Competitive displacement ofAnagyrus antoninae [Hym.: Encyrtidae]. by its ecological homologueNeodusmetia sangwani [Hym.: Encyrtidae]

The displacement ofAnagyrus antoniaae Timberlake byNeodusmetia sangwani (Rao) was demonstrated by reduced parasitism by the former in two localities after the latter was introduced into these sites. The competitive factors were: (1) the host-regulative action ofN. sangwani maintained a low host reciprocal balance, and (2) the inability of the female ofA. antoninae at the prevailing host density to find hosts sufficient for reproduction. The lack of competitiveness ofA. antoninae was a result of its inability to develop at high vapor deficits.     

Soil-applied imidacloprid is translocated to nectar and kills nectar-feeding Anagyrus pseudococci (Girault) (Hymenoptera: Encyrtidae)

Behavior was altered and survivorship was reduced when parasitoids, Anagyrus pseudococci (Girault) (Hymenoptera: Encyrtidae), were fed flowers from buckwheat, Fagopyrum esculentum L. (Polygonaceae), treated with soil applications of imidacloprid (Marathon 1% G). Parasitoids at 1 d had significantly reduced survivorship of 38 +/- 6.7% on label rate and 17 +/- 4.2% on twice label rate compared with 98 +/- 1.2% on untreated flowers. Parasitoids trembled 88% on label rate and 94% on twice label rate compared with 0% on untreated flowers. Residue analysis on a composite sample of 425 flowers showed that imidacloprid concentration was 6.6 +/- 1.0 ppm (16 ppb/flower) in label rate, 12.3 +/- 2.7 ppm (29 ppb/flower) in twice label rate, and 0 ppb in untreated flowers. The hydroxy metabolite concentration was 1.1 ppm (2.4 ppb/flower) in label rate, 1.9 ppm (4.4 ppb/flower) in twice label rate, and 0 ppm in untreated flowers. The olefin metabolite concentration was 0.2 ppm (0.5 ppb/flower) in label rate, 0.5 ppm (1.1 ppb/flower) in twice label rate, and 0 ppm in untreated flowers. Soil-applied imidacloprid used at flowering may be translocated to nectar in higher concentration compared with the imidacloprid seed treatment Gaucho. Considerable research has studied effects of Gaucho-treated canola, sunflower, and maize on behavior and mortality of Apis mellifera L. In our laboratory, we showed that translocation of imidacloprid to flowers reduced survivorship and altered behavior of pink lady beetle, Coleomegilla maculata DeGeer (Smith and Krischik 1999) and green lacewing, Chrysoperla carnea Stephens (Rogers et al. 2007).     

Host selection behaviour and specificity of the solitary parasitoid of mealybugs Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera,Encyrtidae)

The host selection behaviour of Anagyrus sp. nr. pseudococci was compared in no-choice tests among five mealybug species of different geographical and phylogenetic origin, including the Mediterranean native host, Planococcus ficus and four exotic mealybug species, one of the same genus, Pl. citri, two Pseudococcus species, Ps. calceolariae and Ps. viburni and a more distant one, Phenacoccus peruvianus. All five studied mealybug species were recognised by the parasitoid as potential hosts and parasitised, but the behavioural pattern of host recognition, host handling and the level of host acceptance of Anagyrus sp. nr. pseudococci significantly varied among the five studied species, indicating a clear preference for the two Planococcus species, Pl. ficus in particular. The results suggest that A. sp. nr. pseudococci has a broader host range and a more generalist behaviour in comparison with other Anagyrus species. Practical implications of the findings are discussed.     

The palaearctic species ofBothriothorax (Hym., Encyrtidae) allied toB. paradoxus (Dalman)

Résumé Une espèce nouvelle deBothriothorax est décrite et une clef d'identification est donnée pour les espèces apparentées àB. paradoxus (Dalm.).      

