Latitudinal patterns in tachinid parasitoid diversity (Diptera: Tachinidae): a review of the evidence

Abstract

Insect parasitoids may be an exception to the typical biogeographic pattern of increasing species richness at lower latitudes exhibited by most taxa. Evidence for this ‘anomalous’ latitudinal gradient has been derived from observations of hymenopteran parasitoids and it has been argued that other parasitoid groups should show a similar pattern of diversity. Several mechanisms have been proposed to explain this disparity, most notably the nasty host and resource fragmentation hypotheses. We review and evaluate these hypotheses with respect to tachinid flies (Diptera: Tachinidae), and bring to the argument evidence from eight trapping surveys from temperate and tropical regions in the Americas including the United States, Costa Rica, and Ecuador. We find no evidence that tachinid fly diversity is lower in the tropics than in the temperate region. Our results, along with other lines of evidence, rather suggest that New World Tachinidae likely conform to the same negative relationship between latitude and richness as their largely phytophagous host taxa. We discuss geographic patterns of tachinid diversity in relation to ecological and evolutionary processes, and why they may differ from their hymenopteran parasitoid counterparts. Parasitoid taxa appear to vary strongly in their diversity responses to latitude and we concur with previous researchers that more survey data are necessary to reach strong conclusions about parasitoid latitudinal diversity patterns.

Biodiversity and Spatiotemporal Variation of Longhorn Beetles (Coleoptera: Cerambycidae) in Tropical Forest of Thailand

“…The results of this study revealed that a small proportion of actual species was found (15% or 199 species) of estimated (1275 species), suggesting that many of the 85% of longhorn beetle species in Thailand were not collected with support from the non-asymptotic species accumulation curve, based on Taxa S, as depicted in Figure 2 a. This tendency was similar in previous studies that reported 20–50% of the estimated number of longhorn species not being recorded [ 13 , 35 , 36 ], and other insect studies showed various percentages of undiscovered species; for example, 24–44% of ant species in the western Amazonian rainforest of Ecuador [ 37 ]; 10–20% of Auchenorrhyncha and Diptera in the tropical forests of Thailand [ 38 ]; and 18% of the Empidoidea community in Doi Inthanon National Park, Thailand [ 39 ]. Therefore, additional intensive survey with several combined sampling methods are necessary in order to evaluate Cerambycidae fauna in Thailand.…”

“…The results of this study indicated that the relationship between species richness and elevation was significantly negative with hump-shaped patterns and the number of species increasing by elevation at the initial phase; then peaking at the middle-elevation before decreasing at the high elevation. These characteristics are accepted as a general pattern [ 49 ] that is found in several examples of insect distribution, including that of plant species richness, which decreases with increasing elevation [ 36 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]. Middle elevations have many factors which make them suitable for insects such as optimal temperatures, greater host plant diversity or food availability.…”

High species richness of tachinid parasitoids (Diptera: Calyptratae) sampled with a Malaise trap in Baihua Mountain Reserve, Beijing, China

“…This study demonstrated the high sampling efficiency of Malaise traps. We recorded a relatively higher number of species in comparison to previous studies conducted in locations of similar latitudes over similar sampling periods 32 , 34 , 67 , 68 (Table 3 ). For example, Stireman 34 documented 79 species, and estimated a total of 122 species.…”

Predation and parasitism on herbivorous insects change in opposite directions in a latitudinal gradient crossing a boreal forest zone

“…An increase in diversity with an increase in latitude has been demonstrated for many groups of parasitoid wasps (reviewed by Burington et al, 2020). This direction of the latitudinal diversity gradient is opposite to the pattern observed in a majority of taxa (Willig et al, 2003) and indicates that parasitoids demonstrate very unusual responses to environmental variations.…”