an increase in the frequency of turning movements following feeding and this concentrated search in a small area. As a result more prey were found in areas where prey distribution was clumped.
• 3 If no prey was encountered within 5–8 min the search track straightened out.
• 4 First and second instar nymphs searching on broad bean plants moved faster on the undersides of leaves which were the sites most likely to support aphid populations. A considerable proportion of available time was wasted in periods of inactivity.
• 5 It was concluded that while plant topography strongly influences search pattern, the underlying trend demonstrated in these experiments was of advantage to predators searching for colonial prey.

     

Biology of Tupiocoris cucurbitaceus (Hemiptera: Miridae), a predator of the greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) in tomato crops in Argentina

The predator Tupiocoris cucurbitaceus is frequently found attacking Trialeurodes vaporariorum in greenhouses without pesticide applications in Argentina. The objective of these studies was to evaluate some biological characteristics of this species fed on three types of diet (whitefly nymphs, Sitotroga cerealella eggs and a mix of both) and on two host plants (tomato and tobacco), under controlled experimental conditions. Preimaginal developmental time for female and male bugs was shorter in the presence of whiteflies than with only moth eggs. Females lived longer when they ate only whitefly nymphs compared to a mixed diet or only moth eggs. The amount of adult descendants was greater when bugs could eat whiteflies, regardless of the presence of S. cerealella. Embryonic development time, male longevity and sex proportion were not affected by the diet or the host plant. Prey consumption was evaluated for three T. cucurbitaceus life history stages (fourth/fifth instar nymphs, female and male adults) on two types of prey (whitefly nymphs and S. cerealella eggs). On tomato, females were more voracious than males and nymphs. On tobacco, adults and nymphs consumed more S. cerealella than T.vaporariorum nymphs, but again, bug females preyed more than males and nymphs. Results demonstrate that T. cucurbitaceus can survive, develop and reproduce normally using both T. vaporariorum and S. cerealella eggs as prey on tobacco or tomato plants. This information can be useful for managing this predator against T. vaporariorum through conservative or augmentative biological control strategies.     

Some factors affecting reproduction and sex-ratio of the predacious mite Amblyseius deleoni (Muma and Denmark) (Acari: Phytoseiidae)

Abstract

Several factors were examined to determine their effect on the reproduction and sex ratio in the predacious mite Amblyseius deleoni (Muma and Denmark), in the laboratory. The factors investigated included multiple matings, duration of copulation, capacity of male for mating in excess of females and age of mating females and males. The factors included also, the host plant leaf texture, food deprivation during immature and adult stages, and prey (Tetranychus urticae Koch) density. The results indicated that females of A. deleoni require multiple matings to maximize their reproductive potential, also when copulation was allowed for increasing periods of time, there was a gradual increase in total egg production and oviposition period. A male showed a high reproductive ability for more than 15 days and was able to mate more than once in excess of females. Age of females has an influence on fecundity and sex ratio; old females decreased egg production and produced proportionally more male progeny compared with young females. Similarly, the highest number of eggs deposited per female A. deleoni was reported, when female mated with a young male (0-day old). In addition, males of A. deleoni (at any age) were able to inseminate the females. Results from host plant leaf texture indicated that guava leaf gave the highest reproduction rate, while the fig leaf gave the least female fecundity. Neither the reproductive rate nor the sex ratio of the progeny of females crossed by normal or experimental males had been influenced by the food deprivation during immature stages. A significant lower fecundity was recorded on female's A. deleoni when exposed to different food deprivation programmes during adult stage. The number of eggs laid by the predator female increased with increasing prey density of T. urtice to a maximum of 2.04 eggs deposited per day at a prey density of 30 protonymphs of T. urticae as a prey. As the level of prey density was increased, there was a shift in sex ratio towards an increased proportion of females.     

Searching behaviour and mate recognition by males of the two-spot ladybird beetle, Adalia bipunctata

Abstract. 1. Adult males of the two-spot ladybird beetle, Adalia bipunctata , did not show a functional response to increase in aphid abundance and consumed markedly fewer aphids than do the females.
2. At high densities of prey, females spent more time in area-restricted search than when prey was scarce. Males were always less active than females and they did not respond to an increase in prey abundance by a change in searching behaviour.
3. After a brief encounter with a female, a male showed area-restricted searching behaviour. This behaviour occurred in response to encountering a female's elytra and in particular to a chloroform-soluble component (sex pheromone) present on or in the elytra.
4. Males needed to encounter a female in order to respond to her presence, which indicated the pheromone is a contact pheromone.
5. The searching behaviour of males appeared to be mainly directed towards locating females; that of females towards locating aphids. This difference between the sexes should be taken into account when quantifying the predatory response of ladybirds to aphid abundance in the field.     

Host-searching and mating in an outbreeding parasitoid wasp

Abstract.

• 1 Female parasitoid wasps (Hymenoptera) must search for hosts to reproduce, but only require mates if their broods are to contain female progeny. In outbreeding species, females locate mates after dispersal from the emergence site. Unmated females may therefore face a trade-off between searching for hosts and searching for mates, if hosts and mates are spatially separated.
• 2 In the outbreeding parasitoid Bracon hebetor Say (Hymenoptera: Braconidae), males and females are spatially segregated in the field. Females are found primarily below the surface of stored corn where they search for hosts, whereas males are found on or above the surface.
• 3 Wasps placed in laboratory observation chambers designed to mimic B.hebetor's stored corn habitat distributed themselves in a manner consistent with field observations. Males remained on the surface of the grain, whereas females moved below the surface to attack hosts.
• 4 In the laboratory, female distribution was influenced by their mating status, the presence of males or hosts, and female age. Virgin females were more reluctant to move into the corn than were mated females, younger females foraged deeper than older females, and all females moved deeper into the com when males were present.
• 5 10% of all females did not mate even when males were present in the chambers, a percentage consistent with previous observations from the field. If B.hebetor faces a trade-off between host-searching and mate-searching, the trade-off seems to be part of 'split sex ratio strategies', with some females remaining constrained to producing only male offspring.

     

Population behaviour of the southern green stink bug,Nezara viridula,with special reference to the developmental stages of early-planted paddy

Population behaviour of adults and 5th-instar nymphs of Nezara viridula L. was analysed by means of the marking-and-recapture method in an early-planted paddy field. The field contained five varieties of rice which differend in growth states. It was estimated that a total of more, than 7,000 adults of the first generation, in which at least 3,000 were females, invaded the field from early July to middle August. Egg-mass census data, however, indicated that only 10 per cent or less of the females participated in egg-laying. This was largely due to the, low rate of adult survival. The adults preferred younger plants, for both feeding and oviposition. The method described byIwao et al. (1966) permitted estimate that 3,300–3,400 of the 5 th-instar nymphs and 1,100–1,200 of the adults of the second generation were produced from 298 egg-masses (25, 700 eggs); while 95–6 per cent of the individuals were thought to have died before reaching adulthood. Most of the 5 th-instar nymphs moved less than 4 m in three days as long as the condition of food plants remained suitable, but they tended to move more towards younger plants when those on which they lived became too mature. The apparent survival rate of the second generation adults was very low, probably due both to a rapid emigration and a high mortality of newly-emerged adults.