Use of an electrostatic sprayer for control of anopheline mosquitoes

The Electrodyn sprayer was compared with a compression sprayer (Hudson X-pert) for residual application of cypermethrin, a pyrethroid insecticide, to control the malaria vectors Anopheles arabiensis Patton and An. funestus Giles in experimental huts at Magugu in Tanzania. The time taken for hut spraying, 2-2.5 min per hut, was similar for both types of sprayer. Two or three huts were treated internally with cypermethrin at 40 or 80 mg a.i./m2 using Electrodyn formulation for comparison with 80 mg a.i./m2 using wettable powder formulation. Each of the twelve huts (including five untreated controls) was fitted with window exit traps and either louvre or verandah traps for mosquito sampling. The Electrodyn sprayer was fitted with a pair of elbowed deflectrodes to direct the positively charged spray droplets onto walls and ceiling. All treatments gave 94-100% mortality-rates of indoor-resting anophelines throughout the evaluation period of 11 weeks post-spray. Reductions of An.arabiensis and An.funestus females by 10-42% and 62-91%, respectively, in rooms and by 72% and 51% in exit traps indicated that cypermethrin deterred mosquitoes from entering the huts. Overall mortality-rates of mosquitoes were 66% of both species in huts treated with 40 mg/m2 Electrodyn, 43% An.funestus and 71% An.arabiensis due to 80 mg/m2 Electrodyn formulation and 49% An.funestus and 64% An.arabiensis due to 80 mg/m2 WP formulation (no significant differences). It is concluded that the Electrodyn sprayer with deflectrodes is a convenient and effective means of residual house-spraying with pyrethroid insecticide for malaria vector control.     

Discriminative feeding behaviour of Anopheles gambiae s.s. on endemic plants in western Kenya

Anopheles gambiae Giles s.s. (Diptera: Culicidae) is known to feed on plant sugars, but this is the first experimental study to consider whether it discriminates between plant species. Thirteen perennial plant species were selected on the basis of their local availability within the vicinity of human dwellings and larval habitats of An. gambiae s.s. in western Kenya. Groups of 100 or 200 mosquitoes were released into cages either with a cutting of one plant type at a time (single-plant assay) or with cuttings of all 13 plants simultaneously (choice assay), respectively, and left overnight. In the choice assay, direct observations of the percentages of mosquitoes perching or feeding on each plant were recorded over four 1-h periods each night. For both types of assay, mosquitoes were recaptured and the percentage that had fed on plants was assessed by testing them individually for the presence of fructose. To identify which plants the choice-assay mosquitoes had fed on, gas chromatography (GC) profiles of samples of mosquito homogenates were compared with GC profiles of extracts from relevant parts of each plant. Four of the plants that were observed to have been fed on most frequently in the choice assay (Parthenium hysterophorus L., Tecoma stans L., Ricinus communis L., and Senna didymobotrya Fresen) were also shown to have been ingested most often by mosquitoes in both types of assay, suggesting that An. gambiae is differentially responsive to this range of plants, regardless of whether the plants were presented singly or mixed together. Significantly more females than males fed on plants, with the exception of P. hysterophorus L., one of the plants most frequently fed on. For most plant species (ten of 13), GC profiles indicated that An. gambiae obtained sugars primarily from flowers. The exceptions were P. hysterophorus L., Lantana camara L. and R. communis L., on which An. gambiae fed more often from leaves and stems than from flowers.     

Studies of Spray Application of Microbial Herbicides in Relation to Conidial Propagule Content of Spray Droplets and Retention on Target

This paper addresses the hypothesis that the spray application system used will affect the retention of spray deposits of microbial herbicides on different plant structures. There was greater spray retention on the hypocotyl of 4 to 6-true leaf Amaranthus retroflexus plants (20-31%) sprayed with an aerosol-producing laboratory sprayer than with a hydraulic nozzle (3-5%). Spray deposition and retention from the hydraulic nozzle was increased by 28-42% when the nozzle was used horizontally. Spray droplets generally contained the expected conidial number for the conidial concentration but this was affected by increased inoculum density (size, concentration and mycelial contamination), causing a reduction in the actual number of conidia present, compared to the expected. Up to 40-50% of the conidia in the sprayed suspension could not be accounted for when conidium deposition was on a target. This loss could increase to 90-92% when the weed was sprayed under a crop canopy.     

