Population dynamics of the chestnut gall-wasp,Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) IV. Further analysis of the distribution of eggs and young larvae in buds using the truncated negative binomial series

Distribution pattern of eggs and the first instar larvae of the chestnut gall-wasp, Dryocosmus kuriphilus, per bud of the chestnut tree was re-examined using the truncatedPoisson and the truncated negative binomial series. The results are as follows:

1. About sixty percent of the distribution are approximated by the truncated negative binomial and another thirty percent by the truncatedPoisson . When the distribution has been approximated by the truncated negative binomial, the show scattered values, some of which are near thePoisson , but the mean value of is about 4 both in eggs and in the first instar larvae.
2. The number of buds which have not been infested by gall-wasps is resulted from various factors as follows: (a) Buds formed after the laying activity of gall-wasps has ceased; (b) Old and shrunk buds which were avoided in laying; (c) Buds in which eggs have died by the time of sampling; and (d) Buds escaping ovipositions by chance. Most of the gall-wasp-free buds located in the middle part of the shoot are accounted for the zero-class expected by the negative binomial series.
3. Brass (1958) moment method for estimating parameters of the truncated negative binomial give good precision within the range of from 1 to 10 and of from 1 to 6.
4. It is concluded that the truncated distributions used are useful for the purpose of analysis of the distribution pattern of the chestnut gall-wasp.

     

Persistence and distribution of insecticidal seed-dressings for control of the wheat bulb fly, Leptohylemyia coarctata

Samples of plants and soil from two experimental sites, one clay loam and one peaty loam, were analysed chemically to try to explain differing results with γ-BHC and dieldrin seed-dressings applied to control wheat bulb fly on different soil types, and to suggest reasons for patchy plant stands and occasional failure to control the pest. Seed dressed with dieldrin yielded more than untreated seed on both sites, whereas seed treated with γ-BHC yielded as much as seed treated with dieldrin on the clay site, but it yielded less than untreated seed on peat. The chemical analyses showed that the poor performance of γ-BHC on the peat site could not be explained by its failure to persist, because the soil still contained considerable quantities of γ-BHC at the time of insect attack. Possible reasons may be sorption of the poison by organic matter making it less available, and deeper sowing, permitting larvae to reach the plants without prolonged contact with the insecticide. Bayer 38156 (O-ethyl S-p-tolyl ethyl phosphonodithioate) and trichloro-nate (O-ethyl O-2,4,5-trichlorophenyl ethyl phosphonothionate) persisted in soil long enough and were sufficiently toxic to wheat bulb fly to suggest that organophosphorus compounds might provide alternatives to chlorinated hydrocarbon insecticides for control of the fly. Analyses made on seeds dressed at the laboratory for the experiment showed that the amounts of insecticide on seeds were smaller than expected and that the amounts on individual seeds differed greatly. Of ten samples of seeds dressed commercially with y-BHC, three carried very little insecticide, and the variations in the other seven samples were greater than with experimentally applied dressings.     

Influence of parental density on the distribution pattern of eggs in the common cabbage butterfly,Pieris rapae crucivora

To investigate the relation between the distribution pattern of eggs and the parental density in the common cabbage butterfly, Pieris rapae crucivora, the countings of egg number per plant were made on both cabbage plants cultivated in the farm and planted in the net house in which the female butterflies were released at various densities. The frequency distribution of eggs fits well to the negative binomial excepting the cases where they agree withPoisson series, and the degree of aggregation expressed as the reciprocal of the parameter, 1/k, tends to decrease as the egg or parental density increases. At the same parental density, however, the distribution of eggs can be described by the negative binomial with a common parameter, k_c, regardless of the difference in the density of laid eggs. In the case where a single female butterfly lays eggs, the spatial pattern of egg distribution is always lean, while its frequencies conform toPoisson or the negative binomial series. This lean changes toward patchy with increasing the parental density. From these results, it is concluded that the degree of aggregation in the distribution of eggs decreases with the increase of the parental density.     

Process generating the ditribution pattern of eggs of the common cabbage butterfly,Pieris rapae crucivora

The process generating the negative binomial in the distribution pattern of eggs of the common cabbage butterfly, Pieris rapae crucivora, was investigated by releasing the female adults in a net house where cabbages were planted. The distribution of butterflies visited and laid an egg or more per plant followed thePoisson series under the uniform light condition, while that of eggs laid per visit conformed to the logarithmic distribution. From these results, it may be concluded that the negative binomial arises from compounding of thePoisson and the logarithmic distribution. The observed frequency of eggs found per plant fitted to the negative binomial with parameter thus computed theoretically. The change in the degree of aggregation with the increase of the parental density was considered in connection with the above results.     