Defense Response of Native and Alien Mealybugs (Hemiptera: Pseudococcidae) Against the Solitary Parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

The host behavioral and immune (encapsulation) defenses against the parasitoid Anagyrus sp. nr. pseudococci were compared for five mealybug species with different phylogenetic relationships and geographical origins: i) a Mediterranean native mealybug species, Planococcus ficus, with a long co-evolutionary history with the parasitoid; ii) three alien mealybugs species, Planococcus citri, Pseudococcus calceolariae and Pseudococcus viburni, with a more recent co-evolutionary history; and iii) a fourth alien mealybug species, Phenacoccus peruvianus, with no previous common history with the parasitoid. Three host defense behaviors were registered: abdominal flipping, reflex bleeding and walking away. The native host Pl. ficus and its congener Pl. citri exhibited the lowest probability of defense behavior (0.11?±?0.01 and 0.09?±?0.01 respectively), whereas the highest value was observed in P. viburni (0.31?±?0.02). Intermediate levels of defense behavior were registered for Ps. calceolariae, and Ph. peruvianus. The probability of parasitoid encapsulation was lowest and highest for two alien host species, Ph. peruvianus (0.20?±?0.07) and Ps. viburni (0.86?±?0.05), respectively. The native host Pl. ficus, its congener Pl. citri and Ps. calceolariae showed intermediate values (0.43?±?0.07, 0.52?±?0.06, and 0.45?±?0.09, respectively). The results are relevant with respect to biological control and to understand possible evolutionary processes involved in host range of A. sp. nr. pseudococci.     

Suitability of five mealybug species (Hemiptera,Pseudococcidae) as hosts for the solitary parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

Anagyrus sp. nr. pseudococci is an endoparasitoid which has been used as a biological control agent of mealybug pests. In this study, we compared the suitability of five mealybugs species with different phylogenetic relationships and geographical origins as hosts of this parasitoid. The selected mealybugs were: (1) a Mediterranean-native species, Planococcus ficus, sharing a long co-evolutionary history with the parasitoid; (2) three exotic species, the Afrotropical Planococcus citri, the Australasian Pseudococcus calceolariae and the Neotropical Pseudococcus viburni, with a recent history; and (3) the Neotropical Phenacoccus peruvianus, with no previous common history with the parasitoid. Host suitability was assessed based on different fitness parameters, such as body size, developmental time, emergence rate and sex ratio. The parasitoid was able to complete development in all mealybug species. Nevertheless, its emergence rate significantly varied among mealybug species, with the highest values observed in Pl. ficus and Pl. citri, intermediate values in Ps. calceolariae and the lowest ones in Ps. viburni and Ph. peruvianus. The body size of adult wasp females varied with host suitability and was positively correlated with other measures of parasitoid fitness, including the emergence rate and the sex ratio. The parasitoid developmental time differed among mealybug species but did not correlate with any other measure of fitness. A female biased sex ratio was found in the parasitoid progeny emerged from all mealybug species, except in Ps. viburni and Ph. peruvianus. There was a direct relationship between the proportion of females in the parasitoid progeny and the emergence rate.     

Developmental time,longevity, reproductive capacity and sex ratio of the mealybug parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

Key biological parameters of Anagyrus sp. nr. pseudococci reared on the citrus mealybug Planococcus citri (Risso) were determined. The mean longevity of female wasps was 21.1 days, the median lethal time (LT₅₀) was 22 days, the mean number of offspring per female was 30.2 wasps and the sex ratio of the progeny was slightly male biased (1.1 males per female). Wasps fed with water showed a significantly lower longevity compared to that recorded for wasps fed with syrup for bee nutrition mixed with water. The longevity of female wasps was significantly higher compared to males when the syrup-water solution was provided as food. Longevity was significantly higher for female wasps fed with syrup and water in comparison with those exposed to host mealybugs. The mean development time of female and male wasps was 14.7±0.1 and 14.5±0.1 days, respectively.     

Life histories ofPsyllaephagus yaseeni (Hym., Encyrtidae) andTamarixia leucaenae (Hym., Eulophidae), parasitoids of the leucaena psyllidHeteropsylla cubana