Optimisation of sequence and orientation for used nozzles based on few, full boom distribution measurements

Most studies on uniformity of pesticide applications beneath agricultural spraying booms are based on the characteristics of nozzle spray patterns. When optimising general features (boom height, pressure, ...), average nozzle characteristics are used. In this research, individual nozzle characteristics are essential. When utilising slightly used nozzles, small irregularities in the nozzle spray distribution may be averaged out or amplified in the resulting full-boom distribution. A method is proposed to find whether the coefficient of variation (cv) of a field sprayer spray distribution could be optimised by altering the sequence and orientation of a given set of flat fan nozzles. A manageable model is used in order to quickly compute possible full-boom distributions (and cv's) with a given set of single nozzle spray distributions. The individual nozzle spray distributions are extracted from a limited series of full-boom spray distribution measurements (three in most cases) with randomised nozzle sequence and orientation by means of a Matlab optimisation algorithm.     

Defined medium supporting development of cleansed Plasmodium berghei ookinetes in Anopheles stephensi.

Hamsters blood infected with Plasmodium berghei was cultured in vitro for the development of ookinetes. The ookinetes were separated from blood components, suspended in various defined media and fed to Anopheles stephensi through a membrane. The development of the oocysts and infective sporozoites was recorded. Mosquitoes infected with ookinetes suspended in L15 formulated into L15-B, L15-D (a medium specially modified for this purpose), IPL-41 or 199 media with no proteins added, developed at least as many oocysts as the control mosquitoes fed ookinetes suspended in blood. Ookinetes suspended in the L15-B medium yielded more oocysts than after feeding ookinetes suspended in L15-B with 5% casein. Sporozoites from mosquitoes maintained on blood, L15-B, L15-D, or L15-B with 5% casein were shown to be infective to hamsters. Mosquitoes fed ookinetes suspended in sucrose solutions showed very few oocysts, but the yield was increased when a blood meal was given 2-4 days after the infective meal. Some of the oocysts which had developed from the ookinetes suspended in artificial media were found to have degenerated. The described system could be potentially useful for a study of the interaction between the vector physiology and the parasite. The possible use of the system to learn which media should be developed in the future for in vitro cultivation of oocysts is discussed.     

Brugia malayi and Brugia pahangi: transmission blocking activity of ivermectin and brugian filarial infections in Aedes aegypti

Brugia malayi- or Brugia pahangi-infected, microfilaremic jirds (Meriones unguiculatus) were treated with ivermectin at a single dose of 200 micrograms/kg body weight, administered subcutaneously. After different time intervals, Aedes aegypti mosquitoes were fed on treated or untreated jirds. Sausage stage, L2, and L3 larvae failed to develop in mosquitoes that fed on jirds from 15 to 30 days post-treatment. After 1 month, the numbers of L3 larvae recovered from mosquitoes fed on treated B. pahangi jirds were comparable to controls. However, the number of L3's recovered from mosquitoes fed on B. malayi jirds remained significantly lower than controls, 2 and 3 months after treatment. This reduction suggests that ivermectin may be more effective in blocking transmission of B. malayi than B. pahangi. Ivermectin treatment had no effect on the mean number of circulating microfilariae in treated jirds. Therefore, mosquitoes ingested comparable numbers of microfilariae when compared to those mosquitoes fed on untreated controls. Only in the case of jirds infected with B. malayi did the circulating microfilarial counts fall 30 days after treatment. The failure of microfilariae to develop to the L3 stage in mosquitoes fed on jirds within 30 days of treatment was not due to failure of mosquitoes to ingest microfilariae. Brugia malayi microfilariae also failed to develop to L3 in mosquitoes that were allowed to feed on microfilaremic jird blood treated with ivermectin (50 ng/ml) in vitro, indicating its efficacy at low concentrations. In addition to N-acetyl glucosamine, microfilariae obtained for a period of 15 days from ivermectin-treated but not control jirds showed D-mannose, N-acetyl galactosamine, and L-fucose moieties on the surface of the sheath.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of repellents Ocimum forskolei and deet on the response of Anopheles stephensi to host odours

