The contribution of prehatch and posthatch development to protandry in the chrysomelid, Diabrotica virgifera virgifera

Abstract

Laboratory tests with eggs of Diabrotica virgifera virgifera LeConte showed that during a 10‐day hatching period, hatch of male eggs predominated on the first and second days, eggs of mixed sex, with ca. 1:1 ratio, hatched on the third and fourth days, and eggs hatching from the fifth to the tenth days were nearly all female. Overall, female eggs hatched a mean of 2.9 days later than male eggs. Not only did female eggs hatch later, but the time for posthatch development to the adult stage was 1.8 days longer for females. The later egg hatch and longer posthatch development for females resulted in female adults emerging a mean of 4.7 days later than male adults. Total adult emergence lasted 14 days; of this, males predominated during the first 5 days, and females predominated during the last 9 days. Males of D. v. virgifera appear to have evolved protandry (the tendency for males to emerge before females) by developing both a postdiapause embryonic stage and a combined larval and pupal stage of shorter duration. RÉSUMÉ Contribution à la protandrie des périodes précédant ou suivant l'éclosion des oeufs de Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). L'observation, au laboratoire, pendant une période d'éclosion de dix jours, des oeufs de D. v. virgifera LeConte, a montré que les oeufs mâles prédominent les deux premiers jours d'éclosion, que les oeufs des deux sexes, avec des fréquences 0,5/0,5, ont éclos les troisième et quatrième jours, et que les oeufs éclos du cinquième au dixième jour étaient presque tous femelles. Globalement, les oeufs femelles ont éclos en moyenne 2,9 jours plus tard que les oeufs mâles. De plus, la durée du développement post‐embryonnaire des femelles a demandé 1,8 jour en plus. Une éclosion plus tardive et un développement post‐embryonnaire plus long ont entrainé une émergence des femelles en moyenne 4,7 jours après les mâles. La période d'émergence des adultes s'est étalée sur 14 jours; les mâles ayant dominé pendant les 5 premiers jours et les femelles pendant les 9 derniers. Les mâles de D. v. virgifera semblent avoir évolué vers la protandrie en acquerant, tant une diapause post‐embryonnaire que des Stades de développements larvaire et nymphal plus brefs.

Interactions Among Bt Maize, Entomopathogens, and Rootworm Species (Coleoptera: Chrysomelidae) in the Field: Effects on Survival, Yield, and Root Injury

“…3), consistent with Þeld data from other studies (Storer et al 2006, Murphy et al 2010, Hibbard et al 2011. Western corn rootworm is protandrous, with females emerging later than males (Branson 1987). The reason for earlier average emergence dates for male northern corn rootworm in pathogen-treated plots is unknown.…”

Evaluation of <I>Cuphea</I> as a Rotation Crop for Control of Western Corn Rootworm (Coleoptera: Chrysomelidae)

“…1). Beetle emergence from plots planted to corn followed expected trends with peak emergence of males preceding peak emergence of females (Kuhlman et al 1970, Branson 1987, Jackson and Elliott 1988. Also, peak beetle emergence in corn plots occurred in July as expected.…”

Corn rootworms (Coleoptera: Chrysomelidae) in space and time

“…Western com rootworms emerge a few days earlier than northern com rootworms (Ruppel et al 1978, Branson 1987) and males of both species develop faster than females (Jackson andElliott 1988, Nowatzki et al 2002). Adults feed on pollen and silks and mate in the cornfield soon after emergence (Branson 1987). A preovipositional period lasts 12 to 14 days (Hill 1975) and mean fecundity for the western com rootworm in the laboratory is ca.…”