Specificity of accessory gland extracts. in three Delia fly species (Diptera: Anthomyiidae)

Abstract. Extracts of testes and male accessory (paragonial) glands made from three species of Delia (onion fly {D.antiqua) , seedcorn fly (D.platura) , and cabbage fly (D.radicum)) were injected into conspecific virgin females. Extracts of paragonial glands, but not testes, from onion, seedcorn and cabbage fly males stimulated oviposition and suppressed mating when injected into conspecific virgin females. When extracts of paragonial glands from males of these species were injected into heterospecific virgin females, the extracts of D.antiqua and D.platura were fully cross-reactive with respect to oviposition; interspecific injection stimulated oviposition at the level of the conspecific mated controls. Injection of D.radicum extract fully activated the D.antiqua and D.platura ovipositional response. D.antiqua extract caused mating inhibition and partial oviposition in D.radicum; that of D.platura had no effect on either oviposition or mating inhibition in D.radicum. These results suggest that D.antiqua and D.platura are more closely related to one another than either is to D.radicum , and agree with published anatomically-based phylogenies and a genetic distance calculation based on eight enzyme loci. The occurrence of sex peptide cross-reactivity, though asymmetrical, between D.radicum versus D.antiqua and D.platura indicates that, functionally, sex peptides have changed little during the evolution of this genus. An emerging pattern of broad cross-reactivity within genera suggests that sex peptides are not an initiator of reproductive isolation.     

Observations on longevity and fecundity of the sorghum shoot fly, Atherigona soccata (Diptera; Anthomyiidae)

Longevity and fecundity of the sorghum shoot fly, Atherigona soccata Rond. were mainly affected by the adult food. Lack of mating reduced fecundity and affected the rate of oviposition in the females, but did not affect longevity. The mean number of eggs per mated female was 62.8±0.9. Oviposition began at a mean period of 4.7 days after adult emergence. Mean longevity of females and males was 32.6±0.3 and 25.4±0.4, days, respectively.

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Résumé La longévité et la fécondité de Atherigona soccata dépendent avant tout de la nourriture de l'adulte. L'absence d'accouplement réduit la fécondité et modifie le taux de ponte des femelles, mais ne touche pas leur longévité. Le nombre moyen d'ufs pondus par femelle accouplée est 62,8±0,9 (extrêmes 10–167). La ponte commence en moyenne 4–7 jours après l'émergence des adultes (extrêmes 2 et 14 jours). La longévité moyenne des femelles et des mâles est respectivement de 32,6±0,3 jours et 25,4±0,4 jours.

     

Ovipositional behaviour and host-plant preference of the sorghum shoot fly, Atherigona soccata (Diptera; Anthomyiidae)

The distribution of eggs on sorghum by Atherigona soccata Rond. and host preference for oviposition were studied. The female laid her eggs more or less evenly on sorghum leaves, laying one or two eggs per leaf. Under field conditions eggs were most frequently laid on the third leaf, followed by the second leaf, while under insectary conditions the second leaf was preferred to the third. Sorghum bicolor was markedly preferred to other graminaceous plant species, Digitaria scallarum, Rottboellia exaltata, Setaria verticillata and Panicum maximum.

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Résumé Nos observations montrent que les femelles d'Atherigona soccata répartissent leurs ufs plus ou moins au hasard sur les feuilles de Sorgho, déposant 1 à 2 ufs par feuille. Dans les conditions naturelles les ufs sont plus fréquemment déposés d'abord sur la 3ème feuille, puis sur la 2ème feuille, tandis qu'en insectarium la 2ème feuille est préférée à 3ème. Sorghum bicolor est nettement préféré à d'autres espèces de graminées, comme Digitaria scallarum, Rottboellia exaltata, Setaria verticillata et Panicum maximum.

     

Experimental studies on the distribution of the aphid counts

The present paper dealt with the sequential changes of the distribution pattern of apterous females aphid populations, that were artificially settled at the beginning on the experimental barley ‘field'. The aphids were settled at random or even with a fixed denisty per plant. For five or six days after the settling, the number of individuals followed the negative binomial distributions in all cases while the parameters k and p were varying. The estimated values of k were rather small for the first one week after the settling, which may suggest that the number of moving aphids between plants was relatively small and the degree of concentration expressing the intrinsic increase was high. After that, as the number of individuals increased, the number of moving aphids between plants would be considered to be increased. It was found that with the lapse of time the degree of concentration decreased or k became larger. The distribution of aphids per blade in a plant was also described briefly.     

Quantitative analysis of ovipositional behavior: Effects of a host-plant chemical on the onion fly (Diptera: Anthomyiidae)

