Factors influencing adult female oviposition in the citrus leafminer Phyllocnistis citrella

1 The citrus leafminer (CLM) Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is a serious pest in most citrus‐growing regions of the world. The influence of leaf length, citrus species or variety, leaf colour tone and temperature on CLM oviposition was studied from field observations and laboratory experiments. The spatial distribution of eggs on leaves was also examined. Field data were obtained from 1100 samples collected in eastern Spain for 7 years. 2 Significant differences in oviposition rate were found among citrus species in ‘no choice’ laboratory experiments. This tendency was not apparent in the field due to the confounding effect of such factors as the intensity of new flushes and adult CLM abundance. Leaf colour tone and air temperature in the range studied (18–27°C) had no effect on CLM egg‐laying. 3 The distribution of eggs among leaves was random for population densities lower than four eggs per leaf, but became strongly aggregated above this, when not all eggs could survive and complete development. 4 The CLM developmental stage found on leaves depended on the leaf length, and most of the egg‐laying occurred only on leaves that were 10–25 mm long. These leaves had the highest CLM stages in the field and thus give the best estimate of CLM oviposition.     

Preference and performance of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) on three citrus hosts: laboratory and field assessment

The relationship between preference and performance is crucial to the ecology and evolution of plant-insect interactions. Oviposition preference and offspring performance were evaluated for a citrus pest, the leafminer Phyllocnistis citrella (Lepidoptera: Gracillariidae), on three of its host plants: lemon (Citrus limon L. Burm.), orange (Citrus sinensis L. Osbeck), and grapefruit (Citrus paradisi Macfadyen) in Tucumán province (northwest Argentina). Choice and no-choice tests were performed in open and enclosed environments, and performance parameters (development time, survival, pupal size, and sex ratio) were estimated from laboratory rearing and 3-yr field sampling data. Parasitism rates were studied in laboratory choice test and field assessments. Preference trends were inconsistent, with lemon receiving more eggs in some tests, whereas no preference was observed in others. Patterns of host use in the field did not show significant differences among species. Leafminer performance, including parasitism and predation rates, was generally homogeneous among host plants. From these results, lemon, orange, and grapefruit seem to represent intrinsically similar resources for P. citrella populations in northwest Argentina, a trend that was accompanied by a lack of consistent oviposition preferences in foraging females. Ecological conditions might be more important than physiological adaptation in shaping a probably labile host ranking in this pest species.     

Structure and composition of the assemblage of parasitoids associated to Phyllocnistis citrella Pupae Stainton (Lepidoptera: Gracillariidae) in citrus orchards in Southern Brazil

The structure and composition of the assemblage of pupal parasitoids of Phyllocnistis citrella Stainton, the citrus leafminer, were studied in two citrus orchards (Citrus deliciosa Tenore cv. Montenegrina and Citrus sinensis (L.) Osbeck x Citrus reticulata Blanco hybrid Murcott), in Montenegro County (29 degrees 68'S and 51 degrees 46'W), southern Brazil. At fortnightly samplings, from July 2001 to June 2003, all the new shoots from 24 randomly selected trees were inspected. The species richness reached five native species in the Murcott orchard, and six in Montenegrina. In Murcott, the presence of Ageniaspis citricola (Hymenoptera: Encyrtidae), an exotic species, was detected in the first year of sampling, probably migrating from the nearby areas where it had been released for the miner control. In Montenegrina, its presence was only registered in the second year. A. citricola in both areas was dominant and changed the community structure of parasitoid complex of P. citrella in both orchards.     

Differences in water relations among the citrus leafminer and two different populations of its parasitoid inhabiting the same apparent microhabitat

The water balance relationships of adult females and pupae of two populations (Australian and Taiwan) of the parasitic wasp Ageniaspis citricola, a biological control agent of the citrus leafminer Phyllocnistis citrella, were compared to determine whether habitat preferences might differ between them. No differences were detected between Australian and Taiwan strains of the wasp during the pupal stage, but adult females from the Australian strain had lower net water loss rates than the parasitoid adults from Taiwan. This implies a greater moisture requirement by adults of the Taiwan strain, which should be considered before they are released into a new environment in classical biological control programs.     