The behavioural response of Anopheles stephensi Liston (Diptera: Culicidae) to incubated host odours (from human and goat) and to human odour in combination with a repellent plant, Ocimum forskolei (Labiatae), or deet (N, N, diethyl-toluamide) (20%) was tested in a dual-port olfactometer. An. stephensi was significantly attracted to both host odours compared with air alone, but showed no preference when given a choice between both host odours simultaneously. In choice tests, the addition of deet to human odour did not significantly divert mosquitoes to human odour alone, but did divert them to goat odour. O. forskolei combined with human odour diverted mosquitoes to goat or human odour alone. Combinations of human odour and O. forskolei, and human odour and deet were both as unattractive as air alone, and attracted mosquitoes equally when offered simultaneously. The results indicate that use of O. forskolei as a repellent would be beneficial in reducing vector biting if used in communities in areas with partially zoophilic mosquito species such as An. stephensi, and where animals are present.     

Optimizing the application of entomopathogenic nematodes: experimental set-up

The complex issue concerning the spray application of Entomopathogenic Nematodes (EPNs) with a hydraulic sprayer is still not solved. This research project focuses on the effect of spray application technique on the viability and deposition of EPNs. In this paper the experimental set-up used for this evaluation is described. A modular spray application system has been developed and is currently used to evaluate the effect of different parts of a sprayer on the viability of the EPNs. Based on the results of experiments using this modular spray application system, recommendations regarding pump type, mixing system, nozzle type and filter size will be formulated. Because of the large number of experiments in this research project, an image analysis system for the determination of the viability of the nematodes is developed. This paper describes two experiments comparing the new developed image processing technique with the standard microscopic counting technique.     

喷雾方式及喷液量对吡蚜酮和啶虫脒在棉田的沉积分布及棉蚜防治效果的影响

为探明防治棉田棉蚜Aphis gossypii (Glover)的最佳喷雾方式及喷液量, 提高棉田的农药利用率, 作者于2011-2012年在山东省棉花苗期和成株期分别使用背负式手动喷雾器和背负式机动弥雾机以常规大容量和低容量喷雾, 比较杀虫剂25%吡蚜酮可湿性粉剂和3%啶虫脒乳油的喷雾雾滴在棉花田的沉积分布及棉蚜防治效果。结果表明： 在棉花苗期, 3%啶虫脒乳油用量450 mL/ha时, 使用机动弥雾机以75, 150和225 L/ha喷液量喷雾, 药剂在地面的流失率分别为24.4%, 28.9%和26.7%; 使用手动喷雾器以300, 450和600 L/ha喷液量喷雾, 杀虫剂在地面的流失率分别为35.6%, 37.8%和46.7%; 啶虫脒不同喷雾处理对棉蚜的防效无显著性差异（P>0.05）。在棉花成株期, 25%吡蚜酮可湿性粉剂用量为300 g/ha时, 使用手动喷雾器以600 L/ha喷液量喷雾, 药剂地面流失率为13.3%; 使用机动弥雾机以喷液量150 L/ha喷雾时, 药剂地面流失率为3.3%; 25%吡蚜酮可湿性粉剂用量减少至225 g/ha, 使用机动弥雾机以喷液量150和300 L/ha喷雾, 对棉蚜的防效与吡蚜酮用量300 g/ha、 使用手动喷雾器在喷液量600 L/ha条件下喷雾相比没有显著差异（P>0.05）。使用机动弥雾机喷雾可以减少田间用药量和喷液量, 降低药液的流失率, 减轻对环境的污染。     

Population genetics of Plasmodium resistance genes in Anopheles gambiae: no evidence for strong selection

Anopheles mosquitoes are the primary vectors for malaria in Africa, transmitting the disease to more than 100 million people annually. Recent functional studies have revealed mosquito genes that are crucial for Plasmodium development, but there is presently little understanding of which genes mediate vector competence in the wild, or evolve in response to parasite-mediated selection. Here, we use population genetic approaches to study the strength and mode of natural selection on a suite of mosquito immune system genes, CTL4, CTLMA2, LRIM1, and APL2 (LRRD7), which have been shown to affect Plasmodium development in functional studies. We sampled these genes from two African populations of An. gambiae s.s., along with several closely related species, and conclude that there is no evidence for either strong directional or balancing selection on these genes. We highlight a number of challenges that need to be met in order to apply population genetic tests for selection in Anopheles mosquitoes; in particular the dearth of suitable outgroup species and the potential difficulties that arise when working within a closely-related species complex.     

