Immature stages of Utetes anastrephae (Hymenoptera: Braconidae) developed in Anastrepha fruit fly larvae (Diptera: Tephritidae).

The morphology of the immature stages of Utetes anastrephae (Hymenoptera: Braconidae), a native parasitoid of larvae of flies of the Neotropical genus Anastrepha (Diptera: Tephritidae), is shown. This study aimed to characterize the immature stages and morphological changes in the development of the koinobiont endoparasitoid in two species of larval hosts, Anastrepha obliqua and Anastrepha ludens. The definition of structures and morphological changes during development was made through daily microscopic observations and photographs of dissected hosts. The immature development of the parasitoid corresponds to a holometabolous insect with three well-defined stages: egg (two days), larva with three larval instars (approximately eight days), and pupa (six days). Similar development times were obtained in the two host species. Males and females completed their cycle in 17 and 18 days, respectively. During egg-first instar development, host antagonistic activity through melanization and encapsulation as mortality factors was evident and frequent only in A. obliqua. These results serve as basic knowledge for the use of this parasitoid in the biological control of fruit flies.

Aedes aegypti, Ae. albopictus and Culex quinquefasciatus Adults Found Coexisting in Urban and Semiurban Dwellings of Southern Chiapas, Mexico.

Tapachula, Mexico, a tropical city, is an endemic area for dengue, in addition to several outbreaks in the last decade with chikungunya and zika. As part of the migratory corridor from Central to North America and the risks of scattered infectious diseases that this implies, the identification and distribution of potential disease vectors in and around residential areas are essential in terms of entomological surveillance for the prevention of disease outbreaks. The identification of mosquito species of medical importance coexisting in houses and cemeteries in Tapachula and two semiurban sites in southern Chiapas was investigated. Adult mosquitoes were collected from May to December 2018, resting inside and outside houses and in the tombstones and fallen tree leaves in cemeteries. A total of 10,883 mosquitoes belonging to three vector species were collected across 20 sites; 6738 were from neighborhood houses, of which 55.4% were Culex quinquefasciatus, 41.6% Aedes aegypti, and 2.9% Ae. albopictus. Aedes aegypti was the most common mosquito resting inside houses (56.7%), while Ae. albopictus and Cx. quinquefasciatus were mostly found resting outside houses (75.7%). In the cemeteries, Cx. quinquefasciatus (60.8%) and Ae. albopictus (37.3%) were the most abundant, while Ae. aegypti (1.9%) was the least abundant. This is the first report to identify adults of three major disease vector species coexisting in the domestic environment of urban and semiurban sites and Ae. albopictus adult resting inside of urban houses in Mexico. It would be opportune to consider comprehensive strategies that can be applied in this region to control the three species at the same time and avoid outbreaks of the diseases they transmit.

Current enzyme-mediated insecticide resistance status of Aedes aegypti populations from a dengue-endemic city in southern Mexico.

OBJECTIVE: To identify the enzyme-mediated insecticide resistance in Aedes aegypti in Tapachula, Mexico. MATERIALS AND METHODS: Biochemical assays were undertaken to determine the enzyme levels in mosquitoes from 22 sites collected in 2018 and 2020 in Tapachula. Results of 2018 were correlated with the resistance to insecticides pub-lished. RESULTS: Mosquitoes had higher levels than those of the susceptible strain in 2018 and 2020 respectively of α-esterases in 15 and 12 sites; ß-esterases in 7 and 6 sites; glutathione-S-transferases in 11 and 19 sites; ρNPA-esterases in 21 and 17 sites; and cytochromes P450 in 20 and 22 sites. In mosquitoes of 2018, there was a moderate correlation between previously documented Malathion resistance ratios and the insensitive acetylcholinesterase (r=0.459, p= 0.03). CONCLUSIONS: The elevated enzyme levels found indicate its contribution to the resistance to pyrethroids and organo-phosphates already published in mosquitoes from Tapachula. Bioassays using enzyme inhibitors resulted in greater mor-tality, confirming that metabolism contributes to resistance.

Does body size influence mating success? A morphometric study of two Anastrepha (Diptera: Tephritidae) fruit fly species.

Male mating success depends on various traits and factors, and correctly identifying these traits can be key in the context of pest management. For tephritid pests, controlled through the sterile insect technique (SIT) traits, such as male size, can be manipulated through mass-rearing procedures. Thus, it is particularly important to understand whether male size can favor mating success. Here, we evaluated mating success of males of different sizes in Anastrepha ludens and Anastrepha obliqua, two species controlled through SIT. For both species, a morphometric analysis was performed of mated and unmated mass-reared and wild males in field cages. In both A. ludens and A. obliqua, wild females did not discriminate their mates based on male size and mated more frequently with wild males regardless of size. For mass-reared males, we found no evidence of an advantage of the large males compared to small males in mating success. However, we did find differences between the morphometric traits of mass-reared and wild males. In A. ludens, traits associated to mating success were Face Width (FW), Head Width (HW), Thorax Length (TL) and Wing Length (WL), and for A. obliqua were FW, HW, WL and WW (Wing Width). Overall, FW and TL were more consistent predictors of mating success. In conclusion, female choice seems to suggest multivariate selection, confirming that overall body size (expressed as pupal diameter, which is highly correlated with weight) is not a decisive factor in male mating success in these two species. However, morphological traits such as FW, HW, TL, WL and WW may be relevant in mating preference of wild female.