Field evaluation of integrated pest management-compatible pesticides for the citrus leafminer Phyllocnistis citrella (Lepidoptera: Gracillariidae) and its parasitoid Ageniaspis citricola (Hymenoptera: Encyrtidae)

Potentially selective and integrated pest management (IPM)-compatible pesticides for the citrus leafminer Phyllocnistis citrella Stainton and its parasitoid Ageniaspis citricola Logvinovskaya were compared under nursery field conditions at Gainesville, FL. In 1996, replicated blocks of young grapefruit trees were treated with 2% petroleum oil and 1 x the lowest recommended field rate (LRFR) of diflubenzuron + oil (0.4%). Untreated and treated controls (avermectin at 1 x the LRFR + oil) were included. In 1997, blocks were treated with oil (3%), 1 x the LRFR of azadirachtin + oil, 1 x the LRFR of diflubenzuron + oil and 0.1 x the LRFR of avermectin + oil. Untreated and treated controls were again included. Oil at 3%, azadirachtin at 1 x the LRFR + 0.4% of oil, and diflubenzuron at 1 x the LRFR + 0.4% of oil were shown to be IPM-compatible pesticides. In 1997, these blocks had fewer mines per leaf and P. citrella pupae parasitized by A. citricola per total leaves sampled compared with the untreated control but more than the treated control (alpha = 0.05). Avermectin at 0.1 x the LRFR + 0.4% of oil was not considered an IPM-compatible pesticide because, while it reduced the number of P. citrella mines per leaf, it reduced the number of A. citricola to levels as low as the treated control. Actual P. citrella infestation levels had no detectable effect on tree growth and vigor. Pesticide applications were not justified when P. citrella infestations were < 1 mine per leaf and the biological control agent A. citricola was present.     

Interactions between the red imported fire ant, the citrus leafminer, and its parasitoid Ageniaspis citricola (Hymenoptera: Encyrtidae): Laboratory and field evaluations

Interactions between the red imported fire ant [Solenopsis invicta (Hymenoptera: Formicidae)], the citrus leafminer [Phyllocnistis citrella (Lepidoptera: Gracillariidae)], and the citrus leafminer endoparasitoid Ageniaspis citricola (Hymenoptera: Encyrtidae) were investigated under laboratory and field conditions in Florida. Previous studies had shown that S. invicta would selectively prey on brown citrus aphids (Toxoptera citricida) parasitized by Lipolexis oregmae and Asian citrus psyllids (Diaphorina citri) parasitized by Tamarixia radiata, which led us to question whether S. invicta would selectively prey on citrus leafminer (CLM) larvae or eggs parasitized by A. citricola. In the laboratory trial, there was no significant difference between the type of CLM larvae preyed on. However, higher predation was observed on parasitized CLM larvae reared on potted plants in a citrus grove. A subsequent citrus grove test revealed slightly, although not significantly, lower levels of parasitism by A. citricola in trees to which ants had access because predation by ants was higher. However, predation by other predators in the trees to which ants had no access resulted in no significant differences in CLM densities in the two treatments. The field data provide, for the first time, the seasonal phenology of the CLM and its parasitoid A. citricola in the Indian River region of Florida in an unsprayed grapefruit block.     

Impact of Phyllocnistis citrella (Lepidoptera: Gracillariidae) on leaf area development and yield of mature citrus trees in the Mediterranean area

Seasonal population trends and damage to citrus trees by the leafminer Phyllocnistis citrella Stainton were studied in the Valencia area of eastern Spain from 1996 to 1999. The area-wide seasonal flushing pattern of citrus trees and leafminer population trends were determined in 10 mature citrus orchards. In the 10 orchards, the annual percentage of new shoots that developed in the spring ranged from 51 to 96% for individual orchards (mean of 80%). Phyllocnistis citrella populations damaged new leaves from July to November. During this period, approximately 45% of the new leaf area was lost due to leafminer mining. In addition, at three mature citrus orchards, two 'Navelina' sweet oranges from 1996 to 1999 and one 'Clementine' mandarin (variety 'Clemenules') in 1998 and 1999, the leaf area damage, spring flushing pattern, and crop yield were determined in trees sprayed one to three times a year with abamectin (Epimeck, 0.02%) to control P. citrella and compared with nonsprayed control trees. In these three orchards, damaged leaf area in summer-fall flushes was on average 52% in nonsprayed and 8% in sprayed trees. No significant differences were found between sprayed and nonsprayed trees in the spring flushing and flowering pattern, number of fruits or fruit diameter. In Mediterranean areas, P. citrella damaged only 5-15% of the annual new leaf area of mature trees and yield was usually not affected by the pest.     

