Separation of Psychodopygus carrerai carrerai and P. yucumensis (Diptera: Psychodidae) by gas chromatography of cuticular hydrocarbons

The Lutzomyia longipalpis complex: a brief natural history of aggregation-sex pheromone communication

In this paper we review the natural history of pheromone communication and the current diversity of aggregation-sex pheromones in the sand fly Lutzomyia longipalpis. This species complex is the main vector of Leishmania infantum, the agent of visceral leishmaniasis in the Americas. The identification of variation in pheromone chemotypes combined with molecular and sound analyses have all contributed to our understanding of the extent of divergence among cryptic members of this complex. The importance of chemical signals as pre-mating barriers and drivers of speciation is discussed. Moreover, the importance of aggregation-sex pheromones as sexually selected signals is highlighted with evidence from the literature suggesting their potential role in species and mate recognition as well as mate assessment. The distinct evolutionary forces possibly involved are briefly reviewed and discussed in the context of this intriguing insect.

Multivariate morphometric discrimination among three species of Lutzomyia subgenus Micropygomyia (Diptera: Psychodidae)

Canonical discriminant analysis accurately separated males of Lutzomyia yencanensis (n = 36) (Ortiz), Lutzomyia cayennensis cayennensis (n = 24) (Floch and Abonnenc) and Lutzomyia micropyga (n = 28) (Mangabeira). Only seven (length of head, interocular distance, wing vein delta, genital filaments, coxite, paramere, and lateral lobe) of 20 possible morphometric measurements were required for differentiation, with a highly significant canonical correlation. The discriminant equations provided a simple, fast, and widely available statistical tool to identify accurately unknown sand fly specimens as L. yencanensis, L. c. cayennensis, or L. micropyga.

Cuticular hydrocarbon discrimination/variation among strains of the mosquito, Anopheles (Cellia) stephensi Liston

Cuticular lipids were removed from adult female Anopheles stephensi Liston and the hydrocarbons present were separated and quantified by gas chromatography. Comparison was made between the hydrocarbons of four An. stephensi strains: Russ, sensitive to DDT and malathion and originally isolated in the former U.S.S.R.; Beech, a DDT-resistant Indian strain with high sensitivity to Plasmodium species; St Mal, a strain from Pakistan shown to be resistant to malathion; and Iraq, a DDT-susceptible strain from Iraq. Discriminant analysis indicated that the four groups were distinct and that, on average, 78% of the population could be separated on the basis of the quantities of some of the cuticular hydrocarbons. The profiles of Beech and Russ or Russ and St Mal could be separated in 98% of the cases. There was reduced segregation between the profiles of St. Mal and Iraq, suggesting greater similarity in the hydrocarbons of these two strains. The usefulness of cuticular hydrocarbon in determining species relationships is discussed.

A Chemotaxonomic Study of Cuticular Hydrocarbons on Epilachna indica (Family: Coccinellidae) from Sarawak

The chemical composition of cuticular hydrocarbons of adult Epilacnha indica (ladybird beetles), collected fromKota Samarahan, Kota Padawan and Lanjak-Entimau, Sarawak were analyzed by using a capillary gaschromatography-mass spectrometer (GC-MS). Cuticular hydrocarbons extracted from 18 samples of adult E.indica (comprise of 90 individuals). Over 95% of the hydrocarbon peak areas consist of chain lengths from C18to C38 . The proportions of n-alkanes between three different localities are significantly difference, except for ndotriacontaneand n-tetratriacontane. Comparison between Kota Samarahan and Kota Padawan samples revealedthe significant different in hydrocarbon composition for even-numbered carbon n-alkanes ranging from n-C18 ton-C38 except for n-C32 and n-C34 . Several odd-numbered carbon n-alkanes such as n-C25 , n-C27 , n-C33 and n-C35 also showed significant difference in the composition between Kota Samarahan and Kota Padawan.Examination on components contributing to the differentiation of localities showed that n-C29 , n-C33 and n-C36were important in discriminating three different localities. Discriminant function analysis (DFA) successfullyclassified all samples into three correct groups in 100% of cases, with cross-validation resulted in an error of7.7%. Individuals from each locality were grouped in the range of 2.10 - 9.16% differences, with average of43% different reflected between localities. E. indica samples collected from the forests containing simplerhydrocarbon pattern than samples collected around housing or industrial areas. Result showed that differences inmicroenvironment have influenced the composition and proportion of insect cuticular hydrocarbon. The findingreveals the potential of cuticular hydrocarbons profile to separate subpopulations of species.