Quantitative method for pheromone delivery in studies of sensory adaptation of moth antennae

Abstract.  A pheromone sprayer and an electroantennogram (EAG) are used to study sensory adaptation in the antennae of male obliquebanded leafrollers, Choristoneura rosaceana and oriental fruit moths, Grapholita molesta , to the main pheromone compounds ( Z )-11-tetradecen-1-yl acetate ( Z 11-14:Ac) and ( Z )-8-dodecen-1-yl acetate ( Z 8-12:Ac), respectively. The atomization of 0.125, 0.25, 0.5 or 1 μL ethanol min⁻¹ into the EAG air delivery tube at an airflow rate of 2 L min⁻¹, with resultant concentrations of 6.25, 12.5, 25 or 50 × 10⁻⁵μL ethanol mL air⁻¹, respectively, does not affect the EAG response of C. rosaceana or C. molesta after a 30-min exposure period. The atomization of 0.125 μL min⁻¹ of a solution of 8 mg Z 11-14:Ac mL⁻¹ ethanol into the EAG air delivery tube at an airflow rate of 2 L min⁻¹, with a resultant concentration of 0.5 ng pheromone mL⁻¹ air, reduces the EAG response of C. rosaceana by approximately 70% after a 15-min exposure period. An additional 15 min of exposure to pheromone does not result in increased sensory adaptation. Antennae recover 32% of the lost responsiveness when exposed to pheromone-free air for 15 min. The atomization of 0.125 μL min⁻¹ of a solution of 8 mg Z 8-12:Ac mL⁻¹ ethanol into the EAG air delivery tube at an airflow rate of 2 L min⁻¹, with a resultant concentration of 0.5 ng pheromone mL⁻¹ air, reduces the EAG response of C. molesta antenna by approximately 80% after a 15- or 30-min exposure period. The antennae of this species do not recover responsiveness when exposed to pheromone-free air for 15 min.     

Particulate Matter on Foliage of 13 Woody Species: Deposition on Surfaces and Phytostabilisation in Waxes – a 3-Year Study

Particulate matter (PM) as an air pollutant can be harmful for human health through allergic, mutagenic and carcinogenic effects. Although the main focus is on decreasing air pollution, after PM has been emitted to the atmosphere, one of the realistic options to decrease it's concentrations in urbanized area will be phytoremediation. This study compared the capacity to capture PM from air of seven tree species commonly cultivated in Poland (Catalpa bignonioides Walter, Corylus colurna L., Fraxinus pennsylvanica Marsh., Ginkgo biloba L., Platanus × hispanica Mill. ex Muenchh., Quercus rubra L., Tilia tomentosa Moench ‘Brabant’) and six shrub species (Acer tataricum subsp. ginnala (Maxim.) Wesm., Sambucus nigra L., Sorbaria sorbifolia (L.) A.Br., Spiraea japonica L.f., Syringa meyeri C.K. Schneid. ‘Palibin’, Viburnum lantana L.). Significant differences were found between species in mass of total PM accumulation for two PM categories and three size fractions determined and in amount of waxes. A positive correlation was found between in-wax PM of diameter 2.5–10 μm and amount of waxes, but not between amount of waxes and amount of total PM or of any size fraction.     

Effect of spray application technology on the biological control of aphids in Brussels sprouts

A field trial was carried out to evaluate different application techniques for crop penetration and biological efficacy of aphid control in Brussels sprouts. Six different application techniques were tested at a pressure of 4.0 bar in a field trial in 3 parallels at the Provincial Vegetable Research Centre in Kruishoutem (PCG): a standard ISO 02 flat fan nozzle (at 200 l/ha), an ISO 04 twin air inclusion nozzle (at 800 l/ha), an ISO 03 drift reducing nozzle, an air injection nozzle (Airjet,) droplegs in combination with an ISO 03 drift reducing nozzle and an ISO 03 air inclusion nozzle (all at 400 l/ha). Best biological control of the aphids and spray distribution was found for the twin air inclusion nozzle, the air inclusion nozzle and the airjet-system. These are all drift reducing techniques because of their coarse droplet size spectrum or the effect of air support which makes the droplets faster. Both effects improve crop penetration. No added value was found for the droplegs for this type of spray treatments. Fine droplets, produced by a standard flat fan, did not give good results on biological control or penetration into the crop.     