Indigenous parasitoids (Hym., Chalcidoidea) of Phyllocnistis citrella Stainton (Lep., Gracillariidae) in Jaguariúna, São Paulo State, Brazil: preliminary results

Abstract: The citrus leafminer, Phyllocnistis citrella Stainton, is native to Asia and was detected for the first time in Brazil in 1996. The objectives of this study were to conduct a survey of parasitoids attacking citrus leafminer in Jaguariúna, one of the citrus production regions of São Paulo State, Brazil, and to determine whether indigenous species were providing effective control of this pest species. The collections of new leaves were made weekly at citrus groves in Jaguariúna from October 1996 to October 1997. Of the six indigenous parasitoids which were found, Galeopsomyia fausta LaSalle was the most abundant parasitoid of P. citrella in this region, accounting for more than 90% of the specimens collected. Thus, this species is a serious candidate for biological control of the citrus leafminer in this region of Brazil. Other species collected were Horismenus sp., Cirrospilus 'sp. C', Elasmus sp., Eupelmus sp. and Conura (Ceratosmicra) sp. The mean percentage of parasitism was 39.28% (6.19−86.21%) in unsprayed orchards and 21.38% (1.33−56.63%) in orchards that were occasionally treated with fungicides, acaricides and insecticides Temik and Dipterex.     

Efficacy and uptake of soil-applied imidacloprid in the control of Asian citrus psyllid and a citrus leafminer, two foliar-feeding citrus pests

The systemic neonicotinoid insecticide imidacloprid, Admire Pro, was applied to 3- and 4-yr-old nonbearing 'Rio Red' grapefruit, Citrus x paradisi Macfad., trees in 2006 and 2007, respectively, to determine its effects in the control of two major citrus pests, the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), and a citrus leafminer Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae). Young flush shoots were randomly collected weekly for 13 and 11 wk in 2006 and 2007, respectively, to determine the infestation levels and densities of immature stages of both Asian citrus psyllid and P. citrella. Additional flush shoot samples were collected in 2007 and titers of imidacloprid in leaf tissue were determined using an enzyme-linked immunosorbent assay. Soil application of imidacloprid significantly reduced the infestation levels and densities of both pests on flush shoots, starting from the second week post application. The effects of the neonicotinoid insecticide were similar in both years. Analysis of imidacloprid concentration in leaf tissue showed a gradual increase during the first 3 wk, and titers remained well above 200 ppb for 11 wk postapplication. Significant positive correlations were obtained between imidacloprid titers in leaf tissue and the percentage of control levels achieved for both pests. A high level of suppression of both P. citrella and Asian citrus psyllid populations on citrus trees was associated with imidacloprid titer in leaf tissue >200 ppb, which was reached 2 wk after soil treatment. Although soil application of imidacloprid did not provide rapid knockdown of Asian citrus psyllid and P. citrella populations, it resulted in chronic residues in leaf tissue and long-term suppression of both pests.     

Survival and development of immature stages of the Mediterranean fruit fly (Diptera: Tephritidae) in citrus fruit

We studied, under laboratory conditions, the performance of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), immature stages in intact whole fruit of three sweet orange varieties, lemon, and bitter oranges. Both citrus variety and fruit part (flavedo, albedo, and pulp) had strong effects on larval performance, smaller effects on pupae, and no effects on eggs. Fruit peel was the most critical parameter for larval development and survival, drastically affecting larval survival (inducing very high mortality rates). Among fruit regions, survival of larvae placed in flavedo was zero for all varieties tested except for bitter orange (22.5% survival), whereas survival in albedo was very low (9.8-17.4%) for all varieties except for bitter orange (76%). Survival of pupae obtained from larvae placed in the above-mentioned fruit regions was high for all varieties tested (81.1-90.7%). Fruit pulp of all citrus fruit tested was favorable for larval development. The highest survival was observed on bitter oranges, but the shortest developmental times and heaviest pupae were obtained from orange cultivars. Pulp chemical properties, such as soluble solid contents, acidity, and pH had rather small effects on larval and pupal survival and developmental time (except for juice pH on larvae developmental duration), but they had significant effects on pupal weight.     

