Age‐specific flight behavior in relation to body weight and lipid content of Ips calligraphus reared in slash pine bolts with thick or thin inner bark (phloem)

Abstract

Rearing larvae of Ips calligraphus (Germar) (Coleoptera: Scolytidae) in bolts of typical slash pine, Pinus elliottii Engelm. var. elliottii, with ‘thin’ (TN; 0.5–1.5 mm) phloem (inner bark) relative to adult beetle body width significantly reduced body weight and lipid content of emerging adults compared with ‘thick’ (TK; 2.5–3.5 mm) phloem‐reared adults. Unmated (pre‐nuptial) TK beetles averaged 2‐fold longer daily and lifetime flight duration than TN beetles. Daily flights were highly variable, averaging < 20 min (longest daily flight = 173 min). TK and TN beetles initiated flight, and the greatest number flew, on the first or second day after emergence from their rearing bolt % of beetles flying and survival gradually declined to zero by day 9. Males (both TK and TN) averaged 2.5 days of flight, ca. 1 day longer than females. Fliers lived ca. 2‐fold longer than non‐fliers. Among TK and TN fliers, significant but weak positive correlations occurred between body weight and lifetime flight duration. Poor correlation between lifetime flight duration and longevity suggests little physiological cost to flight, but effects on fecundity were not assessed. Flight by mated, egg‐laying (post‐nuptial) beetles was substantially delayed (peaking on day 6), suggesting degeneration and subsequent regeneration of flight muscles. Résumé Comportement de vol d'Ips calligraphus élevé sur Pinus elliottii au phloem plus ou moins épais; relations avec l'âge, le poids et la teneur en lipides Le comportement de vol d'Ips calligraphus GERMAR (Scolytidae) a été examiné au laboratoire par une technique de vol captif. La génération parentale avait été artificiellement introduite, suivant la taille des adultes (1,6 à 2,1 mm) dans des morceaux de Pinus elliottii Engelm. variété elliottii au phloeme épais (TK = 2,5 à 3,5 mm) ou fin (TN = 0,5 à 1,5 mm) les larves se sont développées dans ces morceaux de pin. Le poids et la teneur en lipide des adultes obtenus à partir de TN étaient sig‐nificativement inférieure à ceux de TK. Le poids des mâles les plus gros a été plus réduit que celui des femelles; les mâles les plus petits semblaient être moins efficaces dans l'initiation des attaques sur les arbres, et les femelles les plus petites ont eu une fécondité réduite. Les durées de vol quotidiennes pendant la vie des mâles TK vierges étaient en moyenne deux fois plus longues que celles des mâles TN. Les durées de vol quotidiennes étaient très variables: en moyenne moins de 20 minutes, mais la plus longue a été de 173 mn. En moyennes les adultes TN et TK ont commencé à voler, et volaient en plus grand nombre, le premier et le second jour après l'émergence. Ensuite la fréquence d'adultes volants et le pourcentage de surviveants, ont graduellement diminué jusqu'à tomber à zéro le neuvième jour. Les mâles TN et TK avaient des vols quotidiens plus longs et volaient environ 1 jour de plus que les femelles. L'activité de vol accrue des mâles reflète leur besoin de trouver dans la nature des arbres convenables; les vols des femelles peuvent généra...

Effect of crowding, food deprivation, and diet on flight initiation and lipid reserves of the lesser grain borer, Rhyzopertha dominica

“…The same tendency also was reported with Ips calligraphus reared in slash pine bolts with thick or thin phloem (Slansky Jr. & Haack, 1986); insects reared in thick phloem produced individuals with greater lipid reserves and greater capacity for flight. Although adult body weights of beetles reared in the four types of grain were similar, the percentages of lipid for each population varied significantly.…”

Thinning of mature lodgepole pine stands increases scolytid bark beetle abundance and diversity

“…Since the two numerically dominant beetle species, striped ambrosia beetles and pine engravers, can cause economic damage to standing and felled trees, felled trees should be removed from the stands before the breeding season of these beetles. This caution is further warranted by the observation that trees that had been growing vigorously at the time of death, such as in thinned stands, are superior breeding habitat for secondary bark beetles (Slansky and Haack 1986;Reid and Robb 1999). More generally, this study prompts caution in the use of thinning as a management tool to control bark beetles.…”

Phoresy by Dendrochernes Pseudoscorpions on Cerambycidae (Coleoptera) and Aulacidae (Hymenoptera) in Florida

“…The failure to encounter phoretic pseudoscorpions on Ips calligraphus adults may be explained (a) by the similar weights of these two organisms (ca. 2-3 mg, dry wt, both sexes; Slansky and Haack, 1986); (b) by Ips adults serving as food rather than as phoretic hosts when encountered (pseudoscorpions are predators of "small" arthropods such as beetle larvae and adults; Weygoldt, 1969;Jones, 1978), and/or (c) by the odor of Ips adults not being attractive to pseudoscorpions. Phoretic cercomegistid, macrochelid and uropodid mites, which are much smaller than pseudoscorpions, were common on most adult Ips; Moser (1976) reported that live uropodid mites averaged 0.0064 mg each.…”