Effect of humidity on cuticular water permeability of isolated cuticular membranes and leaf disks

The effects of humidity on water permeability of astomatous, isolated cuticular membranes and leaf disks of Citrus aurantium L., Vinca major L., Prunus laurocerasus L., Hedera helix L. and Forsythia intermedia (Thunb.) Vahl. were investigated by a new method using 3H2O. With isolated cuticular membranes of P. laurocerasus the isotope method resulted in values similar to those obtained by a well-established gravimetric method. Cuticular water permeability significantly increased by factors of 2 to 3 when air humidities increased from 2 to 100%. Plots of permeances vs. air humidity were non-linear and the slope increased with increasing air humidity. Permeances of intact leaf disks showed a response to increasing humidity similar to those of isolated cuticular membranes. When cuticular water permeability was measured using wax-free, isolated polymer matrix membranes that had been methylated, the effect of air humidity was significantly suppressed compared to non-methylated polymer matrix membranes. From this observation it is concluded that non-esterified, free carboxyl groups present in the cutin polymer matrix significantly contribute to the effect of humidity on cuticular water permeability. These and other polar groups sorb water, which in turn increases the water permeability of polar domains of the cuticle. This humidity-sensitive, polar path of cuticular water permeability is arranged in parallel with the major, dominating and humidity-independent, non-polar path of cuticular water permeability formed by the lipophilic wax components of the cuticle. This conclusion is supported by the fact that cuticular transpiration can be increased by orders of magnitude upon (i) wax extraction, (ii) increase in temperature or (iii) the action of plasticizers, none of which influenced or only marginally influenced the permeability of inorganic ions penetrating plant cuticles across humidity-sensitive polar pores.     

Comparing oxalic acid and sucrocide treatments for Varroa destructor (Acari: Varroidae) control under desert conditions

The effectiveness of oxalic acid (OA) and Sucrocide (S) (AVA Chemical Ventures, L.L.C., Portsmouth, NH) in reducing populations of the varroa mite Varroa destructor Anderson & Trueman (Acari: Varroidae) in honey bee, Apis mellifera L. (Hymenoptera: Apidae) colonies was measured under the desert conditions of Arizona, USA. OA and S were applied three times 7 d apart. A 3.2% solution of OA was applied in sugar syrup via a large volume syringe, trickling 5 ml per space between frames in the colony. S was applied at a concentration of 0.625% (mixed with water), according to the label directions, using a compressed air Chapin sprayer at 20 psi to apply 59 ml per frame space. Varroa mites, collected on a sticky board before, during, and after the treatments, were counted to assess the effectiveness of the treatments. This study showed that a desert climate zone did not confer any positive or negative results on the acaricidal properties of OA. Even with brood present in colonies, significant varroa mite mortality occurred in the OA colonies. In contrast, we found that Sucrocide was not effective as a mite control technique. Despite its ability to increase mite mortality in the short-term, varroa mite populations measured posttreatment were not affected any more by Sucrocide than by no treatment at all.     

Influence of nutritional and physiological status on behavioral responses of Aedes aegypti (Diptera: Culicidae) to deltamethrin and cypermethrin.

Excito-repellency responses of Aedes aegypti (L.) exposed to deltamethrin and cypermethrin were assessed using an excito-repellency test system. Contact irritancy and non-contact repellency assays compared non-bloodfed (unfed) parous (post-gravid), nulliparous, early blood-fed, late blood-fed, sugar-fed, and unmated female mosquitoes for behavioral responses based on nutritional and physiological conditions at the time of testing. Rates of escape during contact exposure with either compound were most pronounced in parous mosquitoes, followed by unmated mosquitoes, when compared to other conditional states. Significantly higher numbers of parous females also escaped from control chambers compared to other cohorts (P <0.05). Irritability of blood- and sugar-fed mosquitoes was noticeably suppressed. We conclude that nutritional and physiological conditions (including age) of mosquitoes at the time of testing can significantly influence behavioral responses (excito-repellency) to insecticides. The findings indicate that whether due to chronological age, nutrition, physiological state, or innate (circadian) activity patterns, careful consideration must be given to the selection of appropriate conditioned mosquitoes for testing.     

