Microplitis manilae Ashmead (Hymenoptera: Braconidae): Biology, Systematics, and Response to Climate Change through Ecological Niche Modelling

Abstract

The parasitoid wasp Microplitis manilae Ashmead (Braconidae: Microgastrinae) is an important natural enemy of caterpillars and of a range of noctuids, including pest species of armyworms (Spodoptera spp.). Here, the wasp is redescribed and, for the first time, illustrated based on the holotype. An updated list of all the Microplitis species attacking the noctuid Spodoptera spp. along with a discussion on host-parasitoid-food plant associations is offered. Based on information about the actual distribution of M. manilae and a set of bioclimatic variables, the maximum entropy (MaxEnt) niche model and the quantum geographic information system (QGIS) were explored to predict the potential distribution of this wasp in a global context. The worldwide geographical distribution of potential climatic suitability of M. manilae at present and in three different periods in the future was simulated. The relative percent contribution score of environmental factors and the Jackknife test were combined to identify dominant bioclimatic variables and their appropriate values influencing the potential distribution of M. manilae. The results showed that under current climate conditions, the prediction of the maximum entropy model highly matches the actual distribution, and that the obtained value of simulation accuracy was very high. Likewise, the distribution of M. manilae was mainly affected by five bioclimatic variables, listed in order of importance as follows: precipitation during the wettest month (BIO13), annual precipitation (BIO12), annual mean temperature (BIO1), temperature seasonality (BIO4), and mean temperature during the warmest quarter (BIO10). In a global context, the suitable habitat of M. manilae would be mainly in tropical and subtropical countries. Furthermore, under the four greenhouse gas concentration scenarios (representative concentration pathways: RCP2.6, RCP4.5, RCP6.0, and RCP8.5) in the future period of the 2070s, the areas with high, medium, and low suitability showed varying degrees of change from current conditions and are expected to expand in the future. This work provides theoretical backing for studies associated with the safeguarding of the environment and pest management.

Keywords: Microgastrinae; armyworms; biological control; climate change; environmental suitability; parasitoid wasp.

Figure 1

Microplitis manilae Ashmead, 1904, holotype female from the Philippines (USNM). (A) Habitus, lateral view; (B) wings; (C) head, mesosoma, and metasoma, dorsal view; (D) mesosoma and metasoma, lateral view; (E) hind leg; (F) holotype labels.

Figure 2

Microplitis manilae Ashmead, 1904, non-type female from Thailand (CUMZ). (A) Habitus, lateral view; (B) wings; (C–E) head; (C) frontal view; (D) lateral view; (E) dorsal view; (F) mesoscutum and mesoscutellum, dorsal view; (G) metanotum and propodeum, dorsal view; (H) T1–T2, dorsal view; (I) mesosoma, lateral view; (J) metasoma, lateral view; (K) wasp cocoon (left) and larvae of Spodoptera litura (F) (upper right).

Figure 3

Microplitis manilae Ashmead, 1904, non-type male from Thailand (CUMZ). (A,C) Habitus; (A) dorsal view; (C) lateral view; (B) wings; (D) head, dorsal view; (E) mesoscutum and mesoscutellum, dorsal view; (F) wasp cocoon; (G) mesoscutellum, metanotum, propodeum, and metasoma dorsal view.

Figure 4

Current geographical distribution of Microplitis manilae in a global context, displayed in yellow points.

Figure 5

MaxEnt outputs of Microplitis manilae under its current distribution. (A) Current suitable distribution in a global context; (B) importance of bioclimatic variables to M. manilae by Jackknife test; (C) ROC curve of potential distribution prediction; (D) curve of omission and predicted area. High-suitability areas have a probability of 1–0.77; medium-suitability areas have a probability of 0.77–0.46; low-suitability areas have a probability of 0.46–0.23; unsuitable areas have a probability of 0.23–0. AUC = area under the curve; MaxEnt = maximum entropy modelling; ROC = receiver operating characteristic curve.

Figure 6

Potential distribution of Microplitis manilae under the RCP2.6 climate change scenario in the 2070s. (A) Future suitable distribution under the RCP2.6 scenario in a global context; (B) importance of bioclimatic variables to M. manilae by Jackknife test; (C) ROC curve of potential distribution prediction; (D) curve of omission and predicted area. High-suitability areas has a probability of 1–0.75; medium-suitability areas have a probability of 0.75–0.5; low-suitability areas have a probability of 0.5–0.25; unsuitable areas have a probability of 0.25–0. ROC = receiver operating characteristic curve; RCP = representative concentration pathways.

Figure 7

Potential distribution of Microplitis manilae under three climate change scenarios in the period of 2070s. (A–C) Future suitable distribution in a global context under three scenarios: (A) RCP4.5; (B) RCP6.0; (C) RCP8.5. High-suitability areas have a probability of 1–0.75; medium-suitability areas have a probability of 0.75–0.5; low-suitability areas have a probability of 0.5–0.25; unsuitable areas have a probability of 0.25–0. RCP = representative concentration pathways.

Figure 8

Response curves between bioclimatic variables and predicted suitability. (A) Precipitation of the wettest month (BIO13); (B) annual precipitation (BIO12); (C) annual mean temperature (BIO1); (D) temperature seasonality (BIO4); (E) mean temperature during the warmest quarter (BIO10).