Abdominal Color Pattern Research Articles

Phenotypic plasticity in hoverflies: the relationship between colour pattern and season in Episyrphus balteatus and other Syrphidae

1. The abdominal colour patterns of some multivoltine species of hoverfly are phenotypically plastic and change through the flying season. 2. It was predicted how the abdominal colour pattern of one species, Episyrphus balteatus, should change in the field with season based on a hypothesis that the pattern influences the thermoregulatory capabilities of the animal. The colour patterns were quantified using image analysis. The observed changes in the colour pattern through the year supported the thermoregulation hypothesis. 3. A further three Metasyrphus species were analysed similarly to allow a comparative study of the forms of the plasticities of the above four species and four Eristalis species from a previous study. 4. Whilst it was clear that the abdominal colour patterns of many of the species were plastic, it was also apparent that not all species used the same developmental pathway to control the seasonal colour pattern changes. This suggests convergent evolution towards a general type of plasticity and that abdominal colour pattern plasticity in hoverflies is functional.

The genetics of phenotypic plasticity in adult abdominal colour pattern of Eristalis arbustorum (Diptera: Syrphidae)

The abdominal colour pattern of Eristalis arbustorum is a plastic character which is heavily influenced by developmental temperature. The present study investigated the form of the reaction norms of amount of abdominal yellow and intensity of the yellow (measured as grey value) on pupal development temperature. The slope of the reaction norm for amount of yellow was steeper in males than in females. The reaction norms for grey value on temperature were nonlinear. Family groups were reared to enable a consideration of the genetics to be made. There were significant family by environment interactions for both characters for both sexes indicating genetic variance for plasticity. Pupal development time is closely correlated with developmental temperature. The relationship between amount of yellow on the abdomen and log pupal development time was curvilinear and fitted a quadratic function well. There was significant among-family variation in the slopes of these lines for females, but not for males, again suggesting genetic variation for plasticity. The results are discussed in relation to the maintenance of genetic variation.

The influence of the development rates of immature stages of Eristalis arbustorum (Diptera; Syrphidae) on adult abdominal colour pattern

Abstract. The abdominal colour pattern of Eristalis arbustorum (L.) shows seasonal variation, with animals emerging in spring being darker than those emerging during summer. One of the most important environmental cues influencing the abdominal colour pattern is developmental temperature. An experiment was carried out to establish which period during the immature stages was important in determining final adult colour pattern. The results indicate a good relationship between the length of the pupal period and both the extent of the paler markings on the abdomen and the grey score of these markings. The length of the larval period did not have any effect on adult colour pattern.

What makes a happy face? Determinants of colour pattern in the Hawaiian happy face spider Theridion grallator (Araneae, Theridiidae)

Theridion grallator, a small (<5 mm) spider endemic to wet and mesic forests of Hawaii, is highly polymorphic in its abdominal colour pattern. Morphs were either translucent yellow (the background colour only; no pattern) or exhibited superimposed pigmentation. These latter, patterned morphs were grouped into eight major categories, including opaque white and various configurations of red, black or maroon. The unpatterned morph was the most morph common among immatures (69 per cent), mature males (62 per cent) and mature females (62 per cent). All spiderlings were initially unpatterned; patterns developed at 10 to > 100 days after hatching. Time required for completion of pattern development was roughly proportional to the amount of red in the final pattern. Mature males and females had similar morph frequencies overall, yet three rare morphs were seen only in females. Phenotypic frequencies of families were consistent with Mendelian inheritance at one locus, with the allele dictating absence of pattern recessive to alleles for patterned morphs.

A New Species of Macrothemis from Central America with Notes on the Distinction between Brechmorhoga and Macrothemis (Odonata: Libellulidae)

Macrothemis aurimaculata, a new species from Guatemala and Costa Rica, is closely related to M. inequiunguis (Calvert), but differs in abdominal color pattern, shape of superior appendage and posterior hamule of the male, and color of the frons. The two species differ from other Macrothemis in the shorter tooth of the tarsal claw. The most constant distinction between Macrothemis and Brechmorhoga is the narrowed discoidal field in the front wing in Macrothemis.

Observations on the Mosquito, Aëdes (Stegomyia) aegypti (L.), in East Africa. II.—The Biting Cycle in a Domestic Population on the Kenya Coast

Since the sharply defined biting cycle shown by outdoor populations, in Uganda, of Aëdes aegypti (L.), which closely resembles oviposition and general activity rhythms, could not be reconciled with the ill-defined patterns found in domestic populations, on the Kenya coast, in the absence of knowledge of the composition of the population involved there, 24-hour baited catches were made at Ganda on the Kenya coast, and the abdominal colour pattern of each individual was noted. In the series there was gradation from the darkest to the palest.Of 427 females taken biting, 82·1 per cent, were of var. queenslandensis (Theo.) in the generally accepted sense, 14·5 per cent, of the type form and 0·9 per cent, of subsp. formosus (Wlk.). The material of var. queenslandensis was further divided into two groups in which the lateral spots on the abdominal tergites were of silver and matt white scales, respectively.Very similar biting cycles, with the main peak in the hour before sunset, occurred both inside a hut and within an adjacent compound, although catches were not concurrent and were made under different seasonal conditions.The distribution of the various colour forms in the total catch was independent of the hour of capture.There is a resemblance between these cycles and those reported in comparable situations in Nigeria, where, with the exception of the paler forms, the population of A. aegypti is similar to that at Ganda. It is concluded that the main biting peak is shortly before sunset. Subsidiary peaks, when present, occur with increasing intensity as the day progresses.The relationship of biting activity to other aspects of general activity is discussed, and it is concluded that several aspects require further investigation.The following hypothesis is offered to account for the various patterns of biting cycle observed in different situations. It is suggested that A. aegypti possesses an endogenous multi-peaked diel rhythm of activity. Activity impulses occur in a cycle of waves of increasing intensity from dawn onwards, reaching a maximum at the end of the daylight period, and a biting peak will result when such an impulse coincides with environmental conditions within the range between upper and lower thresholds of activity.