Behavioral responses of female onion flies, Delia antiqua (Meigen), to hostplant cues were quantified during encounters of individual flies with onion plants and onion foliar surrogates. The behavioral repertoire of such females included sitting, grooming, running up and down foliar surfaces, extension of the proboscis such that the labellum contacted foliar and soil surfaces, movements of the tip of the abdomen over surfaces (surface probing), subsurface probing of soil crevices with the ovipositor, and oviposition. Sequences of behaviors preceding oviposition were probabilistic rather than highly stereotyped but generally followed the order given above. Foliar surrogates were used to determine the effects of n-dipropyl disulfide (Pr₂S₂) on the sequence of behaviors leading up to oviposition. The addition of a Pr₂S₂-treated surrogate to a cage increased the frequency of alighting on that surrogate but also increased alighting on a nearby foliar surrogate without Pr₂S₂. After alighting, females encountering surrogates treated with Pr₂S₂ had shorter latencies to proboscis extension and surface probing, spent less time sitting and grooming, and had runs of shorter duration. These females were also more likely to make the transition from probing of surfaces of foliage and soil to subsurface probing of soil crevices and oviposition. Thus, rather than mediating a particular step in the behavioral sequence, Pr₂S₂ played a role throughout the sequence leading up to oviposition. Collectively, these data and past studies on the onion fly support the hypothesis that egglaying is triggered by a temporal summation of inputs to the central nervous system from various sensory modalities rather than strict behavioral chaining, with each transition effected by some unique cue.     

Spatial distribution of the green peach aphid used in estimating the populations of gynoparae

Summary In 2 years, during the initial invasion of peach leaves by the green peach aphid,Myzus persicae (Sulzer), the number of gynoparae was low, and the distribution on leaves was random. Then as the mean number increased, the distribution became intermediate and could not be distinguished from either a Poisson or a negative binomial. Finally, as the mean continued to increase, the variance increased rapidly, and the population was found to fit a negative binomial distribution. Thus the aggregation response was verified because the dispersion pattern fitted a contagious distribution. A sampling plan was devised by which the dispersion parameterk was used to estimate the density of aphids per leaf based on the percentage of leaves infested. Sampling the third year of the study confirmed the validity of the sampling parameter that had been calculated from data for the 2 previous years.     

The character of soldier fly distribution (Diptera,Stratiomyidae) in Eastern Europe

A total of 81 soldier fly species (Diptera, Stratiomyidae) belonging to 4 subfamilies occur in Eastern Europe (the East European Plain and Ciscaucasia). This fauna is compared to that of Western Europe and the chorological analysis of species found in Eastern Europe is given. According to the type of the geographic range, 13 species-groups and several subgroups were distinguished. Northern range borders in Eastern Europe and eastern borders of distribution of some species are discussed. The ratio between different subfamilies in the number of species in different parts of the territory under study is demonstrated.     

Laboratory transmission and in vivo incubation of Entomophthora muscae (Entomophthorales: Entomophthoracae) in the onion fly,Delia antiqua (Diptera: Anthomyiidae)

A high-moisture infection chamber was used for the in vivo transmission of Entomophthora muscae within laboratory populations of the onion fly, Delia antiqua. This cadaver-to-fly transmission procedure provided an average experimental infection rate well above 95%. Laboratory infection and temperature-dependent incubation rates of E. muscae were further examined in adult populations of D. antiqua. The time from initial exposure until host death and pathogen sporulation was accurately predicted using a second-order function of the incubation temperature. A developmental base temperature of approximately 5°C was estimated, with 105 degree-days being the average number of heat units required between host infection and death. E. muscae transmission between D. antiqua and D. platura, two insect pests typically associated with Michigan onion production, was verified under laboratory conditions.     

Modification of female onion fly,Delia antiqua (Meigen), reproductive behavior by male paragonial gland extracts (Diptera: Anthomyiidae)

Egg depositional rates of onion flies, Delia antiqua(Meigen), injected thoracically with extracts of male paragonial glands were identical (14.5 eggs/female/ day) to those of normally mated females. Moreover, when continuously exposed to males, extract-injected females refused to mate and produced unfertilized eggs for the duration of the > 15- day experiment. For this normally monocoitic dipteran, <1 male equiv of paragonial secretion completely reproduced the ovipositional responses characteristic of normal mating, and this effect required no involvement of the genitalia or genital chamber. We suggest that the receptor for the active chemical (s) (sex peptide?) would be an excellent target for biorational insect control by sterilization. Moreover, these primer sex pheromones might play an important role in insect reproductive isolation and evolution.     

Models of the spatial pattern of egg population of Ranunculus leaf mining fly,Phytomyza ranunculi (Diptera: Agromyzidae), in host leaves

This paper considers two kinds of model of the spatial pattern of egg distribution of the Ranunculus leaf mining fly, Phytomyza ranunculiSchrank , as a step to determining the effect of the distribution upon the parasitism of this species by the eulophid parasite, Kratochviliana sp.. Each model incorporates submodels in several important stages of both the processes of visiting and subsequent oviposition by the fly. Model 2 is more general than model 1, because the former also includes the effect of oviposition restraint. Both models fitted well the egg distribution on fresh plants and on exploited plants. The fitting similarity on exploited plants is due to the fact that there were not so many heavily exploited leaves which lead to oviposition restraint, owing to the low density of mature larvae contained in the leaves. These models will be applicable to the distribution of larvae as well as eggs, because most larvae remain in the leaf where they occurred as eggs, until emerging just before pupation. This paper also discusses by use of these models the fact that this fly tends to effectively avoid excessive oviposition in leaves by laying fewer eggs per visit and visiting leaves more sparsely and also by refraining from further oviposition on leaves exploited heavily by mature larvae.