A Fixative for Use in Dissecting Insects

Can. Ent. 107: 119-128 (1975) The biology of Coenagrion angulaturn Walker and C . resolutum Hagen in Saskatchewan has been studied. In these species embryonic development begins as soon as the eggs are laid and is completed in the field within 3 weeks. Larval development is rapid and larvae in the final instar were first collected before the middle of September. Development ceases during the first 2 weeks of October when the water temperature is about 2°C. By this time the majority of larvae are in the last three instars. Larvae overwinter frozen in the ice 15 to 20 cm below the pond surface. They are able to survive temperatures as low as -5" to -6°C though these extremes are not normally experienced in the field because of snow cover. Although the study pond filled with runoff water by mid-April no change in the larval population structure occurred until mid-May. Emergence, which is highly synchronous, begins in the last week of May. However, it is governed by the prevailing air and water temperatures, and occurs only when the mean daily water temperature exceeds 12°C and the mean maximum air temperature reaches 20" to 21°C. Most insects emerge within 10 days of the first appearance of the adults. Sexual maturation takes about 1 week. Oviposition occurs while the pair are in tandem. Preferred oviposition sites are the submerged portions of stalks of floating plants such as Utricularia, Ranunculus, and Potamogeton. The observations are discussed in terms of the species' ability to survive the climatic extremes of central Canada.

Section: Methodsmentioning

confidence: 99%

The Biology of Two Related Species of Coenagrionid Dragonflies (Odonata: Zygoptera) in Western Canada

Sawchyn

Gillott

1975

“…The beetles from the egg development and oviposition study were preserved for dissection in an aqueous solution of chloral hydrate, formaldehyde, and acetic acid (Weaver and Thomas 1956). Additional specimens for histology were preserved in Bouin's aqueous picroformal.…”

Section: Materials For Oocyte Stagingmentioning

confidence: 99%

REPRODUCTIVE BEHAVIOUR AND PHYSIOLOGY OFTENEBRIO MOLITOR(COLEOPTERA: TENEBRIONIDAE): II. EGG DEVELOPMENT AND OVIPOSITION IN YOUNG FEMALES AND THE EFFECTS OF MATING

Gerber¹

1975

Can. Ent. 107: 551-559 (1975) Virgin females of Tenebrio molitor L. initiate vitellogenesis about 2 days after the imaginal moult. During the first 6 days after the imaginal moult, each female with males matured on the average 41 eggs and each virgin matured 29 eggs. Stimuli associated with copulation and(or) insemination apparently are not required to initiate vitellogenesis, but do enhance the rate of oocyte maturation. Mated females lay their first eggs on the fourth day and virgin females about 1 day later. After the sixth day, mated females matured oocytes at about the same rate as before this time, whereas oocyte production is almost completely inhibited in virgins. Mated females also laid about 7.5 times as many eggs and accumulated an average of 40% fewer eggs in their reproductive systems than virgins. It is suggested that stimuli associated with copulation and(or) insemination enhance oviposition per se in mated females, that the accumulation of eggs in the reproductive systems slows further development of oocytes in virgins, and that the inhibition of vitellogenesis in virgins occurs at, or soon after, the time the first gonadotropic cycle is completed. A system for classifying stages of oocyte maturation in T . molitor is described.

“…The abdomens were preserved in an aqueous solution of chloral hydrate, formaldehyde, and acetic acid (Weaver and Thomas 1956). The relationship between egg development and the first calling was investigated in virgin females during the first three complete scotophases after emergence.…”

Section: Methodsmentioning

confidence: 99%

PHARPA, A NEW GENUS OF NEOTROPICAL AGATHIDINAE (HYMENOPTERA: BRACONIDAE) WITH A DISCUSSION OF PHYLOGENETIC RELATIONSHIPS

Sharkey¹

1986

Can. Enl. 118: 1221-1230 (1986) The effects of age, egg development, and mating on calling behavior of the bertha armyworm, Mamestra conjgurata Walker, were studied at 20°C, 60% RH, and a 16h L : 8-h D photoperiod. Most virgin females called and copulated for the first time during the second or third scotophase after emergence. The first copulation was 17.0 ? 0.2 h (mean? SE) long and was terminated within 1 h after lights off in the scotophase following the initiation of copulation. The ovaries contained the first chorionated eggs before the beginning of the second scotophase after emergence. The first egg laying occurred during the same scotophase in which the first copulation was terminated, i.e. scotophase three or four. Almost 75% of the eggs were laid by the end of the seventh scotophase after emergence. Mated females resumed calling after a refractory period of about 2 days. Once calling was resumed after copulation, most females laid eggs and called nightly, with egg laying occurring during the first 5-6 h and calling during the last 2-3 h of the scotophase. Mated females called for a shorter period during each scotophase than virgin females of the same age (1-3 h vs. 4-6 h). In virgin females, the die1 periodicity of calling was advanced and the length of the daily calling period was increased with age until the seventh scotophase after emergence; thereafter, both remained relatively unchanged. ResumeLes effets de l'Lge, du dCveloppement des oeufs et de l'accouplement sur le comportement d'appel sexuel de la lkgionnaire bertha, Mamestra conjgurata Walker, ont Ct C etudits k 20°C, 60% d'humiditC relative et une photophiode de 16 h d'eclairement et de 8 h d'obscuritC. La plupart des femelles vierges ont appelC et copulC pour la premiere fois au cours de la deuxieme ou troisikme scotophase apres 1'Cmergence. La premikre copulation a durC 17,0?0,2 h (moyenne ? erreur-type) et s'est terminte dans les 60 min apres la mise k I'obscuritC dans la scotophase suivant le dCbut de la copulation. Les ovaires contenaient les premiers oeufs chorionCs avant le dCbut de la deuxieme scotophase aprks 1'Cmergence. La premiere ponte a eu lieu au cours de la m&me scotophase dans laquelle la premikre copulation s'est terminte, c'est-i-dire la troisikme ou la quatrieme. Pres de 75% des oeufs ont Ct C pondus avant la fin de la septikme scotophase aprks 1'Cmergence. Les femelles accouplCes se sont remises B l'appel sexuel aprks une pCriode refractaire d'environ 2 jours. A la reprise de I'appel aprks la copulation, la plupart des femelles ont pondu et ont fait l'appel de nuit, la ponte se produisant au cours des 5-6 premieres heures, et l'appel, au cours des 2-3 dernikres heures de la scotophase. Les femelles accoupltes ont appelC pendant une #node plus breve de chaque scotophase que les femelles vierges du meme Lge (1-3 h contre 4-6 h). Chez les femelles vierges, la pkriodicitk quotidienne de l'appel a Ct C devancCe et la durCe de l'appel quotidien s'est accrue avec 1'Lge jusqu'k la septitme scotophase aprks 1'Cmergence, ces de...