Negative Effects of the Neonicotinoid Clothianidin on Foraging Behavior and Antennal Sensitivity in Two Common Pollinator Species, Osmia bicornis and Bombus terrestris

Insect species richness and abundance has declined rapidly over the last few decades. Various stressors, such as the conversion of natural habitats, climate change, land-use intensification, agrochemicals and pathogens, are thought to be major factors in this decline. We treated female bees of two common pollinator species in Europe, Osmia bicornis and Bombus terrestris, with a field-realistic dose of the neonicotinoid clothianidin. We tested its effects on the foraging behavior of O. bicornis under semi-natural conditions and on the antennal sensitivity of both bee species to common floral volatiles by using electroantennography. Clothianidin negatively affected the foraging behavior in O. bicornis by decreasing the number of flowers visited per foraging flight and by increasing the time per flower visit and the searching time between two flowers. It also decreased the antennal sensitivity to 2-phenylethanol in the two bee species. Thus, clothianidin is clearly a threat for bees via its effects on their foraging behavior and antennal sensitivity and is hence probably detrimental for pollination and the reproductive success of bees.

Why are there not more herbivorous insect species?

Insect species richness is estimated to exceed three million species, of which roughly half is herbivorous. Despite the vast number of species and varied life histories, the proportion of herbivorous species among plant-consuming organisms is lower than it could be due to constraints that impose limits to their diversification. These include ecological factors, such as vague interspecific competition; anatomical and physiological limits, such as neural limits and inability of handling a wide range of plant allelochemicals; phylogenetic constraints, like niche conservatism; and most importantly, a low level of concerted genetic variation necessary to a phyletic conversion. It is suggested that diversification ultimately depends on what we call the intrinsic trend of diversification of the insect genome. In support of the above, we survey the major types of host-specificity, the mechanisms and constraints of host specialization, possible pathways of speciation, and hypotheses concerning insect diversification.

To us insectometers, it is clear that insect decline in our Costa Rican tropics is real, so let’s be kind to the survivors

We have been field observers of tropical insects on four continents and, since 1978, intense observers of caterpillars, their parasites, and their associates in the 1,260 km2 of dry, cloud, and rain forests of Área de Conservación Guanacaste (ACG) in northwestern Costa Rica. ACG’s natural ecosystem restoration began with its national park designation in 1971. As human biomonitors, or “insectometers,” we see that ACG’s insect species richness and density have gradually declined since the late 1970s, and more intensely since about 2005. The overarching perturbation is climate change. It has caused increasing ambient temperatures for all ecosystems; more erratic seasonal cues; reduced, erratic, and asynchronous rainfall; heated air masses sliding up the volcanoes and burning off the cloud forest; and dwindling biodiversity in all ACG terrestrial ecosystems. What then is the next step as climate change descends on ACG’s many small-scale successes in sustainable biodevelopment? Be kind to the survivors by stimulating and facilitating their owner societies to value them as legitimate members of a green sustainable nation. Encourage national bioliteracy, BioAlfa.

Macroinvertebrate Taxonomic Richness in Minimally Disturbed Streams on the Southeastern USA Coastal Plain

Collections made over 20 years with a multiple habitat sampling protocol and Hester–Dendy artificial substrate samplers were used to assess macroinvertebrate genera richness in first- to fourth-order streams on the Savannah River Site (SRS), a 780-km2, U.S. government reservation on the upper South Carolina, USA, coastal plain. We collected 312 genera representing 114 families including 268 genera and 87 families of insects. The total number of genera from each stream averaged 139 (97–194) with totals of 171–261 for drainages with more than one stream. Larger streams supported more macroinvertebrate genera, but small headwater streams supported genera not found in higher-order streams and contributed to drainage-wide richness. Sampling effort expressed as number of individuals collected or sites sampled and sampling duration influenced genera richness more than other factors. Genera accumulation curves showed that full representation of richness required several years of sampling and the inclusion of sampling sites that represented all habitats. Upper Three Runs, known for high insect species richness, was the most genera-rich stream, but richness was nearly comparable in other streams after adjusting for sampling effort. Some SRS streams are minimally exposed to anthropogenic disturbance, making them relatively unique in the southeastern USA Sand Hills and valuable as reference models.

Why species richness of plants and herbivorous insects do or do not correlate

Unraveling the determinants of herbivorous insect diversity has been a major challenge in ecology. Despite the strong association between insect and plant species, previous studies conducted in natural systems have shown great variation in the strength of the correlation between their species richness. Such variation can be attributed to the proportion of generalist insect species (generality), though both higher and lower generality may weaken the correlation because 1) generalist insect species are less dependent on the number of plant species and 2) specialist insect species utilize only a part of the total plant species. To explore these opposing effects, we studied plant and herbivorous insect communities in semi-natural grasslands in Japan. Plant–insect interactions were evaluated in a unique way with a particular focus on the staying and herbivory behaviors of insects, which reflect their habitat use as well as host use. We fousnd that generality of insect communities negatively affected the correlation between species richness of plants and insects. However, such negative effect was significant only when the insect species richness was related with the number of plant species interacted with some insect species, instead of with that of total plant species. The results suggest that considering either of the opposing effects of insect generality is insufficient and they should be inclusively interpreted to understand the relationship between plant and insect species richness.

A new species of Glyptapanteles Ashmead (Hymenoptera, Braconidae, Microgastrinae) within Macrobrochis gigas (Lepidoptera, Arctiidae, Lithosiidae) in Fujian, China

The south-east coastal area of Fujian, China, belongs to the Oriental Realm, and is characterized by a high insect species richness. In this work, a new species of Hymenopteran parasitoid, Glyptapanteles gigas Liang & Song, sp. nov. found in Jinjiang within hosts of caterpillars Macrobrochis gigas (Lepidoptera: Arctiidae), is described and illustrated, with differences from similar species. Additionally, we presumed that both parasitoid and host species play very important role in the coevolution and tritrophic interaction between plants, phytophagous insects, and their parasitoids, because these insects probably broke the sporangia and made contributions to their colonization, or some spores were spread for long distances by adult moths after their emergence, or some parasitoids were attracted by the eggs and larvae of these caterpillars, which was also thought to be helpful to spread of spores.

Correlation between some landscape metrics and insect species richness in coffee agroforests in Pangalengan Subdistrict, Bandung District, West Java, Indonesia

Withaningsih S, Parikesit, Rabbany MB. 2019. Correlation between some landscape metrics and insect species richness in coffee agroforests in Pangalengan Subdistrict, Bandung District, West Java, Indonesia. Biodiversitas 20: 3075-3085. The insect community provides valuable ecosystem services and can help maintain ecosystem integrity in human-altered landscapes such as coffee agroforests. The aim of this study was to assess the landscape characteristics of coffee agroforests in the Pangalengan Subdistrict and analyze how those characteristics influence the insect communities. Landscape metric approaches were examined to quantify landscape characteristics and the results analyzed using correspondence analysis to determine variation among samples, and simple linear regression testing was used to determine the influence of those landscape characteristics on the insect community. Seventeen sample locations varied in characteristics based on the proportion of the land cover classes, and landscape characteristics determined the number of insect species. The number of insect species showed strong negative correlation with landscape heterogeneity (R2=0.456) and number of patches (R2=0.514) and a weak positive response to the proportion of natural forest remaining (R2=0.150). Number of insect species showed a strong negative correlation to landscape heterogeneity, number of patches, and number of natural forest remaining simultaneously (R2=0.514).