Whitefly Pupae Research Articles

Effect of Different Management Treatments on Whitefly Parasitization by <i>Encarsia</i> spp. under Field Condition on Cotton

Effect of different management modules on Encarsia spp. at different intervals during Kharif, 2015 was studied. Maximum parasitization 32.28 and 31.50% was recorded in T12 [Control (without water spray)] in both the intervals (5- and 10-days interval) followed by 30.30 and 29.85% in T2 nimbecidine (six sprays at 5 days interval) + Yellow sticky trap in both the intervals, respectively. While minimum parasitization (15.02 and 14.91%) was recorded in T5 [First spray of dimethoate followed by imidacloprid, thiamethoxam, triazophos, imidacloprid and thiamethoxam (at 5 days interval)] and T8 [first spray of nimbecidine followed by dimethoate, triazophos, novaluron (at 10 days interval)], respectively. It is concluded that high whitefly pupae parasitization was found in neem treated plots than insecticide treated plots. So, nimbecidine was found relatively less toxic and much safer to natural enemy.

Effect of White Champa Leaf Extract (Plumeria acuminata) on White Fly Eclosion (Aleurolobus barodensis Maskell, Hemiptera; Aleyrodidae)

The white fly explosion might be occurred on the flooded fields and lack of nitrogen fertilizer. Some control methods have to be conducted to prevent further losses. The use of biopesticide was known to be easier, cheaper and environmental friendly control methods. Therefore the aim of this experiment was determining the effect of white champa leaf extract (Plumeria acuminata) as a biopesticide on sugarcane white fly eclosion (Aleurolobus barodensis). Experiment was conducted in the laboratory, using a completely randomized design with 6 treatments of P. acuminata leaf extract concentrations, that were 0% (control), 10%, 20%, 30%, 40% and 50%, and was replicated 4 times. The results showed that P. acuminata leaf extract could be used to control sugarcane white fly. The effective leaf extract concentration was 40%. The results also proved that P. acuminata leaf extract killed the white fly pupae instead of delaying their eclosion.

Temperature-dependent functional response of Nesidiocoris tenuis (Hemiptera: Miridae) to different densities of pupae of cotton whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)

The effect of temperature on the functional response of female adults of Nesidiocoris tenuis Reuter to different densities of Bemisia tabaci (Gennadius) pupae was assessed. Three constant temperatures (15, 25, and 35°C) and six prey densities (5, 10, 20, 35, 50, and 70) were tested over a 24-h period. Nesidiocoris tenuis exhibited a type II functional response at 15 and 25°C, and a type III response at 35°C. The number of prey consumed by the predator increased with increase in the prey density at all temperatures. Temperature influenced attack rates and handling times. The highest attack rate occurred at 35°C at high densities (35, 50, and 70 prey) and the lowest handling time was recorded at 35°C. The maximum attack rates (T/Th) were 17.13, 42.12, and 45.07 whitefly pupae per day at 15, 25 and 35°C, respectively. As a result, the value of a/Th indicates that N. tenuis was relatively more efficient in attacking B. tabaci at 35°C than at lower temperatures. Results suggest that the ability of N. tenuis to detect and consume B. tabaci over a broad range of temperatures, especially high temperatures (25-35°C), makes this mirid a good candidate for the biological control of whiteflies in warm environments, such as greenhouses.

Patch Retention Time in an Omnivore, Dicyphus hesperus is Dependent on Both Host Plant and Prey Type

We examined patch residence times for an omnivorous predator, Dicyphus hesperus on a variety of plants and prey. Individual D. hesperus were placed in cages containing either mullein, tomato, pepper or chrysanthemum plants, and either no prey, Mediterranean flour moth eggs, greenhouse whitefly pupae or two-spotted spider mite adults. Patch residence times were typically greater than 24 h. The probability of remaining on the patch was greatest on mullein and tomato, followed by chrysanthemum and least on pepper, whereas probability of remaining on the patch was greatest when flour moth eggs were present, and least when no prey were available. Patch residence time in D. hesperus was determined by both the prey, and the species of plant, in an independent fashion. Our results reinforce the notion that for omnivores, the patch itself is as important as the prey that it harbors.

