Length Of Pre-oviposition Period Research Articles

Age in Relation to Copulation, Egg Development, and Multiple Mating Behavior in the Coconut Palm Pest Brontispa longissima (Coleoptera: Chrysomelidae)

Abstract To clarify the reproductive properties of the coconut palm pest, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), we investigated in the laboratory the diel periodicity in copulation, effect of adult age after emergence on copulation and ovarian development, reproductive development in relation to female age, and the possibility of multiple mating. The beetles used in this study were reared in the laboratory and were fed an alternative food plant, narrowleaf cattail, Typha domingensis Pers. (Typhaceae). Copulation occurred throughout the 24-h cycle but mostly occurred in the photophase with two peaks, one at the onset of lights-on and the other 8–12 h after lights-on, indicating that most copulation activity in B. longissima in the field occurs in the early morning and the afternoon. Females could copulate immediately after emergence, whereas males began copulating 3 wk after emergence. Ovaries of females started to develop in the absence of mating and were correlated with adult age. Mature males could copulate with females regardless of ovarian developmental stage, and females with undeveloped ovaries accepted copulation attempts. Our study showed that the timing of copulation during the preoviposition period would not affect numbers of eggs laid, length of preoviposition period, or viability of eggs. B. longissima adults engaged in multiple mating.

Differences in haemolymph proteins in relation to diapause and wing dimorphism inPyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

Three different cultures of dimorphic bug,Pyrrhocoris apterus, were analyzed concerning diapause and its relation to wing morph pattern. The proportion of macropterous bugs was considerably higher (36%) in the Mediterranean culture from Israel than that (1.3%) in the temperate culture from the Czech Republic. The macropterous morph- and brachypterous morphrelated types of reproduction arrest, differing by the length of pre-oviposition period, were distinguished in cultures analyzed. The reproduction arrest with an average pre-oviposition period of 38.2 days in Mediterranean macropters and 18.5 days in macropters from selected macropterous strain, was found to be typical for macropterous morph. Two different photoperiodic conditions induced macropterous morph-related reproduction arrest, the long-day (18 h light-6 h dark) photoperiod in macropterous strain macropters and the short-day (12 h light-12 h dark) photoperiod in Mediterranean macropters. The brachypterous morph-related reproduction arrest, characterized by pre-oviposition period longer than 90 days, occurred predominantly in diapausing brachypterous bugs. While the hibernal diapause of brachypterous bugs was characterized by a very high level of the 78- and 82-kDa proteins in haemolymph, their content in haemolymph of macropters during macropterous morph-related reproduction arrest was almost as low as in the reproductive adults. The variation of reproduction arrest in relation to wing dimorphism represents an important feature in the life strategy ofP. apterus.

Reproductive Success of the Black Vine Weevil, Otiorhynchus sulcatus .(F.), 1 Fed Different Foliar Diets and Evaluation of Techniques for Predicting Fecundity

Reproductive success of the black vine weevil, Otiorhynchus sulcatus (F.), fed different foliar diets was compared to evaluate suitability of known and potential hosts for adults. Foliar diets, arranged in order of decreasing fecundity, were Taxus cuspidata Sieb. and Zucco., T. canadensis Marsh., Kalmia latifolia L., and Cornus florida L. Fecundity and length of preoviposition period were negatively correlated, indicating that the latter could be used to forecast potential fecundity. Weight gain of adults during the preoviposition period, foliar N content, and changes in water content of foliage fed to weevils varied significantly between some of the diets but were not consistently correlated with egg production. Possible reasons for differential fecundity and for general absence of weevils from northeastern forests are discussed.

タマナヤガの各発育段階の諸形質に及ぼす幼虫密度の影響

A laboratory experiment was conducted to determine whether the characters of the black cutworm, Agrotis ipsilon, are affected by larval density. The larvae were reared at densities of 1, 2, 3, 5, 10 and 30 individuals per vessel at 25°C and a 16 : 8h light : dark cycle. The rate of larval and pupal development, the length of preoviposition period and longevity of the male moths were not affected by the density during larval period. The weight of pupae, fecundity and longevity of the female moths were, however, reduced when the larvae were reared at high density. The mortality prior to the 5th moult was low, and the increased mortality in crowded culture occurred mainly between the last larval instar and pupal stage. The aggressive behaviour of the mature larvae was a major factor affecting the density-dependent mortality.

Oviposition of the American Dog Tick (Acarina: Ixodidae)

Female American dog ticks, Dermacentor variabilis (Say), were engorged on bovines and were held at 27°C and > 80% relative humidity under a photocycle of 12 hours light: 12 hours dark. The average weight (0.398 g), length of preoviposition period (5.3 days), and number of eggs laid per female (3276.8) did not differ significantly for groups of females disturbed daily by removal of eggs and groups of females allowed to oviposit undisturbed. The weight of a newly laid egg averaged 77 µg; the average weight of an egg weighed after oviposition ceased but before hatch began averaged 66 µg. With all females, the number of eggs per female was highly significantly correlated with the weight of the female. With undisturbed females, the length of the preoviposition period was negatively correlated with weight; this was not true of the disturbed females. The Index of Reproduction Efficiency (number of eggs per weight of female) and the Index of Conversion Efficiency (weight of eggs per weight of female) were correlated with the weight of the undisturbed females but not the disturbed females. Peak daily oviposition, an average 381.5 eggs per female, occurred on the 3rd day of oviposition. An average > 300 eggs per female was laid on days 2–5; thereafter the rate of oviposition gradually declined. The length of the oviposition period (average 20 days) was highly significantly correlated with the weight of the female and with the number of eggs laid. The average minimum incubation period was 20 days.