Effects of gamma radiation on the reproduction biology and mating competitiveness of citrus leafminer Phyllocnistis citrella Stainton

The citrus leafminer (CLM), Phyllocnistis citrella Stainton, is one of the most serious pests of Iran's citrus nursery stocks. In this study, the effects of gamma radiation at doses of 100–450?Gy on the biological and reproductive parameters of P. citrella were determined. The results showed that the mean percentage of pupal mortality increases with a rise in the dose. Also, the mean values of this parameter were higher for irradiated females, indicating higher sensitivity. The mean fertility of the irradiated females mated with normal males was affected drastically and reached zero at 300?Gy. The hatchability of the eggs laid by normal females mated with irradiated males dropped to 2% at the highest irradiation dose of 450?Gy. The results of this test showed that females have a higher radio-sensitivity than males. The competitiveness values fluctuated from 0.2 to 0.6 at doses higher than 200?Gy. The results showed that the male CLMs irradiated with sterilizing doses could compete suitably with the untreated males in laboratory conditions.     

Seasonal variation of immature stages of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in Citrus sinensis orchards under two management systems

Phyllocnistis citrella Stainton is considered an important pest of citrus, causing both direct (reduction on the photosynthetic area) and indirect damage (facilitation of invasion by bacteria that cause citrus canker). The lack of information about the population dynamics of P. citrella, considering the cultivation systems and varieties grown in citrus orchards in Rio Grande do Sul, Brazil, motivated this study. It aimed to evaluate the seasonal variation of immature stages of P. citrella, from June 2002 to July 2003, in two orchards of Citrus sinensis, cv. 'Valencia', one maintained according to organic management principles and the other under conventional ones. Fortnightly samplings were carried out, being one shoot collected from each one of 27 randomly chosen plants. The leaves were analyzed for the presence of eggs, larvae, pupae and mines of P. citrella. Leafminer was recorded from October 2002 to April 2003 in the organic orchard, and from November 2002 to July 2003 in the conventional one. A relationship between population size and resource availability (young leaves) was observed. However, population establishment does not depend exclusively on the existence of resources, but also on suitable climatic conditions. This was evidenced by the absence of attacks on the first shooting, which began in late winter. Meteorological factors and resource availability as a whole explain about 64% and 53% of the observed variation in the population size of P. citrella, respectively in the organic and conventional orchards.     

柑桔潜叶蛾对柑桔的为害及经济阈值的研究

调查福州市郊柑桔园柑桔潜叶蛾（Ｐｈｙｌｏｃｎｉｓｔｉｓｃｉｔｒｅｌａ）在雪柑、芦柑、蕉柑、福桔４个品种上的为害情况．根据其为害特性和柑桔果实产量大小年份可能给经济阈值带来的误差,采用同一树上以秋梢为计量单位,环割被测枝条（避免枝条间养分重新分配而带来误差）的方法,研究了为害秋梢的叶片光合作用强度,当年和翌年春夏梢的生长量,翌年果实品质和重量,以及叶片被害程度与柑桔潜叶蛾幼虫密度的关系．结果表明,柑桔受潜叶蛾为害后具有一定的光合补偿及组织愈伤的补偿能力;根据福州地区１９９４年柑桔生产力,以雪柑为品种确定经济阈值为１．２１头１龄幼虫／嫩叶;缩小了经济阈值受果实产量大小年份差异而带来的误差;同时考虑品种、柑桔园水热条件、产量水平、天敌作用等多种生态因子,建立了多因子经济阈值模型     

Population dynamics and functional response of Citrostichus phyllocnistoides (Narayanan) (Hym., Eulophidae) on citrus leaf-miner, Phyllocnistis citrella Stainton (Lep., Phyllocnistidae) in Fuzhou region of south-east China

Abstract:  Population dynamics of the citrus leaf-miner (CLM) Phyllocnistis citrella Stainton, and its major parasitoid Citrostichus phyllocnistoides (Narayanan) were investigated from June to September 1994 at the teaching and research farm of the Fujian Agricultural and Forestry University (FAFU), south-east China. Based on the field investigation, the functional and numerical responses of C. phyllocnistoides were studied in laboratory experiments. During the survey period, four peaks of CLM and C. phyllocnistoides populations were observed in the growing stage of summer shoots and two peaks of CLM and C. phyllocnistoides populations, respectively, in the growing stage of fall shoots. C. phyllocnistoides is the most abundant parasitoid both in seasonal and spatial dynamics, and demonstrates a Holling type III functional response to CLM. Parasitism varied with the densities of both parasitoid and host. A 1 : 10 ratio was recorded to be an optimal proportion of C. phyllocnistoides to CLM.     