Comparison of prey consumption by Dicyphus tamaninii reared conventionally, and on a meat-based diet

The zoophytophagous predator Dicyphus tamaninii Wagner (Heteroptera: Miridae) has been successfully reared for more than five generations on a meat-based diet, and in the absence of a plant as a substrate for oviposition and feeding. We compared the predation efficiency of D. tamaninii produced on this diet with those reared conventionally on Ephestia kuehniella eggs (Zeller) (Lepidoptera: Pyralidae) and tobacco plants. Their performances were evaluated on two prey, the greenhouse whitefly Trialeurodes vaporariorum West- wood (Homoptera: Aleyrodidae) and the cotton aphid Aphis gossypii Glover (Homoptera: Aphididae). Their tendency to cannibalistic behaviour was also evaluated. Nymphs of D. tamaninii produced on the meat diet consumed a similar number of greenhouse whitefly pupae after 24 and 48 hours to nymphs reared by the conventional method. Diet-reared females consumed significantly more whitefly pupae after 24 and 48 hours than control females. When the cotton aphid was offered, diet-reared D. tamaninii nymphs and females consumed similar numbers of prey to control D. tamaninii. There was no significant increase in cannibalistic behaviour of diet-reared D. tamaninii after 3 and 5 days of interaction. These results show that, after five generations, the predation efficiency and the tendency to cannibalism of meat-reared D. tamaninii is similar to that of conventionally-reared individuals.

Functional Response of Four Heteropteran Predators Preying on Greenhouse Whitefly (Homoptera: Aleyrodidae) and Western Flower Thrips (Thysanoptera: Thripidae)

The mirid bugs Dicyphus tamaninii Wagner and Macrolophus caliginosus Wagner and the anthocorid bugs Orius majusculus (Reuter) and O. laevigatus (Fieber) are abundant generalist predators in unsprayed vegetable crops of the Spanish Mediterranean coast. We evaluated the functional response of these predators to greenhouse whitefly pupae and western flower thrips larvae (second instar) on cucumber leaf disks in the laboratory. Parameters of the random-predator equation obtained were compared among all predator–prey combinations to determine the potential role of the predators in the biological control of both pests in cucumber. D. tamaninii was efficient at consuming whitefly pupae at high and low densities and thrips at high densities, and took less time to handle either of these prey than did the other predators. Anthocorid bugs were efficient at consuming thrips at low and high densities, but did not performed well as predators of whiteflies. M. caliginosus was less efficient when consuming whiteflies but performed better when preying on thrips. It is concluded that D. tamaninii may have a good action in the control of both greenhouse whitefly and western flower thrips, whereas M. caliginosus and both Orius species may be slower in controlling whitefly and be similarly efficient in consuming western flower thrips.

Distribution and Sampling of Bemisia argentifolii (Homoptera: Aleyrodidae) and Eretmocerus eremicus (Hymenoptera: Aphelinidae) on Cantaloupe Vines

Studies were conducted to examine the spatial distribution of immature Bemisia argentifolii Bellows ' Perring and immature Eretmocerus eremicus Rose ' Zolnerowich on cantaloupe vines and to develop efficient sampling plans. More B. argentifolii eggs were found on the 3rd leaf from the terminal of a cantaloupe vine than on any other leaf. The density of whitefly nymphs peaked at leaf position 8, whitefly pupae (large 4th instars) peaked at leaf position 11, and immature E. eremicus peaked at leaf position 14. We looked at 4 parameters to describe the distribution of whitefly and parasitoid life-stages among the various leaf positions as follows: (1) median leaf position, (2) the leaf position with the highest percentage of a particular stage, (3) the leaf position where insect counts were best correlated with counts on the entire vine, and (4) the coefficient of variation (CV). All 4 distribution parameters changed throughout the season. In general the leaf positions described by the 4 distribution parameters increased (i.e., were further from the terminal) until the middle of the season when they began to decline. Across the entire season, the 4 distribution parameters for whitefly eggs were associated with leaf positions 3, 4, and 5; for whitefly nymphs with leaf positions 7, 8, and 10; for whitefly pupae with leaf positions 11 and 12; and for immature parasitoids with leaf positions 11, 13, and 14. Based on considerations of cost and precision, it was most efficient to sample leaf 3 for whitefly eggs, leaf 8 for whitefly nymphs, leaf 11 for whitefly pupae, and leaf 14 for immature parasitoids. Using the Taylor power law, density-dependent minimum sample sizes (number of leaves per field) necessary to achieve a predetermined statistical precision (mean ± SE) were estimated. Over a broad range of densities, 50 leaves per field are adequate to achieve a precision of 0.20–0.25 for all life stages. We also provide estimates of the optimum number of leaves to collect per vine based on the within-vine and between-vine variability and the costs (time) associated with counting whiteflies and moving to another vine.

