Left Antennae Research Articles

A CASE OF TERATOLOGY IN AMBLYTHYREUS POTANINAE (BIANCHI, 1899) (HEMIPTERA: REDUVIIDAE: PHYMATINAE) FROM CHINA

An abnormal male adult of an ambush bug species, Amblythyreus potaninae (Bianchi, 1899), from Yunnan Province of China is described. Antennae are asymmetrical with right antenna 2-segmented and left antenna 3-segmented (4-segmented in normal). Rostrum one-segmented (3-segmented in normal). Pronotum is slightly asymmetrical with left anterior angle rounded and right anterior acutely pointed. Right protibia is about 4/5 of normal in length. Right meso- and metatibiae curved and about 1/3 length of normal, with tarsi and pretarsi absent. All deformed parts of A. potaninae are illustrated and the scanning electron microscopic photos of the abnormal and normal left antennae are provided.

Mechanisms underlying the production of carapace vibrations and associated waterborne sounds in the American lobster,Homarus americanus

American lobsters produce carapace vibrations, which also lead to waterborne acoustic signals, by simultaneously contracting the antagonistic remotor and promotor muscles located at the base of the second antenna. These vibrations have a mean frequency of 183.1 Hz (range 87-261 Hz), range in duration from 68 to 1720 ms (mean 277.1 ms) and lead to waterborne sounds of similar frequencies. Lobsters most often produce these signals using only one pair of muscles at a time and alternate between the muscles of the left and right antennae when making a series of vibrations. Occasionally, they vibrate their carapace by simultaneously contracting both sets of muscles. While the remotor muscle is required for producing carapace vibrations, the promotor appears to play a secondary role. Electrical stimulation of the remotor, but not the promotor, results in the production of vibrations, while lesions of the remotor, but not promotor, eliminate the ability of lobsters to vibrate their carapace. Lobsters of all sizes and both sexes produce these signals when startled, grasped or threatened. However, at this time, the behavioral significance of vibration and/or sound production by American lobsters is not known.

Características morfométricas de Talitroides topitotum (Burt) (Crustacea, Amphipoda, Talitridae) na Serra do Mar, Guaratuba, Paraná, Brasil

Um estudo sobre as relações morfométricas entre o comprimento cefálico (Lc) e o comprimento total do corpo (Lt), e o número de artículos do flagelo do primeiro e segundo pares de antenas e o comprimento total do corpo foi realizado em uma população de Talitroides topitotum (Burt, 1934), no entorno da Usina Hidroelétrica de Guaricana, Guaratuba, Paraná. O objetivo foi auxiliar na inferência do comprimento do corpo a partir do comprimento cefálico e da idade relativa dos exemplares pela contagem do número de artículos de seus flagelos antenais. Um total de 975 exemplares foi coletado e fotografado, dos quais os artículos dos flagelos direito e esquerdo das antenas 1 e 2 foram contados e os comprimentos do segmento cefálico e do corpo foram medidos. Houve uma correlação linear entre o comprimento do segmento cefálico e o comprimento total do corpo definido pela equação Lc = 0,0506Lt + 0,3297; r² = 0,9577. Diferenças significativas foram observadas entre os números de artículos dos flagelos direito e esquerdo de ambas as antenas. A diferença foi de até quatro artículos no primeiro par de antenas e de doze no segundo. O maior número de artículos entre os dois flagelos mostrou uma correlação com a distribuição das classes de comprimento total do corpo com a equação a1 = 4,3463Lt0,4264 para o primeiro par de antenas, e a2 = 10,5700Lt0,3581 para o segundo par. Foi possível inferir o estágio relativo de desenvolvimento de T. topitotum pelas medidas do comprimento do segmento cefálico. Entretanto, somente o maior número de artículos entre os flagelos direito e esquerdo constitui parâmetro de referência para inferir a idade relativa dos indivíduos desta espécie.

Abundance and Developmental Stability ofPterostichus melanarius(Coleoptera: Carabidae) in Organic and Integrated Pest Management Orchards of Québec, Canada

This study evaluated the agricultural impacts of organic and integrated pest management (IPM) orchards in Quebec, Canada on the carabids Pterostichus melanarius Illiger (Coleoptera, Carabidae), with two biomonitors, population density and fluctuating asymmetry (FA) of morphologic and meristic characters. The carabids were trapped between May and August 1999 and 2000 in 20 pitfall traps on four organically certified orchards and five IPM farmlands located in two farming communities 100 km apart. Numbers of P. melanarius and total trap catch were assessed for each year. We measured the length of two segments of the right and left antennae, the length of first tarsae, and the number of tibiae spines on the mesothoracic leg of 50–100 individuals per site/yr. These measurements were used to calculate two fluctuating asymmetry indices to evaluate individual developmental stability. No differences in fluctuating asymmetry were found between organic and IPM orchards although total catch of P. melanarius was higher in IPM orchards in 1999. The use of fluctuating asymmetry analysis in these fields seem inadequate to assess the impact of pesticides. Density analysis give a slightly response in the opposite of the predictions because IPM orchards seem to be a more adequate habitat for this carabid species. There is a need for evaluating the impacts of natural products used in the organic cultures.

A Statistical Study of Regeneration in Two Species of Crustacea

ABSTRACT The material for this study consists of over 1900 camera lucida tracings of regenerated antennae of the two Cladoceran genera, Simocephalus and Daphnia, in all of which measurements of the regenerated parts were made. In about a thousand more examination was confined to the number of setae regenerated. The standard operation consisted of the amputation of the dorsal branch of the right antenna (in some experiments, of both antennae) through the second segment (Daphnia) or third (Simocephalus), thus removing four setae in both genera, together with two and a half segments of the antennar axis in Daphnia, and one and a half in Simocephalus. The missing segments are never regenerated, but a variable number of setae are produced in place of the four removed by the operation. The setae have a fairly complicated structure. The degree of regeneration was chiefly measured by the number and length of setae regenerated. The effect of varying the segment of amputation, or level of amputation within a segment, is described. The vigour of regeneration shows no decline with age (at any rate, from late embryo to first adult instar). The regeneration of one antenna is not affected, either favourably or unfavourably, by the simultaneous regeneration of the other. No “improvement with practice” takes place. The regeneration of one antenna is either unaffected, or adversely affected, by the previous regeneration of the other. Within the wide limits tested, the state of nutrition of the animal has no influence on regeneration. The general internal condition of the animal, within the limits of variation dealt with, has very little influence on regeneration, as shown by the absence or low degree of correlation between the regeneration of right and left antennae of the same animal. The general complex of external conditions exerts a significant influence on regeneration. The main cause of variation in degree of regeneration is to be looked for in very numerous small factors localised in the regeneration blastem. The combined action of all these factors determines the regeneration potential. The value of this varies approximately according to the normal probability distribution, and expresses itself primarily in the number of setae produced. The left-hand end of the distribution of seta number resulting from the distribution of potential is cut off owing to the fact that the potential must rise beyond a certain threshold value before any setae can be produced. The distribution is condensed at the righthand end owing to a tendency for the formation of new setae to cease when four have been formed. Owing to the failure to regenerate the missing segments of the antennar axis, the formation of new setae after amputation near the base of the antenna only very imperfectly restores the original condition. When the amputation is performed through the apical segment, however, the regeneration of the setae removed by the operation practically restores the antenna to its original state. It is suggested that this is connected with the fact that after amputation near the base of the antenna, regeneration is highly variable and indeterminate, new setae being added to the regenerate throughout life; whereas after operation through the apical segment regeneration generally consists in the formation of the proper number of setae and then stops.