Age specific fecundity of two parasitoids,P. yaseeni andT. leucaenae, of the leucaena psyllidH. cubana, were studied under laboratory conditions. At 25 °C,P. yaseeni had a greater fecundity (R₀=192.9)_thanT. leucaenae (R₀=71.2);T. leucaenae however had a lower sex ratio (about 99 % females) thanP. yaseeni (about 50 % females). Innate capacity for increase (r_m=0.236) ofT. leucaenae was higher thanP. yaseeni (r_m=0.188). Developmental rates of the parasitoids were examined at constant and fluctuating temperatures and equations of the rate of development against temperature were calculated. At 25 °C, mean generation times were 28.0 and 18.1 days forP. yaeseeni andT. leucaenae respectively. At temperatures of 21.5, 25, and 30 °C total development times (egg to adult) were 28.5, 21.9, and 14.7 days inP. yaseeni and 19.2, 12.6, and 9.5 days inT. leucaenae respectively. The level of parasitism was low and pupal mortality was high at the lower temperature of 21.5 °C for both parasitoids. Both parasitoids showed poor survivorship at 100 % RH,P. yaseeni survived particularly well (32 days) at a temperature of 21.5 °C and 44 or 76 % RH. P. yaseeni allocated about 58 % females to first instar psyllid nymphs but only 12 % females to second instars. About 99 % of allT. leucaenae births were females. Significantly largerT. leucaenae females emerged from fifth instar parasitized nymphs than third or fourth instars.     

Sustained biological control of the cassava mealybugPhenacoccus manihoti [Hom.: Pseudococcidae] byEpidinocarsis lopezi [Hym.: Encyrtidae] in Nigeria

Following the successful introduction ofEpidinocarsis lopezi (De Santis) for biological control of the cassava mealybug (CM)Phenacoccus manihoti Mat.-Ferr. in southwestern Nigeria in 1981 and 1982, 11 groups of cassava fields were sampled every 2 weeks up to 1988 for impact assessment. After 1984, CM populations remained mostly below 10 per tip despite the presence of native hyperparasitoids, demonstrating the long-term success of biological control byE. lopezi in the region. Indigenous polyphagous coccinellids were found only during peak host densities, whereas the specificE. lopezi was common throughout the year. During some periods, percentage parasitism indicated delayed density dependence. Since 89% of all sampled cassava tips had no CM at all and the parasitisme is very mobile, parasitization rates were also calculated for individual infested tips (N=4,878). Parasitism increased slightly with host density on tips having between 1 and 10 CM of the 3^rd and 4^th instars, indicating positive density dependence. Such tips comprised 64% of all infested tips. At higher host densities, parasitism rates fell rapidly. The results are discussed in view of different theories on population regulation by biological control agents.      

The establishment ofMetaphycus helvolus (Compere) [Hym. Encyrtidae] onSaissetia oleae (Bern.) [Hom. Coccidae] in olive groves in Greece

Résumé Une souche pure de l'EncyrtideMetaphycus helvolus Compere a été importée de Californie par airfret et directement relachée sur des Oliviers attaqués par la CochenilleSaissetia oleae Bern. près de Chania (Crète) en octobre 1962. En dépit du très rigoureux hiver qui suivit et, malgré les applications périodiques d'insecticides dirigées contre d'autres ravageurs, le parasite introduit est maintenant bien établi. En un an, le nombre desSaissetia fut notablement réduit dans le site du lacher originel; en 1964 et 1965, la Cochenille y était pratiquement inexistante. Une légère recrudescence de la population de Cochenille s'est manifestée en automne 1966 mais les Insectes étaient bien parasités. Fin 1966 et début 1967,M. helvolus s'était spontanément installé jusqu'à 24 km du point d'introduction et se rencontrait dans l'ensemble de la zone de Chania. L'espèce s'est probablement dispersée au-delà mais l'échantillonnage n'a pas été réalisé dans d'autres zones. L'espèce endémiqueMetaphycus flavus How. n'a pas été retrouvée en 1966–1967 dans la zone de Chania alors que ce parasite était commun auparavant. Il a été apparemment remplacé parM. helvolus.

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This study was made possible by financial support from the Greek Ministry of Agriculture within the framework of a project for the control of olive pests. The contribution of the second author was made possible by his appointment as a Fulbright Research Scholar at the Benaki Phytopathological Institute, Kiphissia, Athens, Greece. Support for a portion of these studies was given by NSF Grant G-20870. The authors gratefully acknowledge the help of Mr. N. Psyllakis of the Agricultural Research Station of Chania, who made some of the recovery attempts. Especial thanks are due to Mr. Howard Lorbeer, Manager of the Fillmore Citrus Protective District Insectary, who furnished theM. helvolus for our studies.     