Classical biological control of ash whitefly: factors contributing to its success in California

The ash whitefly, Siphoninus phillyreae, invaded California in 1988 rapidly spreading throughout the state and infesting several species of ornamental trees and shrubs. Released Encarsia inaron rapidly established populations and spread throughout areas occupied by ash whitefly. We examined whether dispersal and overwintering ability could play a role in the extraordinary success of this parasitoid and we measured the impact of released parasitoids using a new method at a single location in northern California. The dispersal ability of E. inaron was examined by releasing two hundred and fifty adults 25 July 1991 into a single tree in a 1 ha pomegranate orchard near Brentwood, California. Based on yellow sticky card traps, the adult population spread at least 45 m from the release tree within 9 weeks of release. Over the same period of time the parasitoid population increased 64 fold. Impact was determined by measuring the number of ash whitefly adults produced in the absence and presence of E. inaron over 12 months. The production of whitefly adults, measured by the number of pupae entering the adult population, was reduced to very low numbers one year following the establishment of the parasitoid. Production of E. inaron adults increased rapidly, then decreased following the drop in production of ash whitefly adults. Duff of flowering pear trees was collected from under sample trees in mid winter to determine whether ash whitefly could survive on fallen leaves. Over fifty percent of adults emerged from whitefly pupae on leaves within 12 days of collection.

The effect of nitrogen fertilizer applied to Euphorbia pulcherrima on the parasitization of Bemisia argentifolii by the parasitoid Encarsia formosa

AbstractMore wasps of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were found on fertilized poinsettias, Euphorbia pulcherrima (Willd.) (Euphorbiaceae), than on non‐fertilized plants. Parasitization of Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) by E. formosa was higher on plants treated with calcium nitrate than with ammonium nitrate or on control plants. In a no‐choice test, host feeding by E. formosa was higher when hosts were on fertilized plants than when hosts were on control plants. The nitrogen content of whitefly pupae reared on plants treated with ammonium nitrate was higher than those on calcium nitrate‐treated plants.Variability in the parasitization of B. argentifolii by E. formosa appears to be due to host plant‐mediated differences in the whiteflies. E. formosa may be influenced by the nutritional suitability of the host, which influences whether wasps continue to oviposit, feed, or disperse.

Residence times of the whitefly parasitoid Encarsia formosa Gahan (Hym., Aphelinidae) on tomato leaflets

AbstractIndividual Encarsia formosa parasitoids were observed continuously on either clean, honeydew‐contaminated or whitefly‐infested tomato leaflets until the parasitoids flew away. The residence time on clean leaflets was about 20 min at 20, 25 and 30°C, and was the same on infested leaflets when no hosts were encountered. Encounters with unparasitized and parasitized whitefly larvae, and contact with honeydew prolonged the residence time of the parasitoid on the leaflet. Even when many parasitized black whitefly pupae (unsuitable hosts) were encountered and rejected, the parasitoid was still arrested on that leaflet. Encarsia formosa's walking pattern seemed to be random, and parasitoids showed no preference for searching on the upper or lower leaf side when no hosts were encountered. There is also no preference for the edge or for the middle of a leaf. Walking and flight activity of the parasitoids was hardly observed at 15 and 18°C. Many parasitoids became inactive during periods when the barometric pressure decreased but did not when it was stable or increasing.