Differences in volatile composition and sexual morphs in rambutan (Nephelium lappaceum L.) flowers and their effect in the Apis mellifera L. (Hymenoptera, Apidae) attraction

ABSTRACT We studied the volatile composition and sexual morphs of Nephelium lappaceum flowers from two orchards, and investigated the choice behavior of the honey bee, Apis mellifera toward the floral extracts from both locations. Our results showed significant differences in chemical composition and sexual morphs; only the hermaphrodite flowers from the Herradero orchard produced limonene and α-pinene and had longer peduncle and sepal than flowers from the Metapa orchard; on the other hand, the hermaphrodite flowers from the Metapa orchard had longer gynoecium. In the behavioral experiment the extracts from the Herradero orchard seemed to give A. mellifera foragers better cues for orientation to food sources, perhaps due to the presence of limonene and α-pinene, which are absent in the samples from Metapa. Such differences in both orchards could affect pollinator attraction and ultimately seed set and productivity.

The Stingless Bee Melipona solani Deposits a Signature Mixture and Methyl Oleate to Mark Valuable Food Sources.

Stingless bees foraging for food improve recruitment by depositing chemical cues on valuable food sites or pheromone marks on vegetation. Using gas chromatography/mass spectrometry and bioassays, we showed that Melipona solani foragers leave a mixture composed mostly of long chain hydrocarbons from their abdominal cuticle plus methyl oleate from the labial gland as a scent mark on rich food sites. The composition of hydrocarbons was highly variable among individuals and varied in proportions, depending on the body part. A wide ratio of compounds present in different body parts of the bees elicited electroantennogram responses from foragers and these responses were dose dependent. Generally, in bioassays, these bees prefer to visit previously visited feeders and feeders marked with extracts from any body part of conspecifics. The mean number of visits to a feeder was enhanced when synthetic methyl oleate was added. We propose that this could be a case of multi-source odor marking, in which hydrocarbons, found in large abundance, act as a signature mixture with attraction enhanced through deposition of methyl oleate, which may indicate a rich food source.

Effect of Citrus floral extracts on the foraging behavior of the stingless bee Scaptotrigona pectoralis (Dalla Torre)

Effect of Citrus floral extracts on the foraging behavior of the stingless bee Scaptotrigona pectoralis (Dalla Torre). Stingless bees have an important role as pollinators of many wild and cultivated plant species in tropical regions. Little is known, however, about the interaction between floral fragrances and the foraging behavior of meliponine species. Thus we investigated the chemical composition of the extracts of citric (lemon and orange) flowers and their effects on the foraging behavior of the stingless bee Scaptotrigona pectoralis. We found that each type of flower has its own specific blend of major compounds: limonene (62.9%) for lemon flowers, and farnesol (26.5%), (E)-nerolidol (20.8%), and linalool (12.7%) for orange flowers. In the foraging experiments the S. pectoralis workers were able to use the flower extracts to orient to the food source, overlooking plates baited with hexane only. However, orange flower extracts were seemingly more attractive to these worker bees, maybe because of the particular blend present in it. Our results reveal that these fragrances are very attractive to S. pectoralis, so we can infer that within citric orchards they could be important visitors in the study area; however habitat destruction, overuse of pesticides and the competitive override by managed honeybees might have put at risk their populations and thus the ecological services they provide to us.

Extratos florais de Citrus no comportamento de forrageamento da abelha sem ferrão Scaptotrigona pectoralis (Dalla Torre). As abelhas sem ferrão têm um papel importante na polinização de muitas espécies de plantas nativas e plantas cultivadas em regiões tropicais. Pouco se sabe, no entanto, sobre a interação entre as fragrâncias florais e comportamento de forrageamento de espécies de meliponíneos. Assim, investigou-se a composição química dos extratos de cítricos florais (limão e laranja) e seus efeitos sobre o comportamento de forrageamento da abelha sem ferrão Scaptotrigona pectoralis. Nós descobrimos que cada tipo de flor tem a sua própria composição específica de mistura de compostos: limoneno (62,9%), e farnesol (26,5%) para flores de limão, (E)-nerolidol (20,8%), e linalol (12,7%) para flores de laranja. Nos experimentos de forrageamento, as operárias de S. pectoralis foram capazes de utilizar os extratos de flores para se orientarem até a fonte de alimento, não sendo atrapalhadas por placas com iscas apenas de hexano. No entanto, os extratos de flores de laranja foram aparentemente mais atraentes para essas abelhas operárias, talvez por causa da mistura particular do extrato. Nossos resultados revelam que essas fragrâncias são muito atraentes para S. pectoralis, assim pode-se inferir que dentro de pomares cítricos poderiam ser visitantes importantes na área de estudo; no entanto a destruição do habitat, o uso excessivo de pesticidas e a substituição competitiva por abelhas Apis poderia por em risco suas populações e, assim, os serviços ecológicos que prestam para nós.