Histochemical and histophysical aspects of silk secretion in Melipona quadrifasciata (Hym., Apoidea)

Summary Acid and neutral polysaccharides exist in the secretion of the silk glands of Melipona quadrifasciata during the entire functional stage, except in the late 5th instar. However, only from the 3rd instar on is a molecularly oriented structural protein present. The following evidence indicates that this protein is not collagen: (1) the optical sign of its birefringence does not become reversed after von Ebner's reaction, and (2) its secretion can be detected when the cell nucleus attains a ploidy degree optimal for secretory activity. This is at first observed in the distal part of the glands and then throughout the organ.Stipendiat der Alexander von Humboldt-Stiftung.     

Impact of mating on Anagyrus kamali Moursi (Hym., Encyrtidae) lifetime fecundity, reproductive longevity, progeny emergence and sex ratio

Abstract: The solitary endoparasitoid Anagyrus kamali Moursi (Hym., Encyrtidae) and the Hibiscus mealybug Maconellicoccus hirsutus Green (Hom., Pseudococcidae), were used as a parasite/host model to test the effect of mating on several fitness parameters, i.e. longevity, lifetime fecundity, progeny emergence and sex ratio. At 27 ± 2°C, 8 h light : 16 h dark, mating significantly affected the survival of male parasitoids. Virgin males lived longer (32.2 ± 9.51 days) than mated males (23.9 ± 7.52 days). Female longevity (40.7 ± 16.3 days for virgins and 36.2 ± 10.7 days for mated females) was not affected by mating. The lifetime fecundity of female parasitoids and their oviposition period was not significantly affected by mating. However, the number of hosts parasitized was greater for mated wasps (7.54 ± 4.85 hosts parasitized/day) compared with virgin ones (5.12 ± 2.19 hosts parasitized/day). This resulted in greater progeny production from mated A. kamali females. The progeny of virgin females consisted only of males, whereas the mated ones had a more female‐biased sex ratio. The lowest sex ratio (0.41 M/F ± 0.123) was attained when females had free access to males and were multi‐mated.     

Influence of crucifer cropping system on the parasitism ofPlutella xylostella (Lep., Yponomeutidae) byCotesia plutellae (Hym., Braconidae) andDiadegma semiclausum (Hym., Ichneumonidae)

Field experiments were conducted to study the influence of cabbage monoculture and mixed cropping on the parasitism of diamondback moth,Plutella xylostella (L.), a destructive pest of all crucifers, by 2 larval parasites,Diadegma semiclausum Hellén andCotesia plutellae Kurdjumov. There was no significant difference in parasitism by either species whether cabbage was planted in insecticide-free monoculture or in mixed cropping with 8 noncrucifers which were sprayed twice a week with chemical insecticides mevinphos, methamidophos and permethrin. Population ofP. xylostella increased as the cabbage plants grew older. Parasitism byC. plutellae was higher soon after cabbage transplanting but decreased as the plants grew older. Parasitism byD. semiclausum was very low soon after cabbage planting but increased as the plants grew older. A significant negative correlation was found betwen parasitism byC. plutellae andD. semiclausum. In a caged field study where only one parasite species was used in an individual cage, parasitism ofP. xylostella by both species decreased as theP. xylostella population increased. This is believed to be due to the absence of competition between the two parasites inside the cage. There was no relationship between host-plant age and parasitism ofP. xylostella larvae by either parasite species.     

Control ofSaissetia oleae (Hom.: Coccidae) in Cyprus through establishment ofMetaphycus barletti andM. Helvolus (Hym.: Encyrtidae)

In Cyprus the black scale,Saissetia oleae (Olivier) is a pest primarily of olive,Olea europaea L., but it also attacks several other plants, among which areCitrus spp. and oleander,Nerium oleander L. The parasitoidsMetaphycus bartletti Annecke &; Mynhardt andMetaphycus helvolus (Compere) have been imported from France, massreared and permanently established in Cyprus. Following limited releases of these parasitoids, populations ofS. oleae have been reduced from outbreak levels to almost non-existence and remained at such low levels even after discontinuation of these releases.     

Description ofOligosita tominici n. sp. [Hym., trichogrammatidae] and notes on the hosts ofAnagrus atomus (L.) andAnaphes autumnalis Foerster [Hym. Mymaridae]

Oligosita tominici n. sp. is described, bred fromErythroneura eburnea (Cicadellidae) and a key to theminima-group is given.Anagrus atomus (L.) is recorded fromErythroneura eburnea, too, andAnaphes autumnalis Foerster is bred from an egg ofTipula autumnalis Loew; it is the first record of an egg-parasite ofTipulidae.