The influence of normal and low-rate application of insecticides on populations of the cotton whitefly and melon aphid and associated parasites and predators on cucumber

Studies were conducted in cucumber fields to evaluate the standard and reduced dosage rates of 5 insecticides for control the cotton whiteflyBemisia tabaci (Genn.) and melon aphidAphis gossypii Glov. and effect of insecticide application on associated parasites and predators. Eggs of whitefly appeared to be less susceptibility to all treatments (max. 66% reduction) than larval and pupal stages. Populations of larval and pupal stages of whitefly were significantly reduced in all treated plots. For example (larvae on day 10 after treatment with ethiofencarb, diafenthiuron, and chlorpyrifos methyl 67, 50, and 68% pupae 68, 69, and 75%). Two aphelinid parasitoids,Eretmocerus mundus Mercet andProspaltella lutea Masi, were the most primary important parasitoids of the whitefly pupae in all test plots. Percent parasitism, in most treated plots, were slightly affected as a result of insecticide application. However, all tested insecticides and dosage rates caused severe suppression of emergence of adult parasitoids. Moreover, longevity of adult parasitoids were highly decreased.

Greenhouse Whitefly Control on Marigolds, Michigan, 1991

Abstract Marigold plants were raised from seed in 6" clay pots for ten wk (10-12" tall) in a research greenhouse infested with whitefly at Michigan State University. The plants were watered by a drip irrigation system for 2 min/d, 4 d/wk (Sun, Mon, Wed, and Fri). Each treatment was replicated 6 times, except the control which was replicated 5 times. Precounts of 6 leaves per plant were completed on 3 May. The leaves were sampled randomly from each plant (3 leaves from the top half and 3 leaves from the bottom half of the plant). Whitefly larvae and pupae on the undersides of leaves were counted within a 38 mm2 area on each of 24 leaflets per plant. Therefore, an area of 30 cm2 per plant was observed. Insecticides were applied with an R&D CO2 sprayer with a single 8003 nozzle at 50 psi until runoff. Applications were applied 3 May, 10 May, and 17 May. Postcounts were made in the same manner as precounts on 24 May except whitefly pupae parasitized by Encarsia formosa were also counted. The no. of whiteflies reported for all sample dates is the total no. of whitefly larvae and pupae counted on leaf samples.

Mating and Oviposition of Three Encarsia Species (Hymenoptera : Aphelinidae) on the Greenhouse Whitefly, Trialeurodes vaporariorum (WESTWOOD) (Homoptera : Aleyrodidae)

To select a promising agent for biological control of the greenhouse whitefly, Trialeurodes vaporariorum (WESTWOOD), mating and oviposition behaviors of two native species, Encarsia sp. (A) and Encarsia sp. (B), and an introduced one, Encarsia formosa GAHAN, were observed. Mating behavior of Encarsia sp. (A) and Encarsia sp. (B) differed from that of E. formosa : the male of the former two species mounted the female before and after copulation, while the male of the latter did not. Encarsia sp. (A) and Encarsia sp. (B), which are arrhenotokous, laid fertilized female-producing eggs in healthy whiteflies, and unfertilized male-producing eggs on fully-grown larvae or pupae of E. formosa in whitefly pupae. The thelytokous parasitoid E. formosa laid all its eggs in unparasitized whiteflies, but the mechanism of its male occurrence is not clear. Fecundities of Encarsia sp. (A) and E. formosa were similar to each other and higher than that of Encarsia sp. (B).

Bionomics of the Whitefly-Parasite Complex Associated with Cotton in Southern California (Homoptera: Aleurodidae; Hymenoptera: Aphelinidae)

Bionomics of the Whitefly-Parasite Complex Associated with Cotton in Southern California (Homoptera: Aleurodidae; Hymenoptera: Aphelinidae)

Biological Studies on Encarsia formosa (Hymenoptera: Aphelinidae)1

Encarsia formosa Gahan, a parasite of worldwide occurrence, is an effective enemy of the greenhouse whitefly, Trialcurodes vaporariorum (Westwood), at temperatures of 24°C and higher. It shows a preference for whiteflies on nonpubescent leaves. If no hosts were previously available, Encarsia adults fed readily on whitefly pupae when confined with them. Host-feeding by this parasite has not been reported previously. E. formosa is uniparental, though bisexual. Males occur rarely and, as with other Encarsia species, they develop hyperparasitically as parasites of Encarsia larvae. No explanation of their appearance has been previously suggested. In the present work, the whiteflies in which males developed always contained Encarsia larvae, while those in which female-producing eggs were deposited were always unparasitized at the time of oviposition. The male-producing, hyperparasitic habit of E. formosa females appears to materialize only if they are unable to find unparasitized hosts; therefore, adult males usually occur only if the parasite-host ratio is high.