Biological aspects of Cirrospilus neotropicus Diez & Fidalgo (Hymenoptera: Eulophidae), parasitoid of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae)

The biology of Cirrospilus neotropicus Diez & Fidalgo reared on third instar Phyllocnistis citrella Stainton larvae having Citrus limonia Osbeck as host plant, was evaluated under controlled conditions (25 +/- 1 masculineC; 12h photophase). The survival, immatures development, longevity, sex ratio, host feeding and oviposition ratio of C. neotropicus, were registered. Two groups of parasitoid females were evaluated: one, with parasitoids obtained from P. citrella pupae collected in citrus orchards and the other group came from laboratory rearing. These females, after mating, were maintained individually on gerbox containers with honey and pollen as food source. At each 48h, 12 P. citrella larvae were changed. The average biological cycle of the female progenies from orchard and laboratory generation groups were 11.8 and 11.6 days, respectively. The males progenies had biological cycles of 11.6 and 10.9 days, as well. The shortest immature survival period, for both studied groups was the larval (57.3% - orchard group and 57.4% - lab group). The mated females average longevity (21.8 days) was superior than the non mated ones (9.1 days) for the orchard group. The average daily oviposition rate for this last group was also significantly superior (2.8 eggs /day) than the lab group (1.6 eggs / day). The same trend was observed for the average daily host feeding rate (1.7 larvae /day for the orchard group and 0.9 larvae/ day for the lab group). These data suggest that C. neotropicus have potencial as a biological control agent of P. citrella.     

Pathogenicity of entomopathogenic fungi on hibernating pupae of Cameraria ohridella Deschka & Dimic 1986 (Lepidoptera, Gracillariidae). Part 2: Efficacy of entomopathogenic fungi against pupa in her pupal cell

The naked pupae of chestnut leafminer Cameraria ohridella are susceptible for entomopathogenic fungi Paecilomyces fumosoroseus strain P6; Lecanicillium muscarium strain V24; Metarhizium anisopliae strain M72 and Beauveria bassiana strain B412. Their activity at low temperature is advantageous especially for the use in the winter season. (Richter et al., 2007a). Therefore the possibility of infection should be examined in biotest for pupae in their pupal cells on leaf of chestnut at conditions Like in winter. Efficacy of entomopathogenic fungi is decreased, if pupae are in their pupal cells. But fungi, especially L. muscarium, proved the ability to infect pupae of C. ohridella in their pupal cells. Infected pupae moulded in their pupal cells after application. Infection doesn't come from spores. In semi field trials with L. muscarium 60% of pupae were infected in their pupal cells and died after incubation with mouldiness.     

温度对美洲斑潜蝇发育、存活和繁殖的影响

探讨了在光照周期为14L◊10D、R.H.为70%±5%的恒温(12～35℃)条件下美洲斑潜蝇的发育、繁殖和存活,求得美洲斑潜蝇世代的发育起点温度与有效积温分别为8.77℃和295.69日度,给出了温度与各虫态发育速率间的函数关系。20～27.5℃时存活率较高,死亡主要发生在蛹期,35℃下蛹不能羽化。成虫寿命随温度的升高而缩短;种群增长指数于27.5℃时达到最高。     