Micro sprayers for the laboratory application of pesticides

The microtip nozzle assembly described by Uk (1978) has been modified to provide a reliable and versatile sprayer for the laboratory application of pesticide formulations. The improved performance has been achieved through the introduction of knurled thimbles giving controlled adjustment of needle and stylus settings and by the provision of an offset liquid reservoir (0·1–2 ml) either pressurised or non-pressurised. The device, which delivers monosize droplets (in-flight diameter 50–500 μm) at velocities ranging from 0·5–20 m s^-1 has been used for aqueous and oil solutions, water dispersible powders and emulsifiable concentrates of varying concentration (0·1-30g a.i. litre^-1) and is particularly suitable for the application of radiolabeled chemicals.     

A floral‐derived attractant for Aedes aegypti mosquitoes

The reproductive success of Aedes aegypti (L.) (Diptera: Culicidae) is strongly dependent on the availability of carbohydrates in the environment and the ability of the mosquitoes to locate them. The most significant source of carbohydrates for mosquitoes is nectar from flowering plants, which mosquitoes locate by their volatile compounds. The aim of our work was to identify plant volatile compounds that elicit a behavioral response in Ae. aegypti, which may be included in a mosquito trap for surveillance and/or control purposes. Landing‐preference bioassays were performed with plants of three species—Plectranthus neochilus Schltr. (Lamiaceae), Tagetes patula L. (Asteraceae), and Lobularia maritima (L.) Desv. (Brassicaceae)—as lures and toxic sugar baits as landing markers. Mosquitoes landed only on L. maritima. Freshly cut inflorescences of L. maritima elicited a positive flight response in both sexes of mosquitoes. The analysis of the compounds in the static head space of L. maritima was performed by solid phase microextraction (SPME). Of the single volatile compounds tested, acetophenone was attractive and 1‐octanol caused a flight aversive response. These findings are relevant as there are no reported plant‐derived compounds attractive to A. aegypti. As both the male and female mosquitoes sugar feed, traps baited with plant odors are able to lure the whole adult population, making it an interesting option for including in future mosquito surveillance traps.     

The influence of the brain hormone on retention of blood in the mid-gut of the mosquito Aedes aegypti (L.). III. The involvement of the ovaries and ecdysone.

Most female mosquitoes require a blood-meal in order to produce mature o?cytes. An egg development neurosecretory hormone (EDNH), which is produced in the medial neurosecretory cells (m.n.c.) of the brain and stored in the corpus cardiacum, is released into the haemolymph following the ingestion of blood and is essential for the promotion of ovarian development to maturity. It has been shown that a factor from the m.n.c., presumably EDNH, is necessary if the blood-meal is to be retained in the mid-gut until the o?cytes approach maturity. The present paper shows that retention is not a direct result of the action of EDNH, but is dependent on the ovaries and may well involve ecdysone. Removal of the ovaries before a blood-meal leads to early haem-defaecation, but delay can be restored by injection of ecdysterone. Sub-threshold feeders and mosquitoes decapitated immediately after the intake of blood, each of which would be expected to eliminate the blood-meal early, also show a delay in the onset of haem-defaecation when injected with ecdysterone. Further, both in ovariectomized insects and sub-threshold feeders the time of onset of haem-defaecation is associated with the dose of ecdysterone given.     

Bee venom phospholipase inhibits malaria parasite development in transgenic mosquitoes

Malaria kills millions of people every year, and new control measures are urgently needed. The recent demonstration that (effector) genes can be introduced into the mosquito germ line to diminish their ability to transmit the malaria parasite offers new hope toward the fight of the disease (Ito, J., Ghosh, A., Moreira, L. A., Wimmer, E. A. & Jacobs-Lorena, M. (2002) Nature, 417, 452-455). Because of the high selection pressure that an effector gene imposes on the parasite population, development of resistant strains is likely to occur. In search of additional antiparasitic effector genes, we have generated transgenic Anopheles stephensi mosquitoes that express the bee venom phospholipase A2 (PLA2) gene from the gut-specific and blood-inducible Anopheles gambiae carboxypeptidase (AgCP) promoter. Northern blot analysis indicated that the PLA2 mRNA is specifically expressed in the guts of transgenic mosquitoes with peak expression at approximately 4 h after blood ingestion. Western blot and immunofluorescence analyses detected PLA2 protein in the midgut epithelia of transgenic mosquitoes from 8 to 24 h after a blood meal. Importantly, transgene expression reduced Plasmodium berghei oocyst formation by 87% on average and greatly impaired transmission of the parasite to naive mice. The results indicate that PLA2 may be used as an additional effector gene to block the development of the malaria parasite in mosquitoes.