Dynamics of Populations.

Varley, G. C.; Boer, P.J. den; Gradwell, G. R.

doi:10.2307/2258936

Cited by 49 publications

(10 citation statements)

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“…The relationship, though not very clear, can be interpreted as an inverse density dependent relationship (Varley et al 1973) i.e. the proportion of attacked scales decreases as the density of the population of 5. oleae increases.…”

Section: Resultsmentioning

confidence: 98%

Preliminary results for the eνaluation of the action of Saissetia oleae parasites in Corfu.

Stratopoulou¹,

Kapatos²

2017

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The action of parasites of Saissetia oleae (Oliv.) (Homoptera-Coccidae) is studied in Corfu from 1980 in the framework of an ongoing project on the population dynamics of Saissetia oleae.Results obtained during the period 1980-1983 from 17 experimental sites indicate the following: a) the population of S. oleae increased in 1981 but from 1982 it declined to very low levels; following the overall decline of the host population, parasitization rates of third instar larvae (mainly by Metaphycus helvolus Comp.) were relatively low and ranged from 2.1 % to 6.7% for the autumn period and from 14.6% to 29.4% for the spring period; this does not minimize the possibility that Metaphycus helvolus plays an important role on the regulation of 5. oleae populations; b) a considerable proportion of females of S. oleae is attacked during summer by Metaphycus lounsburyi How. (an internal parasite on preovipositing females), Moranila calif arnica How. and Scutellista cyanea Motsch. (egg predators), but their significance upon the population system of 5. oleae is not expected to be great. The action of Metaphycus lounsburyi in spring, when the peak of the suitable stage occurs (i.e. fourth instar larvae), appears to be very low, at least for these three years. Its action is delayed and most of the specimens of this parasite emerge from ovipositing females in early summer. Among the species attacking S. oleae females, M. californica (recently introduced in Corfu) was the most abundant and it might be worthy to be introduced to other parts of Greece too.

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Section: Resultsmentioning

confidence: 98%

Preliminary results for the eνaluation of the action of Saissetia oleae parasites in Corfu.

Stratopoulou¹,

Kapatos²

2017

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“…Even though winter moth eggs are laid on bare tree branches (Varley et al 1973 ) and are thus exposed to photoperiod during their entire development, it could be that developing embryos only start using photoperiodic information close to hatching. During most of their development, winter moth eggs are an opaque orange and embryos are nestled deep inside the egg (Gaumont 1950 ; van Dis et al 2021 ).…”

Section: Discussionmentioning

confidence: 99%

“…Instead, egg development is continuous with embryos remaining temperature sensitive throughout development (van Dis et al 2021 ) – similar to, for example, the pea aphid, Acyrthosiphon pisum (Shingleton et al 2003 ). Since winter moth eggs are exposed to photoperiod during development in natural conditions (Varley et al 1973 ) and photoperiod can be involved in the induction, maintenance, and termination of insect diapause (Denlinger 2002 ; Tauber and Tauber 1976 ), winter moth eggs might similarly be sensitive to photoperiod during development. However, it remains unknown whether photoperiod also plays a role in regulating the timing of winter moth egg dormancy, and if so, how it interacts with temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature has an overriding role compared to photoperiod in regulating the seasonal timing of winter moth egg hatching

van Dis,

Salis,

Visser

2024

Oecologia

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To accurately predict species’ phenology under climate change, we need to gain a detailed mechanistic understanding of how different environmental cues interact to produce the seasonal timing response. In the winter moth (Operophtera brumata), seasonal timing of egg hatching is strongly affected by ambient temperature and has been under strong climate change-induced selection over the past 25 years. However, it is unclear whether photoperiod received at the egg stage also influences timing of egg hatching. Here, we investigated the relative contribution of photoperiod and temperature in regulating winter moth egg development using two split-brood experiments. We experimentally shifted the photoperiod eggs received by 2–4 weeks compared to the actual calendar date and measured the timing of egg hatching, both at a constant temperature and in combination with two naturally changing temperature treatments – mimicking a cold and a warm year. We found an eight-fold larger effect of temperature compared to photoperiod on egg development time. Moreover, the very small photoperiod effects we found were outweighed by both between- and within-clutch variation in egg development time. Thus, we conclude that photoperiod received at the egg stage does likely not play a substantial role in regulating the seasonal timing of egg hatching in the winter moth. These insights into the regulatory mechanism of seasonal timing could have important implications for predicting insect climate change adaptation, as we might expect different targets of selection depending on the relative contribution of different environmental cues.

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“…Aspek yang penting dalam mengkaji dinamika populasi suatu serangga termasuk lalar sciarid adalah pertumbuhan dan perubahan populasi serta faktor-faktor yang mempengaruhi populasi tersebut (Varley et al, 1973). Dengan demikian, penelitian dinamika populasi tersebut tidak terlepas dari penerapan matematika dalam bidang biologi atau ekologi populasi.…”

Section: Pendahuluanunclassified

“…Resistensi Jika populasi dianggap merupakan suatu proses yang kontinyu, maka model matematika untuk perubahan populasi eISSN: 2655-8122 serangga dapat diturunkan dari persamaan diferensial (Varley et al 1973). Misalnya, banyaknya populasi pada waktu t adalah N, maka laju pertumbuhan populasi dN/dt dinyatakan sebagai : dimana m r adalah laju intrinsik peningkatan populasi alami.…”

Section: Pendahuluanunclassified

Tabel Hidup Lalat Jamur Tiram, Bradysia ocellaris

Rostaman¹

2023

metamorfosa

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Lalat sciarid, Bradysia ocellaris Comstock, merupakan jenis serangga hama baru pada budidaya jamur tiram di Bandung dan daerah lainnya di Jawa Barat. Berdasarkan informasi, lalat sciarid telah tersebar luas di berbagai negara. Penelitian ini bertujuan untuk mengetahui parameter tabel hidup serangga tersebut. Parameter ini penting dalam menduga dinamika populasi serangga. Serangga B. occelaris dipelihara di laboratorium dengan menggunakan media jamur tiram sebagai pakannya. Hasil penelitian menunjukkan bahwa laju intrinsik peningkatan populasi () 0, 157, laju reproduksi bersih () 23 individu/generasi dan waktu generasi rata-rata (T), 20,5 hari. Informasi ini penting untuk melihat kemampuan reproduksi serangga hama dalam waktu tiga minggu.

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Dynamics of Populations.

Cited by 49 publications

References 0 publications

Preliminary results for the eνaluation of the action of Saissetia oleae parasites in Corfu.

Preliminary results for the eνaluation of the action of Saissetia oleae parasites in Corfu.

Temperature has an overriding role compared to photoperiod in regulating the seasonal timing of winter moth egg hatching

Tabel Hidup Lalat Jamur Tiram, Bradysia ocellaris

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