幼虫密度对甜菜夜蛾生长发育与繁殖的影响

为了研究甜菜夜蛾Spodoptera exigua(Hübner)幼虫的密度对其发育及繁殖的影响,本实验观察了5种幼虫密度下（1,5,10,20,30头/瓶）,幼虫发育和成虫繁殖情况。结果表明：幼虫和蛹历期、存活率和蛹重均差异显著。幼虫和蛹历期均以20头/瓶的最短,1头/瓶的最长,其余随幼虫密度增加而延长;幼虫至蛹存活率以10头/瓶的最高,其余随幼虫密度增加而降低;1头/瓶的蛹最重,显著高于其他密度的,其余随幼虫密度增加而下降。尽管密度间成虫羽化率和产卵前期均无显著差异,但成虫产卵量、寿命和畸形率差异显著。1头/瓶的产卵量最多,其次为10头/瓶的,其余随幼虫密度增加而减少,30头/瓶的产卵量显著少于其他密度的; 密度在1～20头/瓶范围内,雌蛾寿命均较短,显著短于30头/瓶的,而雄蛾寿命以5头/瓶的最短,显著短于其他密度的（10头/瓶除外）,10头/瓶的次之,其余密度间差异不显著;不同幼虫密度下羽化的成虫畸形率差异显著,10头/瓶的最低,其余随幼虫密度增加而升高; 生命表结果表明甜菜夜蛾在10头/瓶下世代存活率和种群增长指数均最高,幼虫密度过低或过高均不利于种群增长;世代存活率（S）和种群增长指数（I）与幼虫密度之间的关系均呈抛物线关系：S =－0.2087x²+2.5694x+211.52 (R²=0.88),I=－0.0552x²+0.9166x+54.168 (R²=0.95)。结果提示幼虫密度影响甜菜夜蛾种群动态的重要生态因子之一。     

Reproduction of three eulophid wasps that parasitise larvae of the citrus leafminer

The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) (CLM), is a citrus pest indigenous to Southeast Asia. It was discovered in Israel in 1994. The pest attacks the young foliage of citrus, and damage is caused by the larvae tunnelling under the epidermis of young leaves, leading to foliage destruction. The present study documents basic biological parameters of three exotic eulophid wasps in the laboratory: Semielacher petiolatus, Quadrastichus citrella and Teleopterus sp. S. petiolatus females preferred to lay eggs in the 3rd larval instar of CLM, but did not lay eggs in the 1st instar. Its development ranged from 9 to 14 days. Female longevity was 30.2±5.9 days, its daily oviposition was 12.16±0.68 eggs/day, the total number of eggs oviposited per female was 278.9±74.1, and the number of CLM larvae parasitised was 260.0±68.3. Q. citrella preferred to lay in the 3rd and 4th instar larvae, but not in the 1st instar, its development ranged from 9 to 14 days, female longevity was 40.6±1.9 days, oviposition came to 8.3±0.6 eggs/day, the total number of eggs oviposited was 281.3±64.9/female and the number of parasitised CLM larvae was 276.5±63.7. Teleopterus sp. preferred to lay eggs in the 3rd larval instar, its development required 11–17 days, female longevity was 28.7±3.8 days, its daily number of offspring was 5.2±0.38 offspring/day and with emergence of 138.9±27.7 offspring/female. This knowledge enabled us to maintain high quality cultures for their releases in Israel.     

Genetic analysis of citrus leafminer susceptibility

Damage caused by the citrus leafminer (CLM), Phyllocnistis citrella, is highly dependent on the citrus flushing pattern. Chemical control is only required in young trees, both in nurseries and in newly established orchards. However, this situation is completely different in countries where the causal agent of citrus canker, the bacterium Xanthomonas axonopodis pv. citri exists. CLM infestation results in a higher incidence of citrus canker infection. Among preventive control strategies that provide environmentally sound and sustainable solutions, resistant or tolerant varieties remain the most economical means of insect control. The objective of the present study is to genetically analyse the resistance/susceptibility to CLM and two other traits that might be related, the deciduous behaviour and leaf area of the tree, in a progeny of citradias derived from the cross between two species with different CLM susceptibility—C. aurantium L. and Poncirus trifoliata—using linkage maps of each parent that include several resistance gene analogues. We detected two antibiosis and six antixenosis putative quantitative trait loci (QTLs) in a random sample of forty-two of those citradias. An important antibiosis QTL (R²=18.8–26.7%) affecting both percentage of infested leaves and number of pupal casts per leaf has been detected in P. trifoliata linkage group Pa7, which is in agreement with the CLM antibiotic character shown by this species, and independent from any segregating QTL involved in its deciduous behaviour. The maximum value for the Kruskal-Wallis statistic of the other putative antibiosis QTL coincides with marker S2-AS4_800 in sour orange linkage map. Given that the sequence of this marker is highly similar to several nucleotide binding site-leucine-rich repeat (NBS-LRR)-type resistance genes, it might be considered as a candidate gene for